FLAME SAFEGUARn CONTRULS phần 4 pptx

- 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.. the ignition and pi

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 1K1 opens,

dEHnergiz-lng Ihealarm (lermlnal3J Contact 1K2 closes, bypassing

the safe start contact (2K1), and 1K3 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 1K3 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 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

de-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 C O N T R O L S

-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

0:270 SUB6Alif • F\.Ulf s.o.Fn'l'

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

•

•

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

TO fLAMl - •••

FIG 6-RA890F IN tHE STANDBY POSITION

2NC·STAQE Oil VALVE

(1' USEOI 1A8'O

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

- 1K2 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( . - = =-=:" _-_

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

"'lOT D llI_mON .IIO_.IU ~

FIG.9 RA890,F OPERATION WHEN RELAY 1K

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

An; time relay 1K pulls ln, terminal 3 wlJi be powered If

1K ISIn 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 1K2 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-off cyCle

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 off, Including pilot, is rEq.Jired for LP gas

shut-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 valveIs) 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

THII·

~ r1t, ~l: RA890F TO MISlO(

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 C7027A 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

model, 1 Iransformer powered bolh circuits from terminal

1 However, a line voilage controller could not be used 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.)

be-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 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

control-an oil system, the burner motor control-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

- 1K4 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 stage oil valve} from terminalS The main burner lights

second 21<3 opens; !he safety swilch heater stops healing

RA890G -STAIIDBY POSITIOII

llU HI TI~

211 "'LAM IlnAYJ Til'

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 slaga oil .alVQ (IermTnal 3) and the main valve(s) 0(

fjrsl-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 ond-stage oil valve (lerminal 5)

sec 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

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

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

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 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

sel1-check-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

Other differences from the RA890F are in the low age relay logic circuit More COl'Tl'lax switChing requires

volt-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) facllon o11heGalifor heat

satis-(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 eraUon using a line voltage controller differs from the op-

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 1K4 closed, relay 2K can pullin when 4K4 closes (4K pulls in when flame is detected)

RA890H·CALL FOR HEAT

(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

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

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

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)' sition The burnef cannot be started again untillhe saf9ty SWilCh on the RA890H Is r8SEl1 rTlBnuallry

p0-(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"

, ','

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

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

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) not c:pen lh8 safety switch healer will continue 10 heat; safety shuldown will occur In abcul 15 seconds

can-Durina the -Run- Period

It the cOIlW"l9'1I failure occurs during the -run- riod, the RA890H will c:perate the same as It the flame

pe-goes oul (see Fig 25, condition 3) Relay 4K drq:m out, energiZing relay 1K Opening at 1K1 dB-energlzes the pilot valve and main V81ve(sj The safety switch heater will be-gin heating; safety shuldown wilt occur in about 15

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 vern the system from cycling ~!' the limits, and 10 en-

pre-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 ference from lhe normal hookup for an intennil1ent pilol is

dif-in the location of the controller The controller is connected

in series with the main valve(s), so power Is applied tinuously to terminal 6 through the limits A line voltage controner Is used, so T-T Is ~red

RA890H SAFETY OPERATION

I.UE START CHiclC

• 'L"'''''I IDP n III.U1.4 C'OI ""UIf<T AT STARTVI'

• PRlvl u n 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

Tn",.T", O V" l ou.,,,,, "AUN" P~AlOO !TY lil'lUTlIOfI"

LIMIT ACTION, OR MOMfNTARY POWfR FAILURE

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 down occurs 1he controller cannot inler~tlK, so there will be no more safe SIan ctIecks

shut-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,

Therest of the safety OperationIsthe sameasfor

inter-millenl pilot q:orBllon

FUP-FLOP -tIRCUIT WITH SAFE STAAT

I~ "f, ,~ WITH SAfE START CHECK

-oNCAll FOR HUT

FLIP-FLOP RELAY CIRCUIT TO

PROVIDE A SAFE START CHECK ON

CALL FOR HEAT

To provideasafe st;:t.rt check Yiheoevar thereIsa call

for heat, the flip-flop refay circuit shown in Fig.29can be

usee! A line voltage controller is again used, soT-Tis

jum-pared.TheR48ZF Relay is between the conlrollerand

ler-rninaI 6 The3K3 relay coolacls are between terminalS

and the main valve(s).ThepilafIsnot strlCl1y a coolinuous

piiOl asIt is lurnedoffand 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::IWEIrisapplied to lerminal 6 through the IImil(slandc~

