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7800 SERIES RM7824A RELAY MODULE
65-0155—1
11
CAPTIVE
MOUNTING
SCREW
DUST
COVER
RELAY
MODULE
FLAME
AMPLIFIER
FLAME CURRENT
TEST JACK
FLAME
SIMULATOR INPUT
SEQUENCE
STATUS LEDS
RESET
PUSH-
BUTTON
M7593
Fig. 13. Sequence status LEDs.
Initiate
The RM7824A enters the INITIATE sequence if the Relay
Module verifies voltage fluctuations of outside 22 to 28 Vdc
during any part of the operating sequence. The INITIATE
sequence lasts for ten seconds unless the voltage tolerance
is not met. When the tolerance is not met, a hold condition will
be initiated and will be displayed on the optional Keyboard
Display Module for at least five seconds. When the tolerance
is met, the INITIATE sequence will restart. If the condition is
not corrected and the hold condition exists for four minutes,
the RM7824A will lock out. Causes for hold conditions in the
INITIATE sequence are:
• Vdc dropout is detected.
• Internal timing functions are not synchronized.
• The noise that can prevent a sufficient reading of the low
voltage inputs.
• Brownouts caused by low input voltage.
INITIATE
STANDBY
STANDBY
HOLD: F/G
(FLAME
DETECTED)
POWER
PILOT
FLAME
MAIN
POWER
PILOT
FLAME
MAIN
PILOT
IGNITION
SAFE-
START
CHECK
ALARM
POWER
FLAME
MAIN
PILOT
ALARM
ALARM
POWER
FLAME
MAIN
PILOT
ALARM
POWER
FLAME
MAIN
PILOT
ALARM
POWER
FLAME
MAIN
PILOT
ALARM
POWER
FLAME
MAIN
PILOT
ALARM
RESET/
ALARM
TEST
RUN
M3362
Fig. 14. LED sequence status display information (see Fig. 13).
Standby
The RM7824A is ready to start an operating sequence when
the operating control input determines a
call for heat
is present.
The burner switch, limits, operating limit control and all
microcomputer monitored circuits must be in the correct state
for the RM7824A to continue into the SAFE-START CHECK.
Normal Start-Up Safe-Start Check
The RM7824A verifies that a flame does not exist and
proceeds into the ignition trial. If a flame is present, the
RM7824A will recycle to the STANDBY period. If the critical
loads are not in the correct state, a safety shutdown occurs.
Ignition Trials
Pilot Flame Establishing Period (PFEP):
1. The pilot valve and ignition transformer, terminals 8 and
10, are energized. The RM7824A has an intermittent
pilot valve, terminal 8.
2. Flame must be proven by the end of the 4 or 10 second
PFEP to allow the sequence to continue. If flame is not
proven by the end of PFEP, a safety shutdown occurs.
3. With flame proven, the ignition, terminal 10, is de-
energized and the main valve, terminal 9, is energized.
Run
The RM7824A is now in RUN and will remain in RUN until the
controller input, terminal 6, opens, indicating that the demand
is satisfied or a limit has opened.
Selectable Site-Configurable Jumper
The RM7824A has one site-configurable jumper option, see
Fig. 15 and Table 4. The site-configurable jumper should be
clipped with side cutters and the resistor removed from the
Relay Module.
Fig. 15. Selectable site-configurable jumpers.
SELECTABLE CONFIGURATION JUMPER
M7592