_N.O.
lr.\.H
D.N.c.
18l ,
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>NO
-@-
(ILL.
HONEYWELL
FLAME
SAFEGUARD
PRIMARY
CONTROLS
The
Flame
safeguard
Primary
Control.
is the heart
of
the:
bu!'flll' control
~.
It
lrans/ales inputs 1rom the
flame delector,
controller, and limits into sequenced con-
trol

01
the
burner
molor,
ignilion, pilot,
and
main
fuel valve.
Primary
",ontrolfunclions
are summarized in Fig
1.
PRIMARY
CONTROL
FUNCTIONS
INPUTS
OUTPUTS
lIMIT~
CONTROLLER
"G
PRIMART
CONTROt
IGNmON
aUINER MOTOR \
PILOT VALVE
A
U
FLAME
~S~'G~N~'~'-1L
J~M~'~>N,,-,"~'~V~'I~SI,-+

FIG.
1-FUNCTIONS
OF
A PRIMARY CONTROL
The
complete Flame Sareguard Primary Control per-
forms
3
pdr :1pIJ
fI rlcttc:ni.
First, it sequences the
operation-start,
run,
and!hul·
down
-ot
the burner syslem. A
timer
may
be
added
10
the
primary
conlrollo
add
a
liming
Capability
10

the sequenc-
ing
function
o1lhe
device, and in this
case
the primary
con-
trol
is
known as a programmer.
8ec:oncl
the primary control supervises the presence
at
a flame,
cutting
off the
fU9J
Sl.Wly
if
flame
is
nol
present.
lNrd.
the pl'lmary conlrol checks
lise"
against l Im8fe
failure. Typically, the conlrol performs e -sa1e start"
check,

or
cheCks for a f1ame-simulaling failure before
startup.
II such a condition is present, the burner cannol
start. In ad:::lilion, most primaries also check the cootinUily
of
their safety switch circuitry. The ulllmate in self-check-
ing ability is the Honeywell Dynamic Salt Check syslem
which checks its internal circuitry about
1 to 4 Umes each
second during operation.
R7023
FLAME
DETECTOR
RELAY

The
simplest devJce in the
FS~
famityof
electronic con-
of
flame safegJ8rd syslems. It Is used most
COiTVT'lOl'1Jy
In
trol relays is the
R7023. This control is oot a primary con- flame safeQUard 8J:fjllcations -
trol.
It
does

nol
have any SEQJencing
or
programming
ability. Its relay
pulls
in
when flame is sensed, and dt(l:lS
out
on
loss
01
flame,
so
it
musl be used with other equip-
ment
It
a complete flame safegJ8td 8J:fjlicalion is
10
be
made.
The
R7023 is available In 2 mooels:
the
R7lJ238 and
the R7023C.
The
B mOdal
has

an
electronic circuIt for use
with rectification
type flame detectors. The C version
of
the
R7023 is for use
wilh
the ultraviolet "Mlnipeeper- detec-
tors-CT027A,
C703SA,
or
CT044A. TheSe small compacl
UV
tLbes offer
the
advantage
01
lower cosl sensing.
The
8
mcdel has dCllble pole-<:b.ble throw output switching ca-
pability; and
the
C version haS single JXlIe-<:b.ble
throw
output
switChing. Inlemal schematics
01
the 8

and
C med-
els are
shown
In Figs. 2 and
3-
It a control
does
not perform
aU
at
these functions,
il
is
not a complete primary control. An example
at
such a con-
Irol is the
R7023, to
be
covered next. The R7lJ23 only haS
the ability to supervise a flame. It
Ism
deSigned to
se-
quence
burner
operation,
fa
provj~

a safe start
cheCk,
or
to have safely switch capability.
Because the
R7023 is so basic In Its
daSl~,
It
can
be
used
as a basic building block in desl(J\!nQ various
I'y?9S
107
1.
as a replacemenl for R7lJ23 controls alreactJ in
service.
R70238
FLAME
DETECTOR
RELAY
lOAD
,.,.
"'-'"
flAM!:
,.,.
~y
::::
Jill
~

,.
LOAD_N.O.
LOAD_N,C.
'0'
COM
COMMON
u-+
'G
ILKTIONIC
OT)POWEI
U(TlFY
N(TWOU:
SUPPLY
HAMl
,,-+
100.
'

oto
0
(70
12A,(,
FIG.2
SIMPLIFIED SCHEMATIC DlAGRAM
OF
AN R7023B.
71-97558-1


,

.,'
2.
10
ack:I_
electron~
detection
capability
10
a bUrner
control
system.
The
R7023 can also
be
~
on
many non-1Iame safe-
guard applications where it Is necessary
to
provide a
switChing functIOn
as
a resull
01
a
SiQl1al
from a flame de-
tector. In such cases, the
flame
delec:tor doeS

nol
sense
R70ue
FLAME
DETECTOR
RELAY
~
,
(1)
•
flAME
0
nLAr
,
BLUI
IlIC110HI(
II
WHITE
Wf'WOII.
•
,
10AD-N.0.
LOAD·N.t.
tOMMON
'0
tl017A,
tl0UA,
u-+
IHOT)~OWU
O.

iU'~l1"
t1044A
,,-+
RAME
DmClOI
FIG.
3-
SIMPLIFIED SCHEMATIC DIAGRAM
OF
AN R7023C.
flame,
but
monitOl'"s some other pl"ocess
or
related func-
tion.
For
e)(8IT1'Ie,
an
R7023C could
be
usect
wllh
a
UV
de-
lector
and
a UV source to control a conveyor
bell

with a
prOCkJct
being
prOCkJced
running
along
the belt. A
UV
source
on
one sIde
of
the conveyor
and
a detector
on
the
other
side
of
the conveyor would
Jceep
the
relay de-ener-
gized as
long
as the products are present
on
the bell. It
lhe

products
were
missing, the
UV
deteclor
would
sense Ihe
UV
source
and
pullin
the flame relay, possibly
selling
off
an
alarm
or
shutllng
down
the conveyor
belt
and
prevent-
ing
any continued matfunctiOn In
lhe
process.
This
system
would

have the advantage ovar a normal pholosensilive
system
In
lhat it
would
no!
be
affected
by
arrtlienl
room
light
and
could
be
selectively sighted.
Some
other
possi-
ble applications are -
- automatic
Ii~t
control,
- automatic
OOor
~r
~nterrupting
UV
beam
trig-

gers
OOorl,
or
- counting Items
on
a conveyor
bell
(pull in
01
relay trig-
gers counler).
REMEMBER - The R7023
0:Jes
not
perform a safe slart
checking function suCh
as
is
found
in
other
flame safe-
guard
controls. The R7023 merely pulls in
or
drops
out
in response to
the
presenCE!

or
absenCE!
of
flame.
There is
no
buill-in protection against malfunction,
R485
PRIMARY
CONTROL

The
R48S
aci:is
10
the basic; alTplifier
and
relay of the
R7023 some SElQJ8nclng
ability
and
a safe start check.
The R485 is
tor
use
on
flame saf9QJ3.rd applications
where manual or semiautomatic control Is to
be
used.

~
manual system is one In
which
lhe
burner
is
purged,
start.ed,
iglited,
SElQJ8nced, modulated,
and
slopped
manually. A semiautomatic system Is one
in
which
lhe
burner Is started
and
.Ignited
~11y;
purged,
sa-
cpenCed,
and
modulated
automatIcally;
and
stopped
manually.
wllh

certain steps
and
conditions
SLP81Vised
by
safety Interlocks.) The S445A START-8TQP Station
or
other manual conlroller Is normally used with the R48S.
The R485
~
Incorporate a sefe stan check, which
will
no! allow the cor1trolto start
Ihe
burner
if
the flame de-
tec:tor senses a
118tTl8
al
startup.
This
can
be
d.Je
10
an
ac-
tual flame
j)(eset'l!

within
Ihe
combustion charrtler, a
f1BlT1Et"6imulallng
con'lxmanl
failure,
or
ant other condi-
tion simulating a flame. In any
of
lhese cases, the control
will
nol
peoni!
a
burner
slart.
A schemallc
of the R485B. Inclucing typical external
ccnneclions, Is
ShOwn
In FIg. 4.
Nole
that
the
R485 has 2
relays,
desl~led
1K
and

21<.
Relay 2K Is (he flame relay;
II Is activated thrlJl Vl
the
solid slale
elec:tronlc network
(flame
sig.al
8IT1'llfier)
when
lhe
flame detector senses a
flame. Relay
1t<
Is the
load
relay
in
this case. Other more
complex controls
may
have
relays perlotming addilional
59qJenclng functions.
Here Is the
S8CfJ8nCE!
01
q:l8ralion
of the R485B. When
the q:l8rator closes the master switch, terminal 1 Is

p0w-
ered. If the
name
relay contact
2K1ls
closed, lermlnal 8 Is
108
powered. (If a flame-simulaling failure is present, 2K
wlU
already
be
pulled in;
2Kl
will be
qJEln,
terminal 8 cannot
be
energized,
end
the
burner cannot
be
started.
This
is the
safe start Check.) The alarm (leoninal
3)
will also
be
ener-

gized
(Ihrou~
contact 1t(1) when the master switCh is
closed. It
may
be
desirable
to
add
a
¢St
alarm silencing
switch (as
shown
in
Fig.
4)
10
pr9Yenl
an
alarm
unW
the
system is started,
R4851
WITH
TYPICAL
EXTERNAL
COIIECTIOIS


_.
-
FIG.
4_
SIMPLIFIED SCHEMATIC DIAGRAM
OF
AN R485B.

When the operator pushes
and
holds in the START but-
ton
on
the
S4<lSA.
power
is
fed
from terminal 8 through the
START
switch to the 19l1llon. It also goes from terminal 8
(througr.
t~
internat Jumper
of
the S445A, the STOP
switch. the
high
limit.
and

the Jurrper from terminal 6 to
ler·
minal
4)
to the
burner
molor
and
pilot valve. The pilot
should
iglite.
Power is also
fed
to the 1K relay coil Oermi-
nal 6). Relay 1K pulls In. Contact 1
K1
opens, dEHnergiz-
lng
Ihealarm
(lermlnal3J. Contact 1K2 closes, bypassing
the safe start
contact
(2K1),
and
1
K3
closes.
When
lhe
pilot

Ignites
and
the flame Is detected. the
flame relay
2K
pulls in. Contact
2K2
closes, bypassing the
START
switch; the operatOl' can
now
release
lhe
START
bullon.
Contact 2K3 closes, energlzlrlQ terminal 7 through
contact 1
K3.
The
main valve(s) should open
and
the main
burner
shoUld ignite. The system Is
now
in the • run" con-
dition
with the
main
burner

tirirlQ.
If!he
fJame
goes out. the flame relay 2K
dropsout.
C0n-
tacts
2K2
and
2K3
open, d9-energizing terminals 5, 6,
4,
and
7.
The burner motor, pilot
valvoe,
and
main valve(s) are
de-enerQized. Relay 1K
drops
out
and
contact
1K1
closes.
energizing the alarm (terminal 3). The R485
does not
tecy-
cle
on

flame failure.
For normal shutCbwn, the q:>erator pushes the STOP
bulton
on
the S445A,
removing
power
from
tennlnals 6, 4,
and
7. Relay 1K, the
burner
molOt, the pllOI valve,
and
the
main vatve(s) are de-energlzed. The
burner
Is shut 00wn.
In
summary-lhe
R7023
conslsls
sifT1)ly
of
a flame de-
tection network
and
a relay. When
name
Is detected,

lhe
relay (SPDT
or
DPDT) pullS in.
When
flame
is
001
dBtecled
the relay drops
out.
The relay
has
00
buill·in safety fea-
tures. The R485
adds
a load
telay
to the
R7023-andwlth
It
lhe
ability to per10rm a
sale
start check
and
burnar
56"
(J./Elnclng on manual

or
semiautomaUc start systems.
The
following
sections
will cover, In detail, the appllca·
lion
and
operation
o1lhe
RA890, R4795
and
Rn95
pri-
mary controls.
The RA890
controls
use
the same baSic
hardware as the R485, but
add
severallnwrtant
features.
The R4795 also uses the same
basic
hardware, but
ac:k1!;
additional features
not
available

on
the
RA89O.
The RT795
improves on the R4795
and
is Honeywell's
most
cOl'Jl)l8te
and
\lersalile primary control.
RAS9D
PRIMARY
CONTROLS
The RA890
is
the largest volume flame safeguard de-
vice currently manufactured
by
Honeywell. Three different
medals, all solid state. are avaiJable-RA890F, G
and
H.
The RAB90F is
pictured
beJow.
The RA890F Is a solid state version
or
an older model
(RA890E). It

is
for
use with rectification type 'lame detec-
tors-llame
rods. rectifying photocells,
and
C7012A
or
C
Purple Peeper Ultraviolet Flame Detectors.
The RAB90G
Is
for
use with the C7027A, C7035A,
or
C7044A Minlpeeper Ultraviolet Flame Detectors.
The RAB90H
has
DynamiC Selt Check circuilry whiCh
provides a continuous check
for
possible
COl'f1X)l'l6l1t
fait·
ute.
It
directly
repla,c85 the RA890E
and
F

for
most appJi.
RU90F
'RIMARY
CONTROL
WITH
QUO
SUBBASE
0:270
SUB6Alif
•
F\.Ulf
s.o.Fn'l'
.j
I
LOAO
RU,.A'I'
Illtl
RllAY
(2KJ
DIlle,",
~~
ENC\.OUD
Run
IIIlII
~

:;
'/
.

