Fig. 26. RM7838B,C Relay Module operation.
INITIATE
POWER
LED
DISPLAY
PILOT
FLAME
MAIN
ALARM ALARM
STANDBY
(INDEFINITE)
POWER
ALARM
POWER
DRIVE
TO
HIGH
FIRE
DRIVE
TO
LOW
FIRE
5
SECONDS
MAX
2010000000 00
10 SEC 10 SEC
HOLD
(INDE-
FINITE)
HOLD
(INDEFINITE)
J3 INTACT
PURGE
PURGE TIME IS SELECTABLE
THROUGH VARIOUS
ST7800 PURGE TIMER CARDS
PFEP
J1 INTACT (10 SEC)
J1 CLIPPED (4 SEC)
MFEP NORMAL
BURNER
RUN
RM7838B/C ENERGIZED (TERMINAL 4 AND L2)
TERMINAL 3 ENERGIZED (ALARM)
TERMINAL 6 ENERGIZED (LIMITS/STOP SWITCH)
LF SWITCH CLOSED (TERMINAL 18)
HF SWITCH CLOSED (TERM 19)
PREIGNITION INTERLOCKS CLOSED (TERM 20 ENERGIZED)
SAFE START CHECK
TERMINAL 13 TO 12
TERMINAL
13 TO 15
TERMINAL 13 TO 14 TERMINAL 13 TO 14
TERM 10
TERMINAL 5 ENERGIZED (COMBUSTION AIR FAN)
TERMINAL 7 ENERGIZED (COMBUSTION AIRFLOW SWITCH)
TERMINAL 8 ENERGIZED (J2 INTACT)
FLAME PROVING
TERMINAL 9
TERMINAL 8 ENERGIZED (J2 CUT)
MAIN
PILOT
FLAME
POWER
MAIN
PILOT
FLAME
POWER
MAIN
PILOT
FLAME
POWER
M23680
2
1
2
1
1
1
ALARM IS OFF FOR RM7838C.
ALARM (TERMINAL 3) IS DE-ENERGIZED AS SOON AS FLAME IS DETECTED (RM7838B ONLY). (OFF FOR RM7838C)
NORMAL SHUTDOWN OCCURS WHEN TERMINAL 6 IS DE-ENERGIZED.
15 SECONDS FOR RM7838C.
3
4
4
3
PFEPEGRUPETAITINI
ALARM
POWER
NURPEFMTRATS
TERMINAL 21 ENERGIZED
(IGNITION)
(INTERRUPTED
PILOT)
(INTER-
MITTENT
PILOT)
(MAIN
VALVE)
OPERATING
CONTROLS
AND
INTERLOCKS
FLAME
SIGNAL
FIRING
RATE
MOTOR
BURNER
5
VALVE PROVING OCCURS CONCURRENT WITH PURGE IF “BEFORE”, “BOTH”, OR “SPLIT” SELECTED.
6
VALVE PROVING OCCURS HERE IF “BOTH” OR “SPLIT” SELECTED.
7
POSTPURGE OCCURS NOW IF SELECTED. VALVE PROVING WILL ALSO OCCUR CONCURRENTLY.
8
COMBUSTION AIR FAN AND AFS REMAIN ON FOR COMPLETION OF VPS AND/OR POSTPURGE IS COMPLETE.
5
6 7
8
8
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