tacl3K1 of the R482F Relay During the "run" pariod, 3K

of the R48ZF Relay is pulled-in; power is applied to

lermi-nal 6tht~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 Closingof1Kl 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 TheIlame relay 2K

pulls In when 4K4 closes Contact 2Kl opens,

dlHInergiz-lng the 117'ItiOf1 (terminal 4) If the pilolQC)QSout,safety shut

down occurs So far, the operatiOllls exacffy the same as

for the previous hookup shown in Fig 26

On a call for heal, the conlroller closes Retay 3K In lheR482F pullSinthrough lhe thermistor Conlact 3K1 in theR482F operis, removing power from terminal 6 of lheRAB90H All relays In the RA890H drop oul, and the pilotgoesout.After a short delay(c:lleto the thermistor), con-lact 3K2 In the R482F closes, reapplying power to tl:\rmlnal

6ofthe RA890H Contact 3K4 In lhe R4B2F closes, passing the thermistor Contact 3K3 Inthe R482F closes,connecting Ihe main val -e(s) to lerminal5of the RA890H From lhis lXlint, the stan\ Pand the "run" paried arethesame asfor the normal cperalion of an RA890H with

by-anIntermillenl 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 Uschecking actionand4K pufls in Contact4Kl cpens, so theload relay 1K camot pull In (delayed by the thermistor) and

provided every time there Is acal~for heat by momentarilyinterr\ pting power 10 the RAB90H Ihrough the R482F Re-lay The pilOt Is turned off while the check Is made, andtherl re-ignilecL

If no flame (nor flame-simulating conditlon) Is delected,theloadrelay 1K pulls In Closing of 1K1 energizes the pi-lot valve (terminal 3), and lhe pilot Is ignited When the pilotflame is delected, the flame relay 2K pulls in Closing Of21<2 energIzes the main valv&(s) (terminal 5) The mainvalve(s) opens and Ihe main burner is Ii!

When lhe call forhealis satisfied, the controller opens.Relay 3K in the R482F dropsout. Contact 3K3 in lheR482F opens, de-eoergizin;l the main valve(s) (te[minal5) The main valve(sj closes, and the main burnergoes

oul Contact 3K2 in the R462F opens, removing powerfrom terminal 6 of the RA89OH All relays in the RA890Hdrcp oul

Opening01 1K1 de-energizes the pilot valve (lerminal3) and the pilO! goes oul Contact 3K4 in the R482Fopens, removing the bypass from Ihe thermistor When3K1 in the R482F closes, power is reapplied to terminal6

of the RA890H The load relay 1K purls in, 1K1 closes, thepilot valve opens, and the piiOI is ignited Whentheflameisdetected,lhe flame relay 2K pulls In, 2K1 opens, and theignition turns off The conllnuous pilot has been re-established _

SafetyOperation

A safe start cheCk Is prOVided every llme there Is a Callfor heal.TheR482F relaylnterr~tspower to the RA890H.All relay contacts in the RA890H return to the stanct>ypo-siUon,andthepllolgoes out.After a short delay, power isreapplied 10 the RA890H If a flame (or afla~lmulating

COndition) is detecled, relay 3K In the RAB90H starts itschecking action and 4K pulls in Cor;tact 4K1 opens, pre-venting the load relay lK from pulling in (delayed by thethermistor) The syslem carY"lOf be started

Therest 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 Foperating with a continuous pilot Onthe rest of themed-als,11a flame (or a cOndition simulallng a flame) Ispresent

at startup,the load relay lKcannot pull In The startupoperation cannot continue until the 'lamegoesoul oruntilthe tlame-slmulallng ceroillon is corrected safety shut-down will occur for lhe RA890Gonly