Il'
FLAME CURRENT
TEST JACK
ARC
~A~
PRDTECTDR ___
C<J\I~R
SOliD
HATE
CIRCUITS
lllU~~RhO
FIG.
5-COMPONEHTS
OF THE RA890F.
cations,
and
mounts
on
the same Q270A
51
tbase
Recfifying flame rods are recc:mmended.
The operaling sequence
01
aU
the RA890's Includes a
pilot flame-eslablishing
peliod-a
period
of

time after
startup clrrlng which the pilot flame
must
be ignited
and
detected
or
salety shutdown will occur. If safety shu!c;t)wn
occutS, switch contacts in the RA890
open
and
shut oown
the burner. M
operator
mUSI
manually reset the switch
before the
burner
can restart.
This safety shutCbwn funcllon Is per10rmed
in
the
RA890 by a safety switch. which
is
a current-heated resls-
lance
wire wrapped around a bimetal. The switch is cali-
brated so that
if
it heals for a specific length

of
time, the
bimetal
warps
to
Cfl8r'1
a set
of
contacts. On each RA890
start. the safety switch begins
heating
altM
same time the
pilot
ard
19lilian are energized.
If
the
pilot
fails to
Iglile,
01'
is
not detected within the safety switch timing, the switch
locks
out
The safety switCh fimlrlQ Is, therefore. the same
as the pilot flarne-establishing
period
for

all RA890's.
OPERATION OF THE
RA890F
The followIng flQlJres
show
the q:>eratlon
of
the RA890F
Primary Control
under
both
normal
and
abnormal
c0n-
ditions. EtlergiZed circuits
are
shaded to aid the
explanation.
Fig. 6 shows the internal schematic
1m
the
RAB90F
in
the
stancbt
JX)Srtion
with the
disconnect
switch and all lim·

its Closed,
and
the controller q:>en. The RAB90F may
be
used
With
a low 01' a line vollage controller.
If
a line voIlage
controller
is
used, as indicated by the dashed line. termi·
nals T-T must
be
JUrJ1:lered.
Assuming
the use
01
a
low
voltage coolroller. the transformer
and
electronic network
are energized
(shaded circuit In Fig.
6).
If
a line voltage
controller were used, there would
be

no
power
at terminal
6,
and
the transformer and electronic
nelwork
wootd
not
be energized.
109
71-97558-1
•
•
The slard:Iy perlod is the only time during which the
0p-
eratIon using a line voltage controller differs trom the
op-
erallon using a
low
VOltage
controller. After the conlroller
clO68S,
the
'OPBrf:ltion
Is the same for either type. There-
fore,
both
controllers will
be

shown energized
on
the rest
of
the
figures.
Keep
in minc:lthat a Jumper replaces the low
voIlaga
c;ontroUer
If a line voltage controller Is used.
The
hook~
shown Is
tor
a.gas system.
The
operaling
seQ.JBl"lce
fo(the
RA890
wher;'used
on
oil is lhe
same,
bur
the
hookt.P
IS
r;hanged as shown In

Fig.
7.
The
R890F
contrails
pOwered only at terminal 6 (unlike
the
RA890E
or'
G,
which are pbwered
at
both
termInals 6
anc:f
11.
II
l6
not necessary to continually
power
the
solid
state electronic network
of
the
RA890F since lhere Is
no
hbe
W81r1"l1.4l
perkx:l required

on
start.
Nole
lhat
on
IImll
acllon,
or
~lng
of
the
tine vollage controller, all power
10
ttl:!
RA89d
ls
Intern.pted
118'OF 'AS
SYSTEM·
STAIDlY
.ow
~
VOLTMI~
_.
n~
,
~
,~



,
•
-
110
M~"""11
ALVll.
.~
•
1M""'''
MllT0
".,D
•
-,
,
•
L

l
•
u
nn
,g
,-
TO
fLAMl
PlTteTOIl
-
•••

•

FIG.
6-RA890F
IN
tHE
STANDBY
POSITION.
2NC·STAQE
Oil
VALVE
(1'
USEOI
1A8'O
HOOKUP
FOI
OIL
SYSTEIIS
IIIUflNEfI
MOTOR
_.,
IGNITION
151T-STAQf
OIL
VALVE
The wire pllot link
~
on
the schemalic Is used
10
adapt
the control for continuous pilot applications. Its

lJS8
will
be
covered In detail later. The test
~ck,
also In
lhe
flame
deleC1ion circuit, Is Included to provIde a means for
making direct measurement
of
the
flame signal currenl.
On
a call for heat the controller closes anc:llhe 1K relay
coil Is
pOWered
through a thermlslor, which delays
ilS
pull-
in
a few
seconds.
The
fulctlon
of
this delay Is
to
provide lime for the con·
trollo

delermlne whether the 2K relay Is pulled In (low volt·
age controller)
or
pulls
-In
on
start (when
lhe
Intemal
transformer and electronic
netwonc
are powered
by
the
clOSIng
of
lhe
contact
of
a line vOllage contrOller). It relay
2K Is pulled
In,
tnc:licatlng the presence
of
a flame (or a
cClll-
ditm
slmulallng a flame), contact 2K3 will
open
and

pre-
vent
pull-in
of
the
1K
relay. The
SlartL4J
cperatton cannot
continue
untillhe
flame goes out
or
unUithe ftame-slmulat-
ing
ccnjjtion
Is corrected.
The thermistor delay
of
lhe
load relay pull-in is normally
3 to 5 seconds,
but
II
may
be
somewhat longer
or
shorter In
the presence

of
extreme
afl'ijjenl
temPeratures. A few In-
stallations may
be encounlered where
Ihe
load relay must
pull
in
almost
Il'T\ITMKsialelY.
A spectal fast-thermistor model
of
the R.A890F with a delay
at
only 1 second is available for
lhese
installalions.
When lhe
1K
relay pulls in:
- 1K4 closes and shorts the thermistor out
of
the cIrculI.
- 1K3 closes to start healing the safety switch heater. It
also eslablishes a parallet circuil whIch will
hold
In
re-

lay 1K when
lhe
heater Is de-energized
by
the cpen·
Ing
of2K3.
- 1K1 closes to power lhe pilot valve
(gas),
or
burner
molor and firsl-stage oil valve, from terminal
3, and
the
i "ltlon
(through closed contact
2K1)
trom termi·
na14.
- 1
K2
closes with
no
Immediale effect unless a conlfnl.J'
ous pilot
is
U5ElCl
and the
pllollink
Is removed, In this

case, the pull·ln
of
1K powers the flame detection
circuit.
When the fleme delector senses the presence
of
the pi·
lot
(gas)
or
main (oil) flame, a small recti1ied currenl flows
SAFE
START
(HI(I(

= =-=:"


_-_

LhU:r;l~4-
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•
.A'"
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.ow

w.,.,
,


2U~
VOLTAGI

_.
a.1it-
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•
IGHITIOfII
t
<!>

n.
MIlITDIl
,
~,

OT
~

,

"
'"

U
,~
.Il>
~ACI<
"
~.I<

u~~~0
,.,";;(.!
~
TO
"LAMl
OlTKTOIl
•••
1'==
CDH"ICT
•
<,

'.~
.wITCH
"
"
TIMII
___
DI
DILAn

",u
If<
I

D~\
"
""5[0
POWIIl
.,,~

".
FIG.
7-
EXTERNAL CONNECTIONS FOR AN OIL
FIG.
8-
RA890F
OPERATION ON A
CALL
FOR
SYSTEM.
HEAT.
110
in the flame detection circuit. This small signal
Is
amplified
by the electronic network and acti

ates flame relay 2K.
When relay
2K
pulls In:
-
2t<1
cpens
10
cut off lermlnal 4, ll7'itlon.
-
21<2
closes to power lerminal 5, main gas


a/ve(s}
or
second stage
011
val

e as appliCable.
_ 2K3 opens
to
stop the healing O1lhe safety switch
heater.
,'The. syStem Is now
In
Ihe
-run"
condition and
Will
re-
main ir:'llhis condil.ion unlll the controller Is sallsfied, un-
less
lImi.1
j!ctlon, flame failure,
or
power failure causes Ihe
system to shut
dOwn.
If
the flame fails during •
run~

(or
it
for some other rea-
son a satisfactory signal Is not maintained in the flame
de-
tecllon circuit), the 2K relay drops out
10
CUi
ott the main

a1ve(s)
and relurn il7'itlon.
1A890F
CALL
FOR
HEAT-Ill
PULLS
.1
"~-:::."
t.n'.'


:=:.::.
'"
I@
In
II<3"~
,
M


,~
""

M

1111

OlTAGE
'"
CON_
TIIO~
(b~l~
,
'"
'""111-
•
-I
III
M"TOII

'.'
=.
•
a
TlU
'III
JIoCIi
L.i:1ii
2K
NOTeD

'Il.'f(~
~
uno
LINK
I~
~.
.•
-
"J;;
CO_.CT
-,.
"
"
'"
l

fnY
."'m:M
HU~
,.
on

"'lOT

D
llI_mON

IIO_.IU
~.
FIG.9

RA890,F OPERATION WHEN RELAY
1K
PULLS
IN.

I~
F
TO
flAM.
OI'TICTOII
•
1A890F
FLAME
DETECTED
-BURIER
RUIS
,,"
"'OlT"'GE
CON_
T"OulII
t,
TO ,

oor
OnlCToll
'''FnY
IWITCH
OI·INlllGWlO

n


"
•

l

co

011
"' 0
_.
IU"lT
IO.ITION
"
CI.rT
on
-
.=

-
C_ICY
I

ITC!'I
" "
,~
•
l'NK
"'~
r """


FIG,
10-
RA890F
OPERATION WHILE THE
MAIN
BURNER
IS
FIRING
("RUN"
PERIOD).
Systems like the RA890Fwhich relurn
Iglition
on
flame
failure are called ·re-Iight-
or
-Iglitlon
return- tallrolS.
Some codes require thai conlrols
which
retum
igIillon
do
50
wilhin
1 second after flame fallure, and modelS
ha

lng

less
lhan
1 second flame response time musl
be
u:sed
In
these installations. Contact 2K3
c/OSElS
lhe safety swilch
heater
circuit
It
the flame is
nol
f&eStablished in safety
switch liming (15
or
30 seconds), safety shulcbwn occurs,
The same figure lHustrates
what
t\aR:l9nS
II'
the burner
fails
to
light on start.
The
safely swilch hearer
tallinues
to

heal. with pllof and ignition energized, untll the safety
switch
~ar~
open.
PILOT/IGNITION SEQUENCE
Figure
12
shows onty the line

oltage porticn
of
the
RAB90F.
a.o.nT"l
Iwm:H
tol

n_o

"
__

CI.rT
OFF.
__
••
InI_
FIG.
11-
RA890F

OPERATION
IF
THE BURNER
FLAME
GOES OUT.
RA890F
L1IE
VOLTAGE
CIRCUIT
lIMIT{SI
,,-+
,.,
~
II
2:f!)
-
ti:;<9
4>
J2'
_

FIG,
12-
RA890F
TERMINALS
FOR PILOT/IGNIR
nON
SEQUENCE.
111
71-97558-1

An;
time relay 1K
pulls
ln,
terminal 3
wlJi
be
powered. If
1K
IS
In
and
2K
IS
out,
lermlnal 4
will
also
be
powered. Pull
In
of 2K cuts off
power
to
4 and powera 5.
So
far
we
have
~ldeted

only
the
~
where lQ1i-
lion
IS
ec:nleCted
10
terminal
4,
or
lnlem ded
looll1en,
In-
terrtpled
1Q1llion means thai
Ig'lltlon
IS
out
off
dJring
the
-run-
period. The
RA890F
may
also
be
I.lSEld
wllh Intermll-

lenl jgnjtjon,
or
with Ignition on wl:len the main
burner
is fir-
Ing {"run"·per,loc:lf simply
by"connecllng
the iQ1ltlon
transformer to larminal
3.
l'hiS
Is
more
common
on
direct
spark
igiled
oil burners.
The RA890F normally provides intermittent
pilot-
- a
pUot
which Is automatically Iir;tlted each
lime
there
Is a call for heat
and
which
burns

dJrlng
the
entrre pe-
riod that the main burner
is
firing (-run- period).
The
RA890may
.QQ1
be connected
for
inlerrupted plio!
(lSlless using exlema,!
circullry)-a
pilol
which is cut
off
sometime before the burner reaches Its -run- period.
It
may, however,
be
I.lSEld
with a conllnuous
pilot-a
pilot
which
burns
withoul tUrTll:Dwn IhrOlJl;1lOul the entire time
the
bumar

Is In service, whet.her the main burner is
Mng
or
noI.
CONTINUOUS
PilOT
SYSTEMS
The hookup for a conUnuous pilot
gas
system is the
same as shown in Fig. 6
excepl
thai the connections
10
ter-
minals
:3
and
4 are
not
made,
and
the RA890F
pilollink
is
Clipped out. Nole In the schematic that removing the pilot
link
puis
the delector In series with contacl 1
K2.

