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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 UAFLAME ~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

'G ILKTIONIC u-+

U(TlFY OT)POWEI N(TWOU: HAMl SUPPLY

100. ,,-+

' ...oto

0 .. (7012A,(,

FIG.2 SIMPLIFIED SCHEMATIC DlAGRAM OF

AN R7023B.

71-97558-1

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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(

WHITE II Wf'WOII.

• ,

10AD-N.0.

LOAD·N.t.

tOMMON

'0

tl017A,

tl0UA, u-+

O. IHOT)~OWU

t1044A iU'~l1"

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.

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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 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

... :;

FLAME CURRENT '/ . Il' 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