On limit actlon or momentary oower failure, all modelsrecycle They restart wnen normal conditions are restora:::land all manual resel limils are reset, If necessary.SAFETY SHUTDOWN

If the safety swllch healer is altowa:::lloheat for a clent perioo(15or30 secondS,depending on themodal),the safety switch contacts will open and the load relay1K

sufIl-will drop out, Terminals3,4,and5(pilot valve, ignition, andmain valve) willbede-energizecL AlI1ue1 valves will close.Thesystem cannol berestarted until the safety SWilch isreset manually The operator must wait at least 1 minutefor the heater 10 cool before pushing in the safety switchreset bullon in the cover

safety shutoown occursif:

- a flame(ora flame-simulating condition) is presenl atstart up, for the RA890G only

- no flame is established, tor all mcdels

-the flame Is not re-establishad after il goes out andthe ignition is energized again to try to relight theburner (called ~rellg.t~or "ignition relurn"), for theRA890E,F, or G

- the flame goesout during Itle ~run- perlooard noatlelTp( is made to r&-light (-eutort"), for lheRA890H

TABLE II-COMPARISON OF R890 OPERATION.

Jrf'f'UCA,TIOHS: RAnOE RAnOf RAnoa ~"

INl'EAl'\lJFI"ED Of\ INTER- • • • •

MTTENT IGNITION

0'" a.P oWTOM,AT COfol71HUOUS PLOT

'"""'" , 0'

"""'" '"

"""''''"'SAFESTAATCHECl< • • • •

RE'CYa.ES ON UMrT ACTlON Of\ ~Ot.IENT Mff • • • •

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 intheelectronic network causes safety shutdown

The type 01 flame sIgnal amplifier in lhe RA890 is Incll·

cated In Tabler. RECT indicates an amplifier for use with

reetificatlol1typeflame cIeleclors These include reclifying

flamerods, rectifying photocells, and C7012A or C Purple

peeper Ultraviolet Flame Detectors A flame rocl is

recom-mended for usewiththe RA890H The Uv amplifier, inthe

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 01lhesyStem-:The

arc gap will glow i1 interference is severe thus providing a

visual Indicallon 01 Ignition interference

Theplastic 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 loadandflame relays,

which could result In an explosion

The areen flame signal light blinksWhenthe flame

de-tector -sees" the flame, indicating that the self-cheCklng

circuitry is wor1<ing property

APPUCATlONS

All mcdels canbeused 10 provide either Intern -pted or

intermittent ignition, and Intermittent pilot A continuous

pilot can be used with-an:

- RA890E, 11you remove the jumper screw

- RA890F,ityou ~the pilol link jumper wire

- RA890H jfyou use an automatic (electrically

operated) pilot valve and one of the special hookups

RAIIOE RAUOI'" RAuoa Fl GH

SOUD STArr;: CIRCUITRY • • •

SEl.F-CHEa<JNG CIFlCUlTRY •

R.A/olE SIGNAL AMPLIFIER AECT

""

IlAC aN' PROTECTOR • •

F'l ASTIC COVEfl aVER RElAYS •

GAEEN FL.WE SIGNAL UClKT •

- a COl'J"4XlOOl1t fails In the electronic nel'NOrk ofthe

RAll9OH

UPDAnNG·RA800 INSTALLATIONS

UpdallnganRA890installation with an RA890H results

Intheao:1itionalfealures listed In Fig 30. If'seasy10

ra-place an RA890B.C,E.or F No changes are required Inthewiringtolhesut:O&se;simply remove the old conlrol

andmount thenewone If a cutoff circuit wasusedIn Iheold installatioo it is nol necessary to remove the externalcutoff relay However, the RA890H iflcorporates ·cutoff,·

sothesuttlaSEImay be rewired 10~!imlnale the sary external cutoff ralai', If desired.If the hot line (L1) is

unneces-CO'1(}Ar,!ed 10lelminal1in fheoldInstallation, It maybe lettconnected, even though it Is not required to operate IheRA890H