11'1
this
.
case,
the detection system
IS
lnterr~ed
when relay
'1
K is
out. When 1K
j.XJlls
In
on
a call
for
heat,
lhe
pilot will
be
de-
tecled,
if
il
is
prBS9l1t,
and
the main valve(s) can open. The
safe
slan

check
is
losl
on
conlinuous pilol systems.
A safe slart check can
be
acXied
10
I;OllUnuous pilot sys-
tams
by
using an additional relay. A standard switching re-
lay could
be
used to perfonT! this function
on
old
RA890E
Installation&. Because
of
laster
relay
Pun~ln
speed,
a spe-
cial hOOln.p uSing
an
R482F relay
wilM

thermistor delayed
pull-,ln musl
be
used
for
the RA890F. This
hookup
is
nol
teChnically a continuous
pllot
syslem, bul instead is a
melhod
of
providing plio! flame
dJring
the burner-offcyCle.
The pilot flame
i~
actually cut
off
and
then re-igniled
on
each burner start.
Pilolflame
Is Sl4'8rvised
ooring
the
off

cyele.
During the
off
cyCle,
!he
RA890F Is
powered
continu-
ously through contact 3K1; RA890 relay 1K
ispulled
in, the
pilot valve Is
~ered,
and
relay 2K is pUlled in
as
long as
the
pilot is proved. On e call
for
heal
by
the controller, the
thermistor in series
wllh
the R482F relay coil is powered.
This delays relay p Ill-ln Slightly.
Conlact
3K1
drops

out
long enough before
3K2
p IUS
In to
permitlhe
RA890F re-
lay 1K to
drop
out, stnJlling
off
the pilot. When 1K drq:lS
out,
Ihe 1K2 contacl opens In the flame delecllon circuit
and relay 2K also
drops
out.
The
RA890F is
now
in the
nor·
mal
SlardJy
IXlSllion (Fig. 6). When contact
31<2
In
lhe
R4B2F closes
10

repowar the RAB90F, the pilot is rS'lgnited
on
a normal start - atter
lhe
safe start check.
RA8iO CUTOFF SYSTEMS
In applicalions where
it
is undesirable
for
the RA890 to
relurn lQ1ilion
on
name
failure, an external
cutoff
circuit
must
be
used wllh the
~,F,
or
G. (The RAB90H in-
corporates cutoff.)
The
j.XJrp:lSe
of
the
cutoff
hookup

Is to
prevent
reCYCling
of the syslem on flame failure.
Whe.n
us-
ing
this hookup, flame failure wlll
be
followed
by safety
shUldoW'n, requiring
thattha
RAB90
be
manually resel ba-
10re
a restart can
be
made.
Culoff
systems
may
be
de-
SiQ1ed
SO
thai
igUlion
only,

or
iQ11tion and pilot valve, will
be
CUI
off
on
flame failure. One
hundred
percent
gas
shut-
off, Including pilot,
is
rEq.Jired for LP gas.
The cutoff system uses a switching relay with
~
ping
coolacts (contaclS
make
before
break) to transfer
control
of
the lQ1ition arxl pilot to terminal 5
of
the RA890.
Power to terminal
5, which controls the main valve(s), Is
Interrupled
direclly

by a dropout
of
the
flame
relay, 2K.
On a call
for
heal, terminal 3 is
powered
when
lhe
load
relay 1K pulls
in
and
,K1
closes.
The
burner
motor,
11
used, slarts.
The
pilot valve arxl Ignition ere
powered
via
lhe
following
circuit-control
twmiOftI 3 to relay terminal 5

10
relay lerminal 4 (thrt:VOt1lhe
normally
closed contacts)
to relay tenninal
6
~hrlXJ\tllhe
JU!l1'9rj
10
Ihe
pllol
valve
and
iQ11tlon.
When
lhe
flame
Is established, the flame relay 2K
pulls
in arxl 2K2 closes Control
lelTTlinal
5 is
powered
causing
the main valve
Is)
to open an:!
pulling
power
on

relay termi-
na18.
This
causes
the
R482D Relay
10
p IlI in (lermlnaI8,
10
7, to 1 through
lhe
jumpers).
When
the relay
pulls
In, relay
tEllrminal
3
is
po'N6l"ed from relay terminal 5
10
hold in
lhe
relay; relay lelTTlinal 6 is powered
from
relay terminal 8 to
power the pilot valve
and
ig"lilion.
lithe

burner
flame
g:l9S
out, relay contact 2K2 in the
RA890
wlU
open,
f8l"TlO'ling
power
from RAB90 terminal 5
and
from R482D terminals 8
arxl6.
The main valve(s)
and
pilot valve will close and Ihe ig"lition will
be
cut off.
As
the
'"

2F
,n
USIIIG
THE
THII·
~.
r1t,
~l:

RA890F
TO
MISlO(
b
MOIIITOR
PILOT
DURIIIG
THE
,
•
,
•
OFF
CYCLE
L
L1MITISI U (1<011-+
r'"
,J
f-
VOlU.GI
,.,lIN
CONUOUU
V,llVI15)

90F
• •
@
~
IGNI'ION
<D

'"
TO
FL,lMf
OUICIO.
~
., +
ON
CALL
FOI
HIAI
UI
OPllf1lrrOI,
.U
CLOUI

O

INIUIlT
0"""
Ilf1l1lUPItNG
POWtl
TO
II<I

n'll!
FIG.
13-
RABiOF
HOOKUP FOR CONTINUOUS
PilOT

WITH SAFE START CHECK
ON
CAll
FOR HEAT.
~
~ ~-

I
','
R482D contact between terminals 4
and
5 is
A)W
open. the
ignition
and
pilot valve cannol
be
energized again
unlillhe
R4a2D relay
drops
out. This can
occur
only atter the
RA890 load relay 1K
drops
out
upon safety shutdown. The
safety

switch
in the RAB90 will heal and safety shutoown
will
occur
In about 15
or
30
seconds ldePending
on
the
model).
The
RA890 must
be
manually resel to resume
operation.
OPERATION OF
TWE
RA890G
OperalLon
of
the RA890G is very similar
10
that
of
the
RAB9OF,
which
we
have covered in detail. The RA890G is

designed
10
be
used
with the C7027
A.
C7035A,
or
C7044A
Minipeeper Ultraviolet Flame Detectors only.
Note in the fallowing figure that the
RA890G
has
2
transfonners. The
low
voltage relay logic circuit is pow-
ered
by
TFI1
from lerminal 6, and the electronic
~Utler
nelwori(
is
powered
by
TR2
from
terminal
1.

(In
an earlier
IGIIITIOII
CUTOFF
STSTEM
R~nll
RU
y
Itarting .
'£;'IT';~:I~"

,
•
'"
'"
5
-!E.1"'~
(E.Z"'@'-
.!
RA890E,
(j)\.
~
"
C:O,,,nC:UD
_.'
TO
~'Olo
n,.

0.

DR
o. " "
.
M
IN
I-
V"'~V.!.I
~,=
F,G~
~
~
=
T

,

~
,
FIG.
14-
STARTING CiRCUIT FOR CUTOFF
SYSTEM.
IGIIITIOII
CUTOFF
SYSTEM
R"ZD
RELAy
,,~,
running
.~

I'~:"~':'
, .
~

•
",
'0'
•
(1_1"'.
E.2"''@'-
I

,
iF
RA890E,
~
~
FIG
\
2 '
~
""'=~
-
-~
_."
TI

I"

~

,
I.
CONNlc:TlO
"
"
TO
U
o.
T".
~"

n O~ o.
FIG.
15-RUNNING
CIRCUIT FOR CUTOFF
SYSTEM.
113
model, 1 Iransformer
powered
bolh
circuits from terminal
1.
However, a line voilage controller
could
not
be
used
be-
cause lhe load relay
1K

would
not
dtop
ouI
when power
was removed from lerminal 6, and safety shutdown would
occur when the conlrolLer
cpened.)
The safe start check
differs
from
thai
of
the RA890F in
that
It
Inc0rJXIrates safety shutdown. The electronic net-
work remains powered
as
long
as
the
disconnect switch
Is
closed. regardless
at
the type of controller usecl. A flame
Indication (causecl
by
an

actual
flame
or
by
a flame-slmu-
talJng condition)
during
the -ofT-
pericd
or
at startup will
pull
in relay 2K. Contact 2K3 will open. preventing load
re-
lay 1K from pulling in, and contact 2K4 will close. It a low
Voltage
coni
roller is used, the safety
switch
heater will be-
gin
heating
as
soon as
2K
pulls
In. " a line voltage control-
ler is
used.
heating

won',
start until there is a call for heat
and
the controller closes. safelY
shuloown
will
occur
about 15 seconds after heating starts.
During normal operation,
on
a call for
heal
the control-
ler closes and relay 1K pulls in.
When
1K pulls in -
-1K1
closes to
power
the
pilot
valve from terminal 3
and the ignition from terminal
4.
The
pilot ignites.
(On
an
oil system, the
burner

motor
and
first stage oil
valve are powered
from
terminal 3; see Fig. 7.)
-1K2
closes to
bypass
the thermistor.
-1K3
closes to establish a holding circuit
tor
relay
lK:
and
to establish a heating circuit tor the safety switch
haater through 2K3, 1K2,
and
1K3.
- 1
K4
opens to prevent
the
safety
switch
haater from
heating through 2K4
when
the

flame
relay
2K
pulls in.
When the
pilol
flame (or firSI-fitage oil flame) is de-
tected, the flame relay
2K
pullS in.
When
2K pulls
in
-
-
2K1
c:pens
to de-energi:ze terminal 4 and cut off the
ignition.
- 2K2 closes to energize the main valve(s) (or second-
stage oil valve} from
terminalS.
The main burner
lights.
-
21<3
opens; !he safety swilch heater stops healing.
RA890G
-STAIIDBY
POSITIOII


llU
HI

TI~
211
"'LAM.
IlnAYJ
Til'
TO
'LAMI
OETEcrD~
•
WHITI
Lf-~~_ l
~
,
FIG.
16-RA890G
IN THE
STANDBY
POSITION.
71·97558·1
I
','
- 2K4 closes with
no
effect. As previously described,
It
provides

a heating circuit
for
the safety switch healer
WrIng
lhe
safe stert check.
The sysIem
Is
now
In
the
~runft
condllionwlth
the main
burner firing. The
-run-
period
wilt continue unIi1lhe call
for
heal
is satisfied
0(
until the limlls open.
In either case, the load relay 1K will drop out. When 1K
drops
out
-
-
lK1
will open, cle-enQ(gizing the pllol valve or fjrsl-

slaga oil

alVQ
(IermTnal
3)
and the main valve(s)
0(
second-staoa oil valve (terminal 5). The
bumer
flame
will
go oul.
- 1K2 and
11<3
will open
and
1K4
will close, resetting
the rtA890G
fO(
the next cycle.
\'Vhen
the burner flame goes out, relay 2K will drop
out
The
2K
cOnla~ts
will
be
reset tor (he next cycle.

tr
a limit opei,s,'sa1aly shutdown wlll not occur.
\'Vhen
normal conditions are restored and the limil(s) closes, the
S)'Stem will restart and operete normally.
It
the flame goes out
wring
the
,-run-
period, relay 2K
will drop
out
When relay 2K
CSl'ops
out
-
2K1
closes to
power
terminal 4
and
ft
return Ignltion. -
(It -return Ig1llion" Is undesirable, the external cutoff
circuit shown
in
flg.
14 can
be

used.)
-
2K2
opens to de-energize the main valve(sj or sec-
ond-stage oil valve (lerminal 5).
- 2KJ closes to provide a
t16aUng
clrcult
tor
the safety
switch heater through 2K3. 1K2,
and
lK3.
-11
a flame
Is
not re-established
and
detected within
about 15 seconds. sa1ely shutdown will occur.
w If a flame
is
re-established, the operation will conlinue
normally.
IlltIe
wrner
'fails to
liglt,
operation
wlJl

be
similar
and
salely shutdown
will
also occur.
Uke
the
RA890f.
safely
shutdown requires manual reselling to restart (he system.
114
RA890H
SELF-CHECKING
PRIMARY
CONTROL
This control provides a higher level
of
safely than the
RA890F
or
G.
Dynamic Self Check circuitry providas a
continuous check
of
the RA890H for possible !lame-simu-
lating
component failure. Comp::nenl failure in
lhe
elec-

Ironic
network
causes safely shutdown, requiring manual
reselling
10
restart the system.
The
RA890H also i",corporales
~
eutaW
rather than
"fe-light"
("ignition
relurn")
It the flame goes out. If the
flame faits
during
the"
run" periOd. safely shutdown will
occur wnf'l
no
attempt 10
re-lighllhe
burner.
APPLICATIONS
The RA890H
is
designed for intermittent pilot appllca-
lions. It may
be

used
for continuous pllols only
if
an auto-
matic ialeclrlcally q:lEIrated) pilot valve is used,
ard
if
the
pilot
is
shut oown and re-igniledprior to burner start.
It
can-
nol
be
used tor interrupted pilot aw1icatlons without exter-
nal circuitry.
A flame rod
is
recommended
for
usa
with the RA890H;
a rectifying photocell
or
a C701ZA
or
C Purple Peeper UI·
traviolet Rame Detector may be used, but lhe system
dOes not provide a check

of
theSe delectors
dJring
the fir-
ing cycle.
The RA890H fealures
(1)
a tamper-resistant plastic
cover,
(2)
a green
signallighl,
(3)
a flame current lest jack,
(4)
a test button, and
(5)
three alann terminals.
(1)
The lamper-resistant plastic cover over the load and
flame relays
(1
K and
2K)
lessens the possibility
of
an
cp-
erator
@nlculatiog

them, which could result in an explo-
sion. The cover meets the General Services
Administration's requirer1"l'lnts
for
tamper-resistant
cOllers.
(2)
The green signal light blinks whenever the flame de-
leclor
senses a flame_ When the
burner
Is out, the liQht
Q!QWR
slightly to Indicate the control
Is
operatillQ In the
stanctJy
l'Tl(Xja ,,!itl'l the
power
00.
(3)
The flame current test jack lets an operator
comect
a W136A Test
Meter
(or equivalent microammeter) to
RA890H,
J,
IC
SELF·CHECICINC

PRIMARY
CONTROLS
VINYl
PROTECTIVE
BARRIER

"
FIG.
17-FEATURE$
OF
THE RAS90H.
measure Ihe flame signal current
while
the burner
is
firing
dJrlng
the
~run·
period.
(4)
The lest butron prOVides a slead')l reading
of
Ih&
rlame signal current When
an
cperalor
holds
il
in.

WUh
the
tesl button depressed, the green signal liQhI
dJes
not
blink.
(5}
The three alarm terminals are
for
connecting an
ex-
ternal alarm. They
accommodate
either a normally-qJen
or
a nonnally-closed alarm circuit. Contacts are isolated
from the rest
of
the Circuitry,
so
either a low voltage or a
line voltage alarm may
be
used. The alarm is energized
it
safety shutdown occurs.
COMPARISON OF
THE
RA890H
WITH

THE RAS90F
The external
hookup
and
the
Ignition
SEQJer1CEl
relay
contacts (1K1, 2K1. and 2K2) are the same as
for
the
RA890F. Other similarities are;
- a flame siQnal amplifier in the electronic
networ1<,
-a
test
jaCk
for measuring the
flame
signal current,
- a safely switch (SSj In the
load
relay
(1
K)
circuit,
i!nd
- a thermistor to delay the pull-in
of
the load relay

11K}
dJring the safe start check.
The big difference from the RA890F is the sel1-check-
ing circuit in the electronic network. Relay
31<
pullS
in
and
31<1
closes to complete the
flame
deJection circuit when
power is
a~lied
to the electronic netwOrk. When ftame is
detected, cheCkillQ
action
begins.
Contacl3K1
opens
and
Closes
and
the green signal light
blinks
atxltJt 3 times a
second as
101lQ
as flame is detected. Checking action
Slops.if

the
flame
coes
oul
or
if
there is a CO!l'fXYlBnt failure
in
the
networ1<.
Relay
41<
pulls in
and
Slays
in
whenever cheCking ac·
tion
takes place. The flame relay
(21<)
pulls in
(thrCll Q1
1K4
and
41(4)
when 4K pulls
In,
and
holds
itself In

thrCll Q12K6.
Flame failure
or
network componant failure will
cause
41<
(and thuS load retay 1K) fo
drop
out
(4K2
~J.
Conlacl
1K1
operlS
to
d&energite
all fuel valves.
and
the
safety
swilch heater starts heating.
safety
shutdown occurs
in
about 15
seconds.
'O

" "
=:.I"~"

RA890H-POWER
OFF
FIG.
19-AAS90H
SCHEMATIC
OIAGAAII
WITH
THE
POWER OFF.
115 71-97558-1
Other differences from the RA890F are
in
the low volt-
age relay logic circuit. More
COl'Tl'lax
switChing requires
aci:ilional
1K
and 2K contacts
(11<2,
21<4,
2K5, and 2K6)
and new
relay.
4-K_
contacts (4K1-4K4).
The 'Iollowing
fi~res
Show the operation
of

the
RA890H Se,,-ehecking Primary Control under bOth nor·
mal and abnormal conditIons. Energized circulls are
shaded
to
aid
the eKPJanalion. The external hookup
shown
Is
for a gas.system. For an
oil
system, lhefirst-stage
011
valve and burner motor replace the pilot valve on lermi-
nal
3,
and the seCond-stage
011
valve
Of
used) replaces the
main valve(sj on'termlnal 5.
(See Fig. 7).
RA890H
NORMAL
OPERATION
Normal operation can
be
divided into 4
modas-(1)

stancbi,
(2)
call 'lor heat,
(3)
the A run
A
period,
and
(4)
satis-
facllon o11heGalifor heat.
(1)
Standby
Mode
(Fig.
19)
Fig.
19
shows the internal schematic for the RA890H in
the
stancbi
mode with the master switch closed and the
low voltage conlroller
~
t1
all limits are closed,
lhe
power s~1y energizes the transformer,
and
the elec-

tronic network turns on. Relay contacts
3K1
close to com-
plete the flame detecllon circuli.
(lte
line voltage controller
were
used, as indicated by the
dashed
line, terminals T·T
would
be
jurrpared. There would
be
00
power
al
terminal
6,
and
(he trans'lormer and electronic network would not
be
energized. Relay conlacls
3K
1 would stay open.)
Thestancbyperiod is the only lime ciJring which theop-
eraUon using a line voltage controller differs from the
op-

.OLV''''

.~
I-
.,

TE~
~ _

,

on
,


.1

Ye'.

_moo
RA890H·STAIIDBY
MODE
I,f.

,'
FIG.
19-RA890H
IN
THE
STANDBY
MODE.
eratlon using a low

vo1taQ9
controller. After the conlroller
closeS,
the
operation
Is
the same 'lor either Iype. There-
fore. both controllefs wlll
be
shown energized on the resl
of
the
f1~res.
Keep
In
mind thaI a Jumper replaces the low
voltage conlroller
t1
a
line
voltage conlroller is used.
(2)
Cell
for
Heel
(Fig.
20)
On a call
10r
heal. lhe controller closes. The trans·

former secondary energizes the load relay 1K IhrouQh Ihe
sa1ety
swilch heater
(SS
HEATER), 2K3,
lhe
thermistor,
4K1, lhe low vollage conlroller (or T-T Jumper),
and
the
safely switch contacts
(SS). The continuity
01
the safety
swilch heater is proven. The lhermistor delays the pull·in
01
1K
(aoout4 seconds nominal)
to
letlhe
conlrol check 'lor
a flame
Of
a circuit failure simulating a flame. The delay
timemaybeasshort
as two seconds at 125
F,
or as long as
30 seconds at minus 20
F.

As the thermistor warms up. the
1K relay may!'!Y!TI slightly be'lore it pulls in. This is normal
and
not relay
·qhatler.~
When relay
1K
pulls In, relay
conlacls
1K1, 1K2. 1K3.
and 1K4 close. Closing
01
1K1
energizes Ihe pllot valve
and
iglition
(terminals 3 and 4), and the
pilollgniles.
Clos·
ing
011K2
bypasses
4K1
and the (hermislor. When 1K3
closes, lhe transformer secondary begins heating the
safely switch heater through 2K3, 1K2, 1K3, and 2K5.
With 1
K4
closed, relay 2K can
pullin

when 4K4 closes
(4K
pulls in when flame is detected).
RA890H·CALL
FOR
HEAT
r-~-'-I'
~
'-
'~==~.
~_.; ,
,.,
>IU

,.
,
VOLV'''''
'"

~~'
'"
i
~~
,
~

.,
,\
-
[

n,
•
',,,:.

,.
~
,. ",
'"
• •
"'
'"
,.
-
""i

~;o0
,
-
'"
'""
•
""
,
0

CO-{]
~.=r-:,
•
~
.

"CO<
._'~~
_.
"

+
-"
"

.~,
•
FIG.
20-RA890H
ON
A
CALL
FOR HEAT.
116
(3)
The
"Run"
Period
(Fig.
21)
When the flame
detacta
senses the picot flame, relay
3K il'lJl:le_electronlc network begins its checkll'lQ action. It
pulls
In

and
drops
out aoout 3 limes a
second
as
long
as
the detector senses a
flame.
The
green
slgnallighl
blinks
at
thiS
same
rate. Relay 4K
pulls
In
ard
stays In
as
long
as
3K keeps checkIng.
When
4K
pulls
in. relay con/acts 4K1
and

4K3
open,
and
conlacts 4K2
and
4K4 close. ClosII'lQ
of
4K2 holds in rela'll 1K through 1K4,
41<:2,
the low voltage
controlfer (or T·T'jllri'1per),
ard
the
SS
contacts.
When
4K4
closes;'the
flame retay
2K
pulls
in through 1K4, 4K4, the
low
voltage conlloUar
(of
T-T
~,
and
the
55

contacts.
When
the flame relay 2K
pulls
in, relay contacts 2K1,
2K3,
and
2K5
~n,
and
contacts
2K2.
2K4,
and
2K6
Close.
Opening
of
2K1 de-energizes the ignition (terminal
4).
CloSIng
of
21<:2
energlzeslhe
rna!n
valvefs) Ilermlnal5),
and
the maIn burner ignites.
When
2K3

and
2K5 open, the
safety
switch
healer
slops heating. The transformer sec-
ondary
holds
in relay
2K
through 2K6, the row voltage con-
troller (or T·T
jurrwr),
and
the SS contacts. The system
is
now
In
the &run"
period
with
lhe
main burner firing.
(4)
Satlsfactlon
of
the
Call
for
Heet

The
RA890Hwill
re(um\o
the standJy mode (Fig. 19) in
the
following manner.
When
the
burner supplies enough
heat, Ihe controller
~ns.
For
a low 'iQltage controller, the
1K and 2K
rela~
drop
out,
but
the transformer
and
elec·
tronic
network
stay
energiud.
(For a line voltage
conlrd-
lar, the transformer
and
electronic network are

de-energized,
and
all relays
drop
oul.)
Relay
2K
drops out firSI; contacis 2K1. 2K3,
and
21<5
';-"
close,
and
contacts 2K2. 2K4,
and
2K6~.
Wilen relay
1K drops out, contacts 1K1,
11<:2.
1K3.
and
1K4 open.
Opening
of
2K2
de-energizes the main valve{s) (Ierminal
5). Opening ot
1K1
de-energi'ZBS
the

pilol valve
and
igni·
tlon
(terminals 3.and 4).
All
automatic fuel valves close and
the
bJrner
flame
goes
out.
As the flame deleclor
no
longer
senses a flame, relay 3K stops
its CheCking action and
re-
lay 4K
drops
OUI.
Oonlacts 4K1
ard
4K3
clos&,
and
con-
RA89OH-IUN
PERIOO
•

-
•••
_,,,r

ole:.!"

0 "
.,
_."
I'''''''

-,-
-
-
'"
~'::

,
~

o.
0
"""-"
FIG.
21-
RA890H
DURING
THE
"RUN"
PERIOD.

tacts 4K2
and
4K4 open.
As
the electronic netwotk stays
on, contact
3Kl
Sla~
closed.
All
relay contacts are
I'lO'W
in
the stanclJy
position.
RAll90H
SAFETY
OPERATION
Safety operation can
be
divided
inlo
5
Cordtions-(1)
safe slart check,
C2l
no
trams eslablished,
(3)
flame

goes
out
durll'lQ the
-run-
period,
(4)
component failure In the
electronic network, and
(5)
IImil
acllon
c:I
I]DT'I8I\tary
power failure.
Safety shurrJown occul"$.tor conditions 2.
3,
and
4 at:out
15
seconds
a1'ter
the safety swItch
heater
iSS
HEATER)
beI,;Ins
heating.
The
safety
swllch

contacts
(SS)
~,
drq:lping
out
the load relay 1K
and
the
name
relay
2K
(If
they are
stHl
p.llled-in)_ All relays will
be
In the
Nncb)'
p0-
sition.
The
burnef cannot
be
started
again
untillhe
saf9ty
SWilCh
on the RA890H
Is

r8SEl1
rTlBnuallry.
(1)
Safe
Start
Check
(Fig.
23)
11
a flame
pr
a condition simulating a
name)
is present
at start up, relay 3K starts its cheCking action
and
relay 4K
pulls
in. Relay contact
4JO
opens.
preventing!he
load
r~
lay 1K
from
PJlIing in. The thermistor
dela~
the pull-In
01

1K long enough 10r
4K1
to
open.
The
lK
relay contacts·
cannot close,
so
lhe
start up
operation
cannot
contnue
untillhe
flame g:J8S
out
or
unlll
the llame-simulating condi-
tion Is corrected.
(2)
No
Fleme
Established
(Fig.
24)
The
load relay
TK

has
already
pulled
in on a call
fOr
heat
(1K1,
11<:2,
1K3,
and
1K4 are closeo'). The pilot
valve
and
ignition (terminals 3 and
4)
are
energiZed. The pilot 00es
nd
ignite, so the
flame
detector senses no ft9ma. Relay 3K
ct:es
not
start checking,
so
relay
4K
cannot
pull
in. Contacl

4K4
CbeS
not
clOse, so the rlame relay
2K
carn:J( p.Jt in.
RAa90N
1I0RMAL
OPERATIOII
CAll
FOA
"'lAT
•
lO

O
Rnn
II
""US
,~.
•
'G~IT'O!'l
""0
"'lOT
vAcVI
ARI
E~UO'UO.
•
UHT'
$lO',rC:H

"I

TfAal

'IUHU"

FLAME
PROVED
III UN
PERIODI
• fcAOOl
~n",v
IK
""US'"
•
'''''''''000
'5
Ot·UltRGIIIO
•

,

VElSII.
(NERGIIEO.
• SAFETV SJlITCH
.,t"'TER
nT)OS HEAlI'll),
CAll
FOR
HIAT

SATlSflEO
& RElAYS
ORO.
Our
&
,un

elVES
CLOU.
•
R"_"
RHUR"'5
TOST.NO,
•
oa(
FIG.
22-SUMMARY
OF RA8S0H
NORMAL
OPERATION".
117
71-97558-1
,
','
Contact 2K2 cannot close, 60
the
main
valve(s! (termInal
5)
cannot open.

lh8
safety
swnch
heat conllrues
to
heat
thr~
210,
11<2,
1K3, and 2K5. safety
shl.Jtc:Dwn
will
oc·
cur In abcul 15 seconds. When !he SS contacts cpen,
re
lay 1K
wHl
drop
out.
Opening at
1K1
will dlHlnerglze the
pllot valve and 1IJllllon nermlnals 3 and
4).
(3)
Flame
Gou
Out
During
the

"Run"
Period
(Fig.
25)'
'
The flame detector
stops
sensing a flame, so relay
3K
~
cheCking·
~
relay
4K
cW~
out
(4K1
and 4K3
close;
41<2
ana'
4K4 opsn). When
41<2
c:pens, relay 1K
drq:.soul(lK1,
11<2,
lK3.
and
lK4
open).