FIG 30- UPDATING RA890 INSTALLATIONS

WITH THE AA890H

R4795 PRIMARY C O N T R O L S

-ThElsecontrolsU&emuchof the proven, reliable

hard-W31saroci1cullryo1 the RA890's Inaddition, 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 R479510beused with e:ther

rectification or ultraviolet type flame detectors However

R479S's~prOYipe-the setf-Checking feature included

in theRA890H

TheR4795A provides· recycle.~ If the namegoes out

'during lhe "run- period, the A4795A w)l) recycle oncs

Ihrough pre-purge and try to establish the pilot If the pilot

flameis 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 nhas an ao:1ltional cutoff relay (41<) in

lhe lower right cornet in 1ronl of Ihe Iransformer

APPLICATIONS

TheR4795A and0 Frame safeguard Primary Controls

providesolid Slate, electronic, flame safeguard protection

forcommercialandIndustrial gas or011 burners They are

designed for intermillent pilot appllcallons lhey Cannot

beusedfor interrupted pilot applications without external

circuitry

TheR4795A 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 or90second

pre-purgelimer isused

The R4795D Is designed foruseon power burners rect· or indirecl·fired), makeup air heaters, and spaceheaters Itmeets Factory Mutual and Factory InsuranceAssoclalionIF.I.A.) requirementslormak.eup air heaters

(di-

FIG 31 -COMPONENTS OF THE R4795A

FIG, 32-SCHEMATlC DIAGRAM OF THE

R4795A OR D WI'Tli THE POWER OFF

QPERATION

The cperation01 the R4795A is similar to thatoftheRAB90F except for the actlitional pre-purge function.0p-eration of the R4795D is the sameas that of the R4795Aexcept that11provides "cutaW instead of~recycle" iftheflamegoesout durirlQ the ~run" period

Fig 32 shows!he schematic diagram tor the R4795Aor

D wilh the master switch cpen and the poweroff.Because

at ils complexity, the internal, low voltage, relay IOQlc cuitry is nolshown.The plug-In purge limer Ispartof thelow vollage circuitry.TheR479SD differstromthe R4795A

cir-FEATURES

In actlilion to RA890 features, the R4795A and D

in-clude (1) plUQ-in purge timers,(2) circuitry for proving

air-flow, and13) plu~jn flame signal arrpUfiers The plug-incomponents are easy10replace, resulting in faster service

and reduced inventory

(1) The solidsTa!.e','·pfug-lnpurge IImerscanbeordered 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

switchts.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 beUSed withrectification or ultraviolettypeflame tors The R7.289A Rectification Amplifier, wilh a greenbackplate, is tor use with rectifying flame rcx1s, rectifyingphotocells or C7012A,C Purple Peeper Ultraviolel FlameDeteclors It also contains an arc gap protector similartothe one in the RA890F and H The R7290A Ultraviole!

detec-Amplifier, witha purple backplate, is for use with C7027A,C7035A, or C7044A Minipeeper Ultraviolet FlameDetectors

Other features, also included in the RA890's, are solidstate circuitry, optional lerminals for an external alarm,and a Ilame currenllest jack(on the plug-in amplifiers)

R4195A SAFETY OPERATIONSa'ety"CflSrallon can be divided Into6conditlons-(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 powerfailure

atlerrpl 10 re-Il""t) about 15 seconds after the aa1Btyswitch healer begins heating.Thesafety switchcartacts

only in an actlitional cutoff relay (4K), whIch is also In·cluded in the low voltage cIrcuitry

Terminals a, 7, and6on the 0270 Slbbase Oabeled Inyellow) are used 'or the R4795.Thesearethesametermi-nals laDelBd6,T, and T (In while) used tor (he RA890's.The external hCX;Ikup shown is 'or agassystem Foranoilsystem, the first·stage oil valve and burner motor replacethe pilol valve on terminal 3, and the SEtCor'd-5tage oilvalve (i'used) replaces the main valve(s)onterminal 5.(see Fig 7)

TheR4795 uses terminals 3, 4, and 5exa.ctly the same

asthe RA890's However, power Is awlled to terminal 1inslead 01 terminal a (6 on the RA89Q's) Terminal aIsused for the burner motor (fan or blower) to provide thepre-purge function An airflow swilCh Is connected be-tween lerminals6and 7(TandTon the RA890's) There-fore, a low voltage controller canoot be used with theR4795