Openlng011Kl
dlHlnerglzas the
pilot
valve and main valve(s) nermlnals 3
and
5)~
lh8
/glillon
(Iermlnal
4)
is
alreactj Cl&-energized
&lnce relay 2K
stays pulled-in
thrCllJltl
2K6,
and
2K1
is
~
when
'4'K3
closes. the safety swllch heater begins
healing thrCll Qi 2K4, 4K3,
and 2K6.
safety
shutdown will
occur In
abcut
15

&eC0'1ds.
IA890H.1l0
FLAME
ESTABLISHED
'''''0 " "_

I""'"
•.
"

Y"
"
_

FIG.
23-RA890H
SAFE
START
CHECK
RA890H.SAFE
STAIT
CHECK
r-

~
,ou. '•
1:··1-
r
•:::


:=,~
,.,
>c,
,

n.

".m""
"'0'
"'v,
,

.,
'"~~
'"
IC·
IIC
.,
•
~i
,
,

,


'.
'"
1m
.

~
lID
f(i)
.,
•
•
"

"'"~
::0
0
-,
,.
'.
.,
O'
'110
'"
"".,
".


,-,
I
'>
"'''<"
•
,

,.

"

Ill
-':J
_"
_.
4
"
,
•
FIG.
24-RA890H
IF
NO
FLAME
IS
ESTABLISHED.
".
(4)
Component
Failure
In
the
Electronic
Net-
work
AI Stan!.&)
If
the
COl'T(Xln8I'lt

failure haS occurred since the last
cy
cle and Is
pras«lt
at
start
~,
the
RA890H will cperate the
same
as
If
no
name
15
establiShed
(see
Fig. 24, condition
2).
Relay 4K cannot
pull
n,
150
the flame relay 2K cannot
pull in. Contact
21<2
will not close,
SO
the main valve{s) can-
not

c:pen.
lh8
safety switch
healer
will continue
10
heat;
safety shuldown will occur In
abcul
15
seconds.
Durina
the
-Run-
Period
It the cOIlW"l9'1I failure occurs during
the
-run-
pe-
riod, the RA890H will c:perate the same as It the flame
goes oul (see Fig. 25, condition 3). Relay
4K
drq:m out,
de-
energiZing relay 1K Opening at 1
K1
dB-energlzes the
pilot
valve and main
V81ve(sj.

The safety switch heater will be-
gin heating; safety shuldown wilt
occur
in about
15
sec""""
(5)
Umlt
Action,
or
Momentery
Power
Failure
(Fig.
26)
If
a Ilmll
opens
because
01
an
abnormal condition,
II
qJens lhe power line (L
1)
from the master switch
10
termi-
nal 6. A momentary
JX)Wer

failure
would
likewise remove
power from terminal
6.
Loss
of
power
dlHi08rgizes
the
transformer and eleclronic
netWOrk.
Relay 2K drq:m
OUI
very quiCkly (2K1, 2K3, and 2K5 close; 2K2, 2K4,
and
2K6
cpen). Opening a12K2
Cl&-energizes
the
main valve(s) (ter-
minal
5),
and
the
bumer
flame goes
out
Relay 1K drq:.s
wi

nexl
(1K1;'lK2,
1K3~
and1K4
ppen). Openil"'Q
of
1K1
d&energizes the pilol valve and Ignilion (terminals 3 and
4).
and
the pilot flame goes oul.
With
contacts 1K2 and
lK3
cpen, the safety switch heater cannot heat,
150
safety
shuldownwill
not
OCCur.
Relay 4K drq:m out last, in about 2
seconds
(4K1
and
4K3 close; 4K2
and
4K4 cpen). Since
the electronic network
is
de-energi:Z:ed, contact

3K1
is
open. When normal conditions are restorea, the Iimit(s)
closes and'or
JX)Wer
Is restored
10
terminal
6.
lh8
burner
will restart
and c:perate normally.
NOTE: The use
of
manual reset limits is desirable to pre-
vern the system from cycling
~!'
the limits, and
10
en-
RA890H.FLAME
CiOES
OUT
DUIIIlCi
r.~~i~

lUll
PEIIOD
FlG.

25-RA890H
IF
THE
FLAME
GOES OUT
DURING THE
"RUN"
PERIOD.
sure thaI the conditlon which causes the limit action is
detecled as soon as possible.
RA890H
,"OR CONTINUOUS PILOTS
If an RA890H Is useclfor a continuouspilol, the Ignillon
and
pliO! valve must
be
automatIc (electrically operated).
If
a manual ignilion
or
plio! valve is used, the
S'yS!em
wl/l
nOl
restart after limll action
9r
power
inter~tion.
HOOKUI:'
WrrnOUT

SAFE STAAT CHECK
ON
CALL
FOR HEAT
The s'iri-tplest hook4J'IS
shOwn
In
Fig. 28. The only dif-
ference from lhe normal hookup for an intennil1ent pilol
is
in
the location of the controller.
The
controller is connected
in series with the main valve(s),
so
power
Is
applied con-
tinuously
to
terminal 6 through
the
limits. A line voltage
controner Is used,
so
T-T Is
~red.
RA890N·L1MIT
ACTION,

OR
MOMENTARY
POWER
FAILURE
~

~

~~"~~.
.~;.
~~~,.,.
f-
••
~':::~"
~'~~
;"
••••
n

'
,.
;
"" :;,.:~

m
,.

~
,


:::
,.,'
H~-~-9
~
rPlln~Y.(t,
==~.,
S'
-;; ".1
-0
••
"
~
~
I-
''''··iO
r" t'-':l~'~
,
:;';'~
0
"'
j
t;
'-t<';> ,%r
'"
o.,,~
r.\1""""""",
'I
:;.
~
~:'c=::::r"-·

ei
"

,
.~
0
"."
RA890H
SAFETY
OPERATION
I.UE
START
CHiclC.
•
'L"'''''I
IDP n
III.U1.4

C'OI
""UIf<T
AT STARTVI'.
•
PRlvl

un
RT

NO
HAME
ESTABLISHED

•
~~UY
SHull''''''".
Jl'LAME
GOES
OUT
DURING
"RU""
PERIOO
•
LO"'''
UC"'V
'K
OflllKOIJ'
•

,

V""VIIS!
0000
p,,,')T
ulvl

AE
[)U"r

o<EO.
•
_"'ElY
So+UTOOO'I"

COMPONENT
FAILURE
IN
ELECTRONIC
NETWORK

T n
",.T",
O

V"

l
ou.,,,,,
"AUN"
P~AlOO

!TY
lil'lUTlIOfI".
LIMIT
ACTION,
OR
MOMfNTARY
POWfR
FAILURE
• AESTAATS.
FIG.
27
SUM
MARY

OF RA890H SAFETY
OPERATION.

IMPORTANT
THIS HOOKUP DOES
NOT
PROVIDE A SAFE
START CHECK EVERY TIME THERE IS
A
CALL
FOR HEAT.
Normal Operation
The
load relay
1K
pUlis
In
when the master switch
15
closed.
ClOSing
of
1K1
energizes the pilot valve
Oerminal
3).
and
lhe
pilolls
ignited.

(In
the normal hookup for
an
in-
termiUent pilol, 1K cannot pUll in
and
the pilot cannot
be
Ignited
unlilthere
Is
a call for heal.)
When
lhe
flame is delected, 3K begins
lis
checking ac·
tion and 4K pulls in.
The
flame relay 2K
pUliS
in when 4K4
closes. Contact
2Kl
qJeIls, de-energizlng the ignition
Oer-
minal
4).
If
lhe

pilOI goes oul, safety shuldown occurs.
On a call for heat, the controller closes. Since
1Kl
and
2K2
are already closed, the main valve(s) (tenninal
5)
~
energiZed, and
lhe
main burner
is
lit.
When the call
fD.r
heat
Is
satisfied, the controller
c:p:Ins,
de-enerQizing lhe main
valve(sJ
Oerminal
5).
The main
valve(s) closes
and the main
burner
Q::l8S
out,
bul

the
pilot
remains
Hl.
Safety Ooeration
A safe start
cheCk
is provided
QC&
when the master
switch is closed inilially, or when power
is
restored after
safety shutoown, limit aclion,
or
power failure-OQ! when-
ever there
Is
a call for heal.
111here
is a flame (or a flame-
simulating
condition) present when lhe master swilch
Is
closed, 3K will start lis checking aClion
and
4K will
pullin.
The
opening o14K1

and
thermlslor dolay will prevenlload
relay 1K from
pulling in,
just as In the normal operallon for
an
lntermittenl pilot.
However,
once
lK
pUlis
In,
it will stay
in
until lhe masler switch
Is
~ned
or
until safety shut-
down occurs.
1he
controller cannot
inler~tlK,
so
there
will
be
no
more safe SIan ctIecks.
IA890H

FOR
CONTINUOUS
PILOT
NO
SAFE
START
CHECK ON CALL
FOR
HEAT
"'
/
' '-
".

"~
-
.

FiG.
28-RA89DH
HOOKUP FOR CONTINUOUS
PILOT - WITHOUT
SAFE
START
CHECK
ON
CALL FOR HEAT,
119
71·97558-1
The

rest
of the safety Operation
Is
the same
as
for inter-
millenl
pilot q:orBllon.
FUP-FLOP
-tIRCUIT
WITH SAFE STAAT
CHECK-
.,
RAl90HFOR

'
II,
r'"
~"
,
CONTINUOUS
PILOT
I~
"f,
.
,~
WITH
SAfE
START
CHECK

-oN
CAll
FOR
HUT
, ,
.
{::J-
E""-
,
."
~

"
•

.
.

:'
,

-
"
!\tj~
iii'>
~
.
-0
-'


::::
,

=
::.0

-
~
L1:D
~~= jJ
I
, ':.~

,~
.
-::
" "
I

-
=~
1"1"
FIG. 29 RA890H HOOKUP FOR CONTINUOUS
PILOT-WITH
AN
EXTERNAL
FLIP-FLOP
RELAY
CIRCUIT
TO

PROVIDE A SAFE
START
CHECK
ON
CALL
FOR
HEAT.
To
provide a safe
st;:t.rt
check Yiheoevar there
Is
a call
for heat, the flip-flop
refay circuit shown in Fig. 29 can
be
usee!.
A line voltage controller is again used,
so
T-T is jum-
pared.
The
R48ZF Relay
is
between the conlroller and ler-
rninaI
6.
The
3K3 relay coolacls are between terminalS
and

the main valve(s). The
pilaf
Is
not
strlCl1y
a coolinuous
piiOl
as
It
is lurned off
and
re-Igniled
on
a call for heat.
The R482F Relay controls the application
of
power to
terminal 6
of
the
RABOOH.
During. the stanct:ly mode,
p::IWEIr
is
applied to lerminal 6 through the IImil(sl and
c~
tacl3K1 of the R482F Relay. During the
"run"
pariod,
3K

of
the R48ZF Relay is pulled-in; power is applied to lermi-
nal 6 tht~ the limil(s), controller, and 3K2 contacts
of
lhe R482F. On a call
for
heal, power to
larminal6
is inter-'
fl4)Ied-the
thermistor
in
the
R4B2F
d9tays pull in 3K
so
thai
3K1
~
before
31<2
closes.
NQrmal
Operation
The load
relay'
K pulls in when the masler switCh is
closed. Closing
of
1Kl

energizes Ihe pilot valve (terminal
31,
and the pilot
IS
117'11ed.
When lhe flame
IS
detected, 3K in the
RAB90H
begins
lis
checking action and
4K
pulls in.
The
Ilame relay 2K
pulls In when
4K4
closes. Contact
2Kl
opens, dlHInergiz-
lng the
117'ItiOf1
(terminal
4).
If
the pilol
QC)QSout,
safety
shut.

down occurs.
So
far, the operatiOllls exacffy the sameas
for
the previous
hookup
shown in Fig. 26.
120
On a call for heal,
the
conlroller closes. Retay 3K In lhe
R482F
pullS
in
through
lhe
thermistor. Conlact
3K1
in the
R482F
operis, removing power from terminal 6
of
lhe
RAB90H. All relays In the RA890H
drop
oul,
and
the
pilot
goes out. After a short delay

(c:lle
to the thermistor), con-
lact 3K2 In
the R482F closes, reapplying
power
to tl:\rmlnal
6
of
the RA890H. Contact 3K4 In
lhe
R4B2F closes, by-
passing
the thermistor. Contact 3K3 In the R482F closes,
connecting Ihe main
val e(s)
to lerminal 5
of
the RA890H.
From lhis
lXlint, the stan
\ P
and the
"run"
paried are
the
same
as
for the normal cperalion
of
an RA890H with

an
Intermillenl pilol.
The
safe start check takes place first.
If
there
is
a flame (or a condition simulating a flame) pre-·
sent
dJrlng
start
\ P,
relay 3K In
the
RA890H starts
Us
checking action and
4K
pufls in.
Contact4Kl
cpens,
so
the
load relay 1K
camot
pull In (delayed
by
the thermistor)
and
the system cannol

be
started. Thus a safe slart check is
provided every time there Is a
cal~
for
heat
by
momentarily
interr\ pting power
10
the RAB90H
Ihrough
the R482F
Re-
lay. The pilOt
Is
turned
off
while
the
check
Is
made, and
therl re-ignilecL
If
no
flame (nor flame-simulating conditlon)
Is
delected,
the

load relay 1K pulls In. Closing
of
1
K1
energizes the pi-
lot
valve (terminal 3),
and
lhepilot
Is
ignited. When the pilot
flame is delected, the
flame relay 2K
pulls
in. Closing
Of
21<2
energIzes the main
valv&(s)
(terminal 5). The main
valve(s) opens
and
Ihe main burner is Ii!.
When lhe call for
heal
is satisfied, the controller opens.
Relay
3K
in
the

R482F drops out. Contact 3K3 in lhe
R482F opens, de-eoergizin;l the
main
valve(s) (te[minal
5). The main valve(sj closes, and the main burner
goes
oul. Contact 3K2
in
the R462F opens, removing power
from terminal 6 of the
RA89OH.
All relays in the RA890H
drcp
oul.
Opening
01
1
K1
de-energizes the pilot valve (lerminal
3).
and the pilO!
goes
oul. Contact
3K4
in the R482F
opens,
removing the bypass from Ihe thermistor. When
3K1
in
the R482F closes, power is reapplied to terminal 6

of
the RA890H. The load relay
1K
purls in,
1K1
closes, the
pilot valve opens,
and
the piiOI
is
ignited. When the flame
isdetected,lhe
flame relay 2K pulls In,
2K1
opens,
and
the
ignition turns off.
The
conllnuous
pilot
has
been re-
established.
_
Safety
Operation
A safe start
cheCk
Is

prOVided every
llme
there
Is
a
Call
for heal.
The
R482F relay
lnterr~ts
power
to
the RA890H.
All relay contacts
in
the RA890H return
to
the stanct>y
po-
siUon, and
thepllol
goes out. After a short delay, power is
reapplied
10
the RA890H. If a flame (or a
fla~lmulating
COndition)
is detecled, relay
3K
In

the
RAB90H starts its
checking action and
4K
pulls in. Cor;tact
4K1
opens, pre-
venting the load relay
lK
from pulling in (delayed
by
the
thermistor).
The syslem
carY"lOf
be
started.
The
rest
011he
safety operation
JS
the same as for inler·
mittent pilot operation.
SUMMARY
OF
RA890
PRIMARY
CONTROLS
OP'ERATION

A
safe start
check
Is
nol
applicable
to
the RA890E
or
F
operating with a continuous pilot. On
the
rest
of
the med-
als,
11
a flame (or a cOndition
simulallng
a flame)
Is
present
at
start up, the load relay
lK
cannot
pull
In.
The
start up

operation cannot continue
until
the
'lame
goes
oul
or
until
the tlame-slmulallng
ceroillon
is corrected.
safety
shut-
down
will
occur
for
lhe
RA890G
only.
On limit
actlon
or
momentary
oower
failure, all models
recycle. They restart wnen
normal
conditions are
restora:::l

and
all manual resel
limils
are
reset, If necessary.
SAFETY
SHUTDOWN
If the safety
swllch
healer
is altowa:::llo heat
for
a sufIl-
clent perioo (15
or
30 secondS,
depending
on
the modal),
the safety switch contacts will open
and
the load relay
1K
will
drop
out, Terminals 3,4,
and
5 (pilot valve, ignition,
and
main valve) will

be
de-energizecL AlI1ue1 valves will close.
The system cannol
be
restarted until the safety
SWilch
is
reset
manually.
The
operator
must
wait
at least 1 minute
for
the heater
10
cool before
pushing
in the safety switch
reset
bullon
in the cover.
safety
shutoown
occurs
if:
- a flame
(or
a flame-simulating condition) is presenl at

start up,
for
the RA890G only.
-
no
flame is established,
tor
all mcdels.
-the
flame Is
not
re-establishad after
il
goes out
and
the ignition is energized
again
to try to relight the
burner
(called
~rellg.t~
or
"ignition
relurn"),
for the
RA890E,F,
or
G.
- the
flame

goes
out
during
Itle
~run-
perloo
ard
no
atlelTp( is
made
to
r&-light
(-eutort"),
for
lhe
RA890H.
TABLE
II-COMPARISON
OF
R890
OPERATION.
Jrf'f'UCA,TIOHS:
RAnOE
RAnOf
RAnoa

~"
INl'EAl'\lJFI"ED
Of\
INTER-

• •
•
•
MTTENT
IGNITION
lliTER~rrroo
Pl.OT
• •
•
•

0'"
a.P
oWTOM,AT
COfol71HUOUS
PLOT
'"""'"
,


0'
"""'"



'"
"""''''"'
SAFESTAATCHECl<
• • •
•

RE'CYa.ES
ON
UMrT
ACTlON
Of\
~Ot.IENT
Mff
• •
• •
POWER
FALURE
SAFETY
S/'IUTOOWN
IF,
Fl.AME
IS
INOlCATEO
AT
•
'"''''

NO
FLAME
IS
ESTMUSHEO
• •
• •
I'\ IlJ"lE
IS
NOT

!'lE·
Im.o.auSl'l£DAf'TER
•
• •
-AE1 IJ.'«"
FLAME
GOES
OUT
-curOFF-
•
COMPONENT
Ell.S
lH
THE
AA8llO
NETWOFll(
•
COMPARISON
·OF
RA890
OPERATION
TABLE
I-COMPARISON
OF
RA890 FEATIJRES
COMPARISON
OF
RAB90 FEATURES
Solid
slale

circuijry
eliminates annual vacuum
lube
re-
placement.
Since
there is
no
tube
10
warm
up
before start-
inlOj,
application
at
power to the RA890
is
no! required
dUring
the.
slancby
period. Olher
advanlalOjes
are
In-
creased" resistance to vibration, longer life,
and
grealer
reliability. .

'.
~t1eckina
circuitry,provides a continuous check
of
the RA890H for IXlSSible component failure. Component
failure in the electronic network causes safety shutdown.
The
type
01
flame sIgnal amplifier in
lhe
RA890 is Incll·
cated
In
Table
r.
RECT indicates an amplifier for use with
reetificatlol1 type flame cIeleclors. These include reclifying
flame
rods, rectifying photocells,
and
C7012A or C Purple
peeper Ultraviolet
Flame
Detectors. A flame rocl is recom-
mended for
use
with
the
RA890H.

The
Uv
amplifier,
in
the
RA890G only, is for use with the C7027A, C7035A,
or
C7044A Minipeeper Ultraviolet Flame Detectors.
The
arc
gao
proteclor
protects the RA890 network
against damage frOm high vollage ignition inlel!erence.
It
conducts
at
high
voltage levels
10
bypass the network. In·
terference at these levels
is
greal enough
to
mask the
flame signal, thus
causing
a shuloown
01lhe

syStem-:
The
arc
gap
will glow
i1
interference is severe. thus providing a
visual
Indicallon
01
Ignition interference.
The
plastic
cover over the load
and
flame relays
(1
K
and
2K) meets General
services
Administration's require-
ments
for
!anl)er·resistanl
covers. II lessens
lhe
possibil-
ity
of

an
operator
manipulating the load
and
flame relays,
which
could
result
In
an explosion.
The
areen
flame signal
light
blinks
When
the flame de-
tector
-sees"
the flame, indicating that the self-cheCklng
circuitry is
wor1<ing
property.
APPUCATlONS
All
mcdels
can
be
used
10

provide either Intern pted
or
intermittent ignition,
and
Intermittent pilot. A continuous
pilot
can be
used
with-an:
- RA890E,
11
you
remove the jumper screw.
- RA890F,
it
you
~
the
pilol
link jumper wire.
- RA890H
jf
you
use
an automatic (electrically
operated)
pilot
valve
and
one

of
the
special
hookups
for a
continuous
pilol
(Figs. 28
and
29).
RAIIOE
RAUOI'" RAuoa
Fl

GH
SOUD
STArr;:
CIRCUITRY
•
•
•
SEl.F-CHEa<JNG
CIFlCUlTRY
•
R.A/olE
SIGNAL.
AMPLIFIER
AECT
'''''
W

""
IlAC
aN'
PROTECTOR
• •
F'l ASTIC
COVEfl aVER RElAYS
•
GAEEN FL.WE
SIGNAL
UClKT
•
12'
71-97558-1
- a
COl'J"4XlOOl1t
fails
In
the
electronic nel'NOrk