The ignition sequence relay contacts are nurrbered ferently than for the RAB90's-1K4, 2K2, and 21<3 Instead

dif-at1K1, 2K1,arrl2K2 respeclively Otherwise these

con-(acts perform the same funcllons Also there isanackli·tional 3K2 contacl between the hal line (L1) ard the othercontacts

NORMAL OPERATION (R4795A OR D)During lhe stancby period with the master switchclosed,00power Is applied to the R4795 sincethelil'\8vottage controller Isopen

On a call for heat, lhe controller closes If aJllimils areclosed, the transformer secondary energizes the low volt·age relay~CirCUitry Relay 3K will PJIl in through thesafety switch heater proving ils continuity Contact 3K2closes, energizing the bumer motor (terminal8).When airflow is proven and the airflow switch closes,the flame signal amplifier Is energiZed and lhe PJrge timerstarts At the end or the pre-purge, relaylK PJIIs In.C0n-tact 1K4clO68S, energizing the pllol valveandignificn(Ier-minals 3and 4), and thepilol ignites The saf9ty switchheaterwillbegin healing,

Wh8'I the flame deteclorsenses the pilot ftame, theRame relay 2K pulls in Opening of 2K2de-energizesthe1001110n~ermlnal 4) Closing of 2K3 energizes the mainfuel valve(s)~ermlnal 5), and the main burner iglites Thesafety switch heater stCflS heating, and the PJrgB llmer Isresel.Thesystem IsnowIn thearun " periodwllhthemainburner firing

When the bumer SlWllesetlCJUI;tlheat,thecontroller

slanchy position

, -,

.'''''''',1; " " , "",""-,,,.

can-(1) Safe Start Check

Ifa, flame (or a flame-slmulating cc:nc:litlon) Is presentwring the pre-purQ8 period.: relay 2K pulls In Internal re-laySWIlChil')gwillr9ffiO\le fX)Wer from the purge timer ThetlmerwllJ step, sothaithetoad relay 1K cannot pull In C0n-tact 1K4eat'IDOl.close, so the pllOI cannotbe1~lled.Theburner motor wlU call1rue to run, providing a call1nuouspurge (sate rallur~. The start upq:lEIration cannot con-tirue unt1llhe flameg:l9Sout or I.I'ltillhe flame simulatingCO'ldItlon is correcled

(2) Purge'Tlmer FailureIflhe pluiln purQ8 llmer IsnoIproperly Installed, or Isnol MClionlng prq:lElrly pre-purge cannot be completed,

so the load relay 1K cannol puJlln_ Contacl 1K4 cannolclose, so the pilotcannolbei~lted.The burner motor willconIirue 10 run, providing a continuous purQ8 (satefallure)

(3) Airflow Failure

Ifairflow Is not prOV9I1, the airflow switch w!tl nol closea.-.:j pre-purge cannotbestarted If airflow falls wring pre-purge, the airflow switch willopen,the timer will stop, and

pre-pu~camoIbecompleted 11 aIrflow fails wring the-rt.rI-period, Iheairflow swllch will open and all relays6X-cept 3K will dropout.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, lhepurge timer will start, ardthe stan~opsration will beginagain with pre-purge

(4) No Flame EstablishedRelay 1Khasalraaety pulled In, so the sa1ety switch ishealing; contact 1K4 Is closed, so the pllot valve andI~i.

tion (terminals 3 en::! 4) are energized The pilotlXlElS nol

""'lie, so the flame deleclor senses no flame The flamerelay 2KcannoI:pullin Ga'ltaol 2K3 will nol close, so themain valve(s) (Iermlnal5)cannolbeenergized The satety

switch will conliruetoheat LrllU safety Shutdown occurs

On abOUt 15S&CO~.

(5) Flame Goe Out During the "Run" PeriodWhen the flame detectorstepssensIng a flame, Inter-nal SWitching causes boththeflamerela~2K en::!lhe loadrelay 1K to drop out Conlact1K4 opens to dEHlnergizeter-mlnal& 3 4,ard5 Tnapilot valY8andmain valve(s) willclose It the airflow is stlll proven, lhe purge timer will startand pre-purge will begin After pre-purge, 1 aUerrpt willbemade tore-lighl the burner Relay 1K will pull in, lhesatetyswitch heafer will begin· healing, and conlact 1K4 wiltclose The pilot valve (terminal 3)ardIgnition nenninal 4)will beenergiZed If the pilot flame Is not re-established,safety shutdown will occur

(6) Umlt Action or Momentary Power Failure

If a limitopensbecause ofan abnormal condition, itq:lEIns the power line(L1)fromthe master switch to lermi·nal 1 A momentaryfX)WEll'1allure would likewise removepower from terminal 1 Loss ofpower da-energizas thetransformer All relays drq) outardthe contacts return 10Ihe stan:;I)y position (same as In Fig.32).AU automatic fuelvalves close ardthe burner molar stops running Whennormal conditions are restored, the limil(s) closes and/orfX)Wer is restored to tenninal 1 The system will restartand

operale normally

NOTE: The useofmanual reset limits is desirable to vent the syslem from cyCling off lhe limits, and 10en-sure that the condition which causes the Iimil action isdatecled as soon as possible

pre-R4795D SAFETY OPERAnONSafety q:lEIralion for the R4795D is the same as for theR4795A except for lhe following conditions

In the sate start check, If a flame (or a flame simulatingCondition) Is pr6S9f1t wrlng'lhe pra-purge period internalrelay 4K (the· cutoff- relay) will also pUll In, causing thepurge limer 10 stq) and the safety switch healer to beginheating Safety shuldown will occur In aboul 15seconds

11 the flamegoesoutd.Jring lhe -run- period, internalswitching causes • cutoff - The R4795D will not recyclethroug pre-purge No allllllTf.ll willbemade to re-Iighltheburner before safetyshutOOwnoccurs

R7795 PRIMARY C O N T R O L S

-The Rn95 Is Honeywell's most complete primary troL All models have Integral flame arrpllfiers nhe R7795Aand C are for ultravlolel delecllon systems, the Rn95Band 0 are for recllflcation delecUon systems), and twofield-selectable fealures allow unlq.Je Inslallallon YElrsatll-Ity The Installer can selecl100r 4 second trial forpj~~

con-lloii and recycle(l(lockOutoperation onflamefailure

Solid stale pl1.Q'In ST795A Purge TImersusedwith lheR7795 provide pre-purge timingsof1.5, 7,10.30,60, ar90seconds A safe.start feature preventsstart~wllh lockout

Ifaftarneor a flame &tmulallng failure exists

Olher fealuresofthe R7795 Include terminals for

con-necllng a line voltage airflow switch 10 prove airflow from

the start of the pre-purQ8 throug the run period meterjack for measuring the flame SI\Tl81 while the syslem is inq:lEIration, a powered alann t8lTT\lnal to q:lEIrale an exter-nailine vollaQ8 alann or safety lockoul,anda manual resetsafety switch

The Rn95 Is sl"cwn in FltlJre 33

APPLICATIONS

The Rn95 Flame SafeQ.J8rd Primary Ga'ltrols provide

f1ameou1protecllon plus automatic control of commercial

andlnc:1Jstrlalgasand otl burners The R7795AardBare

cla:slgnedfor Intennltlent pllot applications The Rn95C

Q7!J5A

WIRINGSUBBASE

/ST79SA PREPURGE TIMER

COVER

FIG 33-Rn95 SYSTEM COMPONENTS

andD are designed for interrupted pilot with delayed main

valve applications., A tun-test switch is provided on the

R7795C 8Jld D

All models meet Underwriters Laboratories Canadian

Sfandards Associalion.andFaclory 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) andinler~edpifol mOdels (A7795Cand

D)are shown in Figs.35 and37

R7795A AND B

The Rn95A and B provide the following cperational

sequence when used withtt'eapprq:lrlate flame deteclor

(A1795A requirQS an ultraviolet deteclor R1795B r9QJires

a rectification type deleClor) Refer to Figs.34and35

The RT795 Primary Control is ready to start up when

the burner c:onlroller closas(limits areClosed)