of
the
RAll9OH.
UPDAnNG·RA800 INSTALLATIONS
Updallng
an
RA890
installation
with
an RA890H results

In
the
ao:1itionalfealures listed In Fig.
30.
If's
easy
10
ra-
place an
RA890B.C,E.
or
F.
No
changes are required In
the
wiring
to
lhe
sut:O&se;
simply
remove
the
old
conlrol
and
mount
the
new
one. If a cutoff circuit was
used

In
Ihe
old
installatioo.
it
is
nol
necessary
to
remove
the external
cutoff relay. However,
the
RA890H
iflcorporates
·cutoff,·
so the suttlaSEI
may
be
rewired
10
~!imlnale
the
unneces-
sary external cutoff ralai', If.desired.
If
the
hot
line (L
1)

is
CO'1(}Ar,!ed
10
lelminal
1
in
fhe old Installation, It
maybe
lett
connected, even
though
it
Is
not
required
to
operate
Ihe
RA890H.

~

•
_.
u"
=~t"';"

:.0
"


~

r ,
' : ~
•
.;:'.=:::0'
1._ _

F
' " ;i:'"
-r-'
'-jfl'1
.~.
=

~:
;

_,

~I
•.
~
,,'
""
_

FIG.
30-
UPDATING RA890

INSTALLATIONS
WITH THE AA890H.
R4795
PRIMARY
CONTROLS
ThElse
controls U&e
much
of
the
proven, reliable hard-
W31saroci1cullryo1
the
RA890's.
In
addition,
thevP£O'Iida
a pre-purge capability
before
Ignition, and Include lerml-
na.ls
for
proving
airflow. Inlerchangeable, color·cOOed,
pll lQ-ln
amplifiers permit any R4795 10
be
used
with
e:ther

rectification
or
ultraviolet type
flame
detectors. However.
R479S's
~
prOYipe-the setf-Checking feature included
in
the
RA890H.
The R4795A
provides·
recycle.
~
If the name
goes
out
'during
lhe
"run-
period,
the
A4795A
w)l)
recycle
oncs
Ihrough pre-purge and try
to
establish

the
pilot. If
the
pilot
flame is
nol
re-establlshed. safety
shutdown
will
occur.
The
A4795D fnCDrporafes
"cutoff~'
rather than "recy-
cle.·
lithe
flame goes
out
during
Ihe
"run"
period. safety
shutdown will
occur
with
no
allempt
to
re-light the pilot.
All A4795A is

shown
in
Fig. 31.
The
R4795D looks
lhe
same except
lhal
n
has
an
ao:1ltional cutoff relay
(41<)
in
lhe
lower right cornet in 1ronl
of
Ihe
Iransformer.
APPLICATIONS
The R4795A
and
0 Frame
safeguard
Primary Controls
provide
solid Slate, electronic,
flame
safeguard protection
for commercial

and
Industrial gas or
011
burners. They are
designed
for
intermillent
pilot
appllcallons.
lhey
Cannot
be
used for interrupted
pilot
applications
without
external
circuitry.
The R4795A meets
Underwriters
laboratories
Inc.
ra-
QJirements 10r
011
burners
with
firing
rates
of

20
gallonsper
hOur
or
less.
or
gas
burners

lth
firing
rates
over
400,000
Stuh
up
to
2.5
million
Bluh;
If a 30, 60.
or
90
second pre-
purge limer
is
used.
The
R4795D Is designed
for

use
on
power
burners (di-
rect·
or
indirecl·fired),
makeup
air heaters,
and
space
heaters.
It
meets Factory Mutual and
Factory
Insurance
Assoclalion IF.I.A.) requirements
lor
mak.eup air heaters.

FIG.
31
-COMPONENTS
OF
THE
R4795A.
122
FIG,
32-SCHEMATlC
DIAGRAM OF THE

R4795A
OR
D WI'Tli THE POWER OFF.
QPERATION
The
cperation
01
the R4795A is similar to that
of
the
RAB90F except
for
the actlitional pre-purge function. 0p-
eration
of
the R4795D is the same as that
of
the R4795A
except that
11
provides
"cutaW
instead
of
~
recycle"
if
the
flame goes out durirlQ the
~run"

period.
Fig. 32
shows!he
schematic diagram tor the R4795A
or
D
wilh
the master switch
cpen
and
the
power
off. Because
at
ils
complexity, the internal, low voltage, relay
IOQlc
cir-
cuitry is
nol
shown. The plug-In purge
limer
Is
part
of
the
low vollage circuitry. The R479SD differs
trom
the R4795A
FEATURES

In actlilion to
RA890
features, the R4795A and D in-
clude
(1)
plUQ-in
purge timers,
(2)
circuitry for proving air-
flow,
and
13)
plu~jn
flame signal arrpUfiers. The plug-in
components
are
easy
10
replace,
resulting
in
faster
service
and
reduced inventory.
(1)
The
solidsTa!.e','·pfug-ln
purge IImers
can

be
ordered
with timings 017,
10,30.60,
or
90
seconds,
thus providing
flexiblilly in meeting pre-purge requirements.
(2)
Terminals
are
provlded
for
conneclion
01
an
airflow
switch
ts.
prove airflow before the pre-purge period starts,
dUrlng purge,
and
during the Sr'\lIre
"run"
period.
(3)
A choice
at
Interchangeable, color-coded, solid

slale, plug-In, flame signal amplifiers permits arrt R4795
to
be
USed with rectification or ultraviolet type flame detec-
tors.
The
R7.289A
Rectification Amplifier, wilh a green
backplate, is
tor use with rectifying flame
rcx1s,
rectifying
photocells. or C7012A,C Purple Peeper Ultraviolel Flame
Deteclors. It also contains an arc gap protector
similar to
the one in the RA890F and
H.
The
R7290A Ultraviole!
Amplifier,
witha
purple backplate, is for use with C7027A,
C7035A, or C7044A Minipeeper Ultraviolet Flame
Detectors.
Other features, also included in the RA890's, are
solid
state circuitry, optional lerminals for an external alarm,
and a
Ilame
currenllest

jack (on the plug-in amplifiers).
R4195A
SAFETY OPERATION
Sa'ety"CflSrallon can
be
divided Into 6 conditlons-(1)
safe start check,
(2)
purge timer failure,
(3)
air1tow
failure,
(4)
00
flame eslabliShed.
(51
flame goes
out
c1Jrlng
the
~run"
period,
and
(6)
limit
acllon
()( momentary power
failure.
Safety shutdown occurs
for

condillons 4 and 5 !after 1
atlerrpl
10
re-Il""t) about 15
seconds
after the
aa1Bty
switch healer begins heating. The safety switch cartacts
only in an actlitional cutoff relay (4K), whIch is also In·
cluded in the low voltage
cIrcuitry.
Terminals
a,
7,
and
6 on the
0270
Slbbase
Oabeled
In
yellow) are used
'or
the R4795. These are the
same
termi-
nals
laDelBd 6, T, and T
(In
while) used tor (he RA890's.
The

external
hCX;Ikup
shown is
'or
a gas system. For
an
oil
system, the
first·stage oil valve
and
burner motor replace
the pilol valve on terminal 3,
and
the
SEtCor'd-5tage
oil
valve (i'
used)
replaces the main valve(s)
on
terminal 5.
(see
Fig. 7).
The
R4795 uses terminals
3,
4,
and
5exa.ctly the same
as the RA890's. However,

power
Is
awlled
to
terminal 1
inslead
01
terminal a
(6
on the RA89Q's). Terminal a
Is
used for the burner motor (fan or blower) to provide the
pre-purge
function.
An
airflow swilCh
Is
connected be-
tween lerminals 6 and 7
(T
and T on the RA890's). There-
fore, a low voltage controller canoot
be
used
with
the
R4795.
The ignition sequence relay contacts are nurrbered dif-
ferently than for the
RAB90's-1K4,

2K2,
and
21<3
Instead
at
1K1, 2K1,
arrl2K2
respeclively. Otherwise. these
con-
(acts perform the same funcllons. Also there is an ackli·
tional 3K2 contacl between the
hal
line
(L
1)
ard
the other
contacts.
NORMAL OPERATION (R4795A OR
D)
During
lhe
stancby
period
with the master switch
closed,
00
power
Is
applied to the R4795 since the lil'\8

vottage controller
Is open.
On a call for heat,
lhe
controller closes.
If
aJllimils are
closed, the transformer secondary energizes the low volt·
age. relay
~
CirCUitry.
Relay 3K will PJIl in through the
safety switch heater. proving ils continuity. Contact 3K2
closes, energizing the
bumer
motor (terminal 8).
When airflow is proven
and
the airflow switch closes,
the flame signal
amplifier
Is
energiZed
and
lhe
PJrge timer
starts. At
the end or the pre-purge, relay
lK
PJIIs

In.
C0n-
tact 1
K4
clO68S,
energizing the
pllol
valve
and
ignificn
(Ier-
minals 3 and
4),
and the
pilol
ignites. The saf9ty switch
heater
will
begin healing,
Wh8'I the flame deteclor senses the pilot ftame, the
Rame
relay
2K
pulls in. Opening
of
2K2 de-energizes the
1001110n
~ermlnal
4). Closing
of

2K3 energizes the main
fuel valve(s)
~ermlnal
5),
and
the main burner iglites. The
safety
switch heater
stCflS
heating,
and
the PJrgB llmer
Is
resel. The system
Is
now
In the a run"
periodwllh
themain
burner firing.
When the
bumer
SlWlles
etlCJUI;tl
heat, the controller
opens. All relays
drop
out and the R4795 relurns to the
slanchy position.


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71-97558-1
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(SS)
q:lEIn,
removIng all power
from
lhe
low vollaQ8. relay
logic circuitry. All relays
drop

oul
en::!
the contacts return to
the stanci:r)' poslUon (same as In
Ag.
32). The burner can-
not
be
sta!te9
~ga.ln
unlilihe
satety switch
on
the R4195ls
reset manually.
(1)
Safe
Start
Check
If a, flame (or a flame-slmulating
cc:nc:litlon)
Is present
wring
the pre-purQ8 period.: relay 2K pulls In. Internal re-
lay
SWIlChil')g
will
r9ffiO\le
fX)Wer
from

the purge timer. The
tlmerwllJ
step,
so
thai the toad relay 1K cannot pull In. C0n-
tact 1K4
eat'IDOl.
close,
so
the pllOI cannot
be
1~lled.
The
burner
motor
wlU
call1rue
to run, providing a call1nuous
purge (sate
rallur~.
The start
up
q:lEIration cannot con-
tirue
unt1llhe flame
g:l9S
out
or
I.I'ltillhe flame simulating
CO'ldItlon is correcled.

(2)
Purge'Tlmer
Failure
Iflhe
pluiln
purQ8 llmer Is noI properly Installed,
or
Is
nol
MClionlng
prq:lElrly. pre-purge cannot be completed,
so
the load relay
1K
cannol puJlln_ Contacl 1K4 cannol
close,
so
the
pilot
cannol
be
i~lted.
The burner motorwill
conIirue
10
run, providing a continuous purQ8 (sate
fallure).
(3)
Airflow
Failure

If airflow Is not
prOV9I1,
the airflow switch w!tl nol close
a :j
pre-purge cannot
be
started.
If
airflow falls
wring
pre-
purge, the
airflow switch will open,
the
timer will stop, and
pre-pu~
camoI
be
completed.
11
aIrflow fails
wring
the
-rt.rI-
period,
Iheairflow
swllch will open and all relays6X-
cept
3K
will

drop
out. Ga'llaot
tK4
will
~,d&energiLlng
lhe plio! valve, Ignition, and main valve(s) nerminals 3, 4,
and
5).
Terminal 8 (burner molar) will remain powered. If
airflow is rlHlSlablished, the airflow switch will close,
lhe
purge timer will start,
ard
the stan
~
opsration will begin
again
with pre-purge.
(4)
No
Flame
Established
Relay 1K
has
alraaety pulled In,
so
the
sa1ety
switch is
healing; contact 1K4 Is closed,

so
the pllot valve and
I~i.
tion (terminals 3
en::!
4)
are energized. The pilotlXlElS nol
""'lie,
so the flame
deleclor
senses
no
flame. The flame
relay 2K cannoI:
pullin.
Ga'ltaol 2K3 will nol close,
so
the
main
valve(s) (Iermlnal 5) cannol
be
energized. The satety
switch
will
conlirue
to heat LrllU safety Shutdown occurs
On
abOUt
15
S&CO~.

(5)
Flame
Goe.
Out
During
the
"Run"
Period
When the flame detector steps sensIng a flame, Inter-
nal
SWitching causes
both
the flame
rela~
2K
en::!lhe load
relay
1K
to
drop
out
Conlact1K4
opens
to
dEHlnergizeter-
mlnal&
3.
4,
ard
5.

Tna
pilot valY8 and main valve(s) will
close. It the airflow is stlll proven,
lhe
purge
timer
will start
and pre-purge will begin. After pre-purge, 1 aUerrpt will
be
made
to re-lighl the burner. Relay
1K
will pull in,
lhesatety
switch heafer will begin·healing, and conlact 1
K4
wilt
close. The
pilot valve (terminal
3)
ard
Ignition nenninal
4)
will
be
energiZed.
If
the pilot flame Is
not
re-established,

safety shutdown will occur.
(6)
Umlt
Action
or
Momentary
Power
Failure
If a limit opens because
of
an
abnormal condition, it
q:lEIns the power line
(L
1)
from the master switch to lermi·
nal 1. A
momentary
fX)WEll'
1allure
would
likewise remove
power from terminal
1.
Loss
of
power
da-energizas the
transformer.
All relays

drq)
out
ard
the
contacts return
10
Ihe
stan:;I)y position (same as In Fig. 32).
AU
automatic fuel
valves close
ard
the burner
molar
stops running.
When
normal conditions are restored, the limil(s) closes and/or
fX)Wer
is restored to tenninal
1.
The system will restart and
operale normally.
NOTE: The use
of
manual reset limits is desirable
to
pre-
vent the syslem from cyCling
off
lhe

limits,
and
10
en-
sure that the condition which causes
the
Iimil action is
datecled as soon as possible.
R4795D SAFETY
OPERAnON
Safety q:lEIralion for the R4795D is
the
same as for the
R4795A except for lhe
following conditions.
In the
sate start check, Ifa flame (or a flame simulating
Condition) Is
pr6S9f1t
wrlng'lhe
pra-purge period. internal
relay 4K
(the·
cutoff- relay) will also pUll In, causing the
purge
limer
10
stq)
and the safety switch healer to begin
heating. Safety shuldown will occur In

aboul
15
seconds.
11
the flame goes out d.Jring
lhe
-run-
period, internal
switching
causes • cutoff. - The R4795D will
not
recycle
throug.
pre-purge. No allllllTf.ll will
be
made to
re-Iighlthe
burner before safety
shutOOwn
occurs.
R7795
PRIMARY
CONTROLS
The