With p;:lwerapplied(limits and c:or,lrofferclosed and no

flame sigial present) the3KrelaypullSinandthe burner

roofor (terminal8)isenerQi:zed '

Assoon as the airflow switchcloses(tennlnals:3to8)

andwith /he RUNfTEST switch In the RUN posilioo, the

AI theendc1pre-purge(ST795Alimedout)the1Kand4K relayspull in, simultaneousi)' enBrg-:zing theigllUc.ntransformer (terminal 18) and the Interllfllecl pilot valve(terminal5) Thisstattsrile10 or4seccndpilOI flamees-tablishingperiod.Safety shutctJwnandloCkoutwilloccur

itpresence atnameis not proven within:

10 secondS 11 the ORANGE tumper IS NOTCII~

4seeonds it fheORANGEjun'plrIS Clipped.

If the RUNfTESr switCh is movecl to theTESTposlllon

wringthe pilo!:flame astabli5hingperiod,thesequence Is

slq:Jped in trial for pilotflame The safetyswItch healer Is

enerQzeddurlnqfhispilotflame establishingperiodever flame is not present safety shutdownardlockoutwilloct;ur il lhe absant:e 0' flame exc~ 15 seconds

Mlerl-(nominal)

MAIN FLAME IGNmON TRIAL

Attheardc1lhepilot flame establishing period (10or4seconds), wilh pilot ffame present, ard the RUNJTEST

71-97558-1

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l!:.H 'NAU UC DU" '[D AS CIACUONU BER5(0 )

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FIG 34-0PERATING SeQUENCE FOR THE R7795A AND B WITH INTERMITTENT PILOT

switchIn,heAUNPOSliion, lhe Ignition iranstormer

!laml-nal 18) is de-energized and the main valve (termi!laml-nal6)is

energized staning Ihe maIn Ilame Ignition trial Ten sec·

onds intofhemainflame Ignitiontria)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'leR7795is nowlnthe normal burner runmode of

op-9rallonandwillremain so untilBtlaldamalcommand

di-fecls il 10d:lotherwise.

NORMAL SHUTDOWN

Wilen the burner con{rof(er opens, the main Ifalve(s)

~erminals6and7)and the bllmer!blower molar (terminal

B) are imme;j1ately de-energlzed.1'h9 R7795goesinlO the

stancJ)ymedEl, t.erminaling the operating cycre

R7795C AND D

The AT795C and 0 prolfide the following opgralional

~cewhen used wi!h !he apprcpriale flame delecror

(R77S5C req;lres an ullraviolel OOl6clor, R7795D

re-Q llres a re<:lificatlon type OOleclol') Refer toFigs.36 and

37

The R7795 Primary Control is ready to slart L.PwheMlhe burner controller closes ~imilsare Closed)

With powerapplied(limits andcanlrollerelosec:andrIO

flaT'na sil;Tl31 present) rhe 3K relay pulls In and Ihe burner

molor (terminal8)is energ::r:ed

As soon asthe airflow switch closes (terminals3 toB),

the S1795A Pr&pUrge rlffler slarts folime oul (prepurgebegins)

NOTE.:lll9ST795A Pre-purge l1mar relurns to zeroany

time Ihe airlbw switch c:pens The pre·purge restarfswhentheairflow 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-cbwnand lockout will occur If presence of flame Is nolproven wllhin:

10 seconds Ifthe 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

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 mcxiBof

cp-erallon and will remain so until an external command

dl- rects it todootherwise

NORMAL SHUTDOWNWhentheburner conlrol(er ~, the pilot valve~er­

minaI5) the main valve (terminal 6) and the bumer,ot!lowermotor (terminal 8) are immediately de-enerQizad TheR7795g::esinto the stanmymocIe,terminaflng the q:lElr·ating cycle

BASIC DIAGRAM OF THE Rng5C

- 0 , ~~ > "LOT V"'LVE,~TU'RUPTEO

illttLECT A ROPR'AH 'L E OETECTOR PEA T"'LE II'

FIG 36-0PERATING SEQUENCE FOR THE RnS5C WITH INTERRUPTED PILOT.