Rn95
Is Honeywell's most complete primary con-
troL All models have Integral flame arrpllfiers nhe R7795A
and C are for ultravlolel
delecllon
systems, the

Rn95B
and 0 are for recllflcation delecUon systems),
and
two
field-selectable fealures allow unlq.Je Inslallallon
YElrsatll-
Ity. The Installercan
selecl100r
4 second trial for
pj~~
lloii
and recycle
(l(
lockOut
operation
on
flame failure.
Solid stale
pl1.Q'In ST795A Purge TImers used with
lhe
R7795 providepre-purge timings
of
1.5,
7,10.30,60,
ar90
seconds. A safe.start feature prevents
start~
wllh
lockout
If a ftarne

or
a flame &tmulallng failure exists.
Olher fealures
of
the
R7795 Include terminals for
con-
necllng a line voltage airflow switch
10
prove airflow from
124
the
start
of
the pre-purQ8
throug.
the
run period. meter
jack for
measuring the flame
SI\Tl81
while the syslem is in
q:lEIration, a powered alann
t8lTT\lnal
to
q:lEIrale
an
exter-
nailine
vollaQ8 alann

or
safety lockoul, anda manual reset
safety switch.
The
Rn95
Is sl"cwn
in
FltlJre 33.
APPLICATIONS
The
Rn95
Flame SafeQ.J8rd Primary Ga'ltrols provide
f1ameou1
protecllon plus automatic control
of
commercial
and
lnc:1Jstrlal
gas
and otl burners. The R7795A
ard
Bare
cla:slgned for Intennltlent pllot applications. The
Rn95C
EI436
Q7!J5A
WIRING
SUBBASE
__
/ST79SA

PREPURGE
TIMER
COVER
FIG.
33-Rn95
SYSTEM
COMPONENTS.
and
D
are
designed
for
interruptedpilot with delayed main
valve applications., A tun-test
switch
is provided
on
the
R7795C
8Jld D

All models meet Underwriters Laboratories. Canadian
Sfandards
Associalion.
and
Faclory
Mutual rEQJirements.
OPERATION
The
operating

sec:J,Jences
for
.R1795
mocIels
are de-
scribed
below,
and
illustrated in the Hming diagrams (Figs.
34
and
36). Inlernal schematics
at
intermiUent models
(R7795A
and
B)
and
inler~ed
pifol mOdels (A7795C
and
D)
are
shown
in
Figs.
35
and
37.
R7795A

AND
B
The
Rn95A
and
B provide the following cperational
sequence
when
used
with
tt'e apprq:lrlate flame
deteclor
(A1795A requirQS an ultraviolet deteclor. R1795B r9QJires
a rectification type deleClor). Refer
to
Figs.
34
and
35.
The
RT795 Primary Control is ready
to
start
up
when
the
burner
c:onlroller closas (limits
are
Closed).

With
p;:lwer applied (limits
and
c:or,lroffer closedand
no
flame
sigial
present) the
3K
relay pullS in and the
burner
roofor (terminal 8)
is
enerQi:zed. '
As
soon
as
the
airflow
switch
closes (tennlnals
:3
to
8)
and
with /he RUNfTEST
switch
In the RUN posilioo, the
125
ST795A Pre-pJrga

Timer
starts
to
time out (pre-purga
begins).
NOTE:
The
ST7S5A Pre-p Jfge
Timer
ralums
10
zero
any
time
the
alr1low switch opens
or
the
RUN/TEST switch
Is
moved
to
the
TEST
posilfon.
The
pre-purge rilStans
when
the
airflow switch recloses

or
lhe·
RUNffEST
switch
is
relurned
to
the
RUN position.
AI the
end
c1
pre-purge (ST795A
limed
out) the
1K
and
4K
relays
pull
in, simultaneousi)' enBrg-:zing
the
igllUc.n
transformer (terminal
18)
and
the
Interllfllecl
pilot valve
(terminal 5). This statts rile 10

or
4 seccndpilOI flame
es-
tablishing period. Safety shutctJwn
and
loCkout
will
occur
it presence
at
name is not proven
within:
10 secondS
11
the
ORANGE
tumper
IS
NOT
CII~.
4 seeonds
it
fhe
ORANGE
jun'plr
IS
Clipped.
If the
RUNfTESr
switCh is movecl

to
the
TEST
poslllon
wring
thepilo!: flame astabli5hing period, the sequence
Is
slq:Jped in trial
for
pilot flame. The safety swItch healer
Is
enerQzed
durlnq
fhis
pilot
flame establishingperiod Mlerl-
ever flame is notpresent.
safety
shutdown
ard
lockout will
oct;ur
il
lhe
absant:e
0'
flame
exc~
15
seconds

(nominal).
MAIN FLAME
IGNmON
TRIAL
At
the
ard
c1lhe
pilot
flame
establishing period (10
or
4
seconds),
wilh
pilot. ffame present,
ard
the
RUNJTEST
71-97558-1
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FIG.
34-0PERATING
SeQUENCE FOR THE
R7795A
AND B WITH INTERMITTENT PILOT.

switch
In
,he
AUNPOSliion,
lhe
Ignition iranstormer
!laml-
nal
18)
is de-energized and the main valve (terminal
6)
is
energized staning
Ihe
maIn Ilame Ignition trial. Ten sec·
onds into fhe main flame Ignition tria)
Ihspilof
"alva
~9Imi'
nal
5)
is
d&-energlled
and
the delayed rnaln valve
Uermlnal 7) Is energized. This completes the
10
second
main lIame ignWon trial periOd.
1l'le R7795 is

now
lnthe
normal burner run
mode
of
op-
9rallon
and
will remain
so
until
Btl
aldamal command di-
fecls
il
10
d:l otherwise.
NORMAL SHUTDOWN
Wilen the
burner
con{rof(er opens, the main Ifalve(s)
~erminals
6 and
7)
and
the
bllmer!blower
molar (terminal
B)
are imme;j1ately de-energlzed. 1'h9 R7795

goes
inlO the
stancJ)y
medEl,
t.erminaling the operating cycre.
R7795C AND D
The AT795C
and
0 prolfide the following opgralional
~ce
when
used
wi!h !he
apprcpriale
flame delecror
(R77S5C
req;lres
an ullraviolel OOl6clor, R7795D
re-
Q llres
a re<:lificatlon type OOleclol'). Refer
to
Figs.
36 and
37.
126
The R7795 Primary Control is ready
to
slart
L.P

wheM
lhe
burner controller closes
~imils
are Closed).
With power applied (limits
andcanlroller
elosec:
and
rIO
flaT'na
sil;Tl31
present) rhe
3K
relay
pulls
In and Ihe
burner
molor (terminal 8)
is
energ::r:ed.
As
soon
as
the airflow switch closes (terminals 3
to
B),
the S1795A Pr&pUrge
rlffler
slarts fo lime oul

(prepurge
begins).
NOTE.:
lll9
ST795A Pre-purge
l1mar
relurns
to
zero
any
time
Ihe
airlbw
switch c:pens. The pre·purge restarfs
when
the airflow switch recloses.
PILOT FLAME ESTABUSH1NG PEAIOD
Al
the
end
of
pre-purge (ST795A
limed
out) the 1K relay
pulls
In, sne1gi:r:ing the ignition lranstormef (Ierminal 18)
and the ;nlermltlenl piiOI valve (Iermil'lal
5).
This starts
lhe

10 or 4 second pilot flame eslab1islling peried.
safety
shut-
cbwn
and
lockout
will
occur
If
presence
of
flame Is
nol
proven wllhin:
10 seconds If
the ORANGE jl l'fl)Elr IS
NOT
Clipped.
4
seconds
If
the ORANGE jumper
IS
clipped.
MAIN FLAME IGNITION TRIAL
BASIC DIAGRAM
OF
THE
R7795A
v"

1:\
,
ill
0
ItlTE

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~
,
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.
r::l
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lINE~GE
'SOLATOR
'Ul

t
A"'ll"IR
'LA

1
.1
I
,J,
SOL'OHAT(
OUEUOR
A'R'lOW
SWITC~
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REOVIR(O
FIG.
35-INTERNAL
SCHEMATIC
OF
THE R7795A WITH INTERMITTENT PILOT
At
the end
of
the pilot flame establiShing period
(10
or4
seconds), and with pilol1lame present the main valve
(ter-
minal
6)
is energized:
The R7795 is now In lhe normal burner run
mcxiB
of
cp-
erallon and will remain so until an external command dl-

.
rects it to
do
otherwise.
NORMAL SHUTDOWN
When the burner conlrol(er
~,
the pilot valve
~er
minaI5). the main valve (terminal
6)
and the
bumer,ot!lower
motor (terminal
8)
are immediately de-enerQizad. The
R7795
g::es
into the
stanmy
mocIe,
terminaflng the q:lElr·
ating cycle.
127
71·97558-1
BASIC
DIAGRAM
OF
THE
Rng5C

-
0
~
,~TU'RUPTEO
t
>
"LOT
V"'LVE
.
.,
~
.~
0
,
DELAYED
,
I

,~
v"'c'"
0
'"

'~.
r
FuEL
VALVE
",
-
'"

'"
"
",
t
IlJRNER
,,,
,C"mON
~
,
M/)Ji~R
"
TRANSFOR

ER
'"
»W
"
'"
"
Q
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UW
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UNE
VOLTAGE
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ALARM
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s AND
OVERL,,",O"'O-
Tlet'ON
AS
REQUIRED
ill
ttLECT
A
ROPR'AH
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E OETECTOR
PEA.
T"'LE
II'
FIG.

36-0PERATING
SEQUENCE
FOR
THE
RnS5C
WITH INTERRUPTED PILOT.
'2.
BASIC DIAGRAM OF THE R779SD
0
:lJl
•
'NT~·"UH~D
,
PILat
"",LyE
,.,
0
,
au

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0

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~

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F\ltL
VALVE
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rl
BURNER
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'ABU
FI'.
.,.,
FIG.
37-INTERNAL
SCHEMATIC
OF
THE
R7795D WITH INTERRUPTED PILOT.
129
71-97558-1
, -;,
~
FLAME
DETECTOA
PRI
MARY
CONTROLS

RELAY
-
R7023B,C
R485B
RA890F
RAS90G
RA8S0H
R4795A
A4795D
R7795A,C
R?79SB,D
MOUNTS
ON
C795A
•
•
SUBBASE
MOUtflS
ON
Q270A
•
•
• •
•
•
•
SUBBASE
POWER
TRANSFORMER
-

•
•
•
.(2)
•
•
•
•
•
FLAME SlGNAl. "'
a-RECT
PLUG-IN
PLUG-lN
AMPL.IFIER
C<JV
RECT
RECT
UV
RECT
RECT
RECT
UV
RECT
ORU

OR U

ARC
GAP
PROTECTOR


• •
•
.'

•
FLAME
"RELAY
•
• •
• • •
•
• •
LOAD
RELAY'"
• •
• •
•
• • •
SAfE
START CHECK
•
•
• •
• •
•
•
SA.FETY
SWITCH
•

• •
• • • •
• AEUGKT"
ON
FLAME
• •
.b
eo
eo
FAILURE
"a rrOFF"
ON
FLAME
•
• • .'
eo
FAILURE
SELF-eHECKING
• •
CIRCUITRY
•
PREPURGE
AND
AIR-
FLOW PRO

ING
•
•
•

•
CIROJTTAY
a RECTIFICATION AMPLIFIERS ONLY.
b RECYCLES THROUGH PREPUAGE FIRST.
c FIELD SELECTABlE.
130
PROGRAMMING
CONTROL
FUNCTIONS

PRIMARY CONTROL: FUNCTIONS
The complele
FI~
Safeguard Primary Control per-
forms 3
fUnClJons
as
stlOWn
In
Fig.
1:
1.
It sequences
the
operation-start,
run,
and shut-
down-of
the burner system.
2.

It
supervises
the
pre:senCa
at
a
name,
culling
off
lhe
fuel supply It a flame
'IS
not
present
,
3.
It checks itself against unsafe failure. Typically, il
perfor~a
-salesian
check-
10
prevent burner startuP
if
a
condll1on
'is
present which simulates a flame.
(The
ulll-
male

In
self-checking ability is the Honeywell Dynamic
self
Check system whiCh will be described in the next
section.)
If
a control
does
not
perform
all
01
these functions, it is
not a complete primary control.
FIG. ,
-FUNCTIONS
OF A PRIMARY CONTROL.
The Flame Safeguard Primary Control is
fhe
heart
of
the burner control system.
As
shown in Fig.
2,
II
translates
inputs from the
controller, limits,
and

name
detector
lnlo
sequenced control
of
lhe
burner
motor,
iglillon,
pilot,
and
main
fuel valve(sl.
THE NEED FOR MORE FUNCTIONS
Small
primary
controls,
such
as
the
Rn95,
prOVide
adequate
supervision
10r
small
and
moderate sized burner
systems. Bul, as combustion equipment
increases In size,

so
does
the
potential danger
of
'possible maltuncllon.
More sophisticated systems
are
r9QJired to safely control
large burners
and
bOilers. Burners
wilh
inputs
of
400,000
131
INPUTS
OUTPUTS
CONTROLLER
'u~

~~
M1JTCI~
leNITION
LIMITS
'"
PAIJ

"Y

AI
CONl"Ol
PilOT
VALVE
FLAM~
SIGNAL
"'AINVALVEIII
"
Lc
>u,.,
FIG.
2-PRIMARY
CONTROL INPUTSfOUTPUT$.
Btu
and
over
generally require control sequences more
complex than the R7795 can prOVide.
For
example,
on
large systems, approval bodies require that the combus-
lion
chamber. heat exchanger,
and
flues
be
thoroughly
purged
with air before lighton. In addition, certain mini-

mum airflow rates must
be
used in the
purging
process.
The
ability to
SElQlJence
lhe
purging
must
be
added
10
the
primary control.
More
complex sequences of Ignition
and
pilot Iightoff
musl
also
be
provided
on
larger systems. The pilot must
generally
be
proved before
the

main fuel valve(s)
can
be
opened,
and
the
pilol
may
be
cut
off
~nter~tedl
before
the •
run"
period to
prove
the main
burner
flame.
ADDITIONAL FUNCTIONS PROVIDED BY
PROGRAMMING CONTROLS
Flame Safeguard Programming Controls
perlorm
all
Ihe
fUnctions
of
a primary control
and.

In addition,
add
a
timing
capability thai enables
the
control to sequ9r'lC9
a~
dlllonalfUncllons.
The
name
"Programming
control" Is
often shortened
to
• Programmer, • which is commonly ap-
plied to a primary
conlrolthat
has
a
limer
to extend its
sa-
q.Jencing ability.
A
primary
control, like
the
RA890, performs all its
sa-

QJElnclng fUnctions with relays. The R4795
has
a
si"lJle
timer
10
prOVide
limed
prepurge only. A full programmer,
like
the R4140.
has
a synchronous motor-driven rimer with
8to
12 cams, each controlling 1
or
2 sets of switching con-
tacts.
The
BC7000 goes further slill, providing microcom·
puter control
and
features
beyc:nd
the capability of
conventional electromechanical
or
discrete solid-state
conlfols.
All programmers are desi(;11ed to provide com-

pletely auh:malic
burnet
conlrol.
In
acrmlon
10
Ihe
inpuls and outpuIs
of
a primary
cen-
tral, InterlockS are ad:iBd
as
IrpJIS
(Fig. 3),
and
firing rale
SWit~hing
clr~uits
are act:ted
10
the outpuIs. Also, the
1(;111-
tlon, pllOl,
and
main valve<s) are
limed
t7f
the
progrsrrvner.

7HI7558-1