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Fig. 13. Release Reset screen.
Changing the postpurge time feature is still possible. With
the RM7897 in Standby, scrolling to the Setup line and
entering with the password allows the settings to be
changed.
Once the system is in operation, the settings of the
postpurge time can be viewed under Diagnostics, using
your S7800 Keyboard Display Module.
PRINCIPAL TECHNICAL
FEATURES
The RM7897 provides all customary flame safeguard
functions as well as significant advancements in safety,
annunciation, and system diagnostics.
Safety Shutdown (Lockout) Occurs
if:
1. INITIATE PERIOD
a. Purge card is not installed or removed.
b. Purge card is bad.
c. Configuration jumpers have been changed (after
200 hours)—Fault Code 110.
d. AC line power errors occurred, see Operation.
e. Four minute INITIATE period has been exceeded.
2. STANDBY PERIOD
a. Airflow lockout feature is enabled (JR3 clipped)
and the airflow switch does not close after ten
seconds or within the specified purge card tim-
ing.
b. Flame signal is detected after 240 seconds.
c. Ignition/pilot valve terminal is energized.
d. Main valve terminal is energized.
e. Delayed main valve terminal is energized
(RM7897C).
f.
Internal system fault occurred.
g. Purge card is removed.
h. Purge card is bad.
i.
PreIgnition Interlock open.
3. PREPURGE PERIOD
a. Airflow lockout feature is enabled (JR3 clipped)
and the airflow switch opens.
b. Ignition/pilot valve terminal is energized.
c. Main valve terminal is energized.
d. Delayed main valve terminal is energized
(RM7897C).
e. Internal system fault occurred.
f.
Purge card is removed.
g. Purge card is bad.
h. Flame signal is detected for 30 seconds.
+
M22765B
RM7897A,C 7800 SERIES RELAY MODULES
i.
Preignition interlocks open during standby.
4. PILOT FLAME ESTABLISHING PERIOD (PFEP)
a. Airflow lockout feature is enabled and the airflow
switch opens.
b. No flame signal at end of PFEP.
c. Ignition/pilot valve/intermittent pilot valve ter-
minal is not energized.
d. Main valve terminal is energized (RM7897A).
e. Delayed (second stage) main valve terminal is
energized (RM7897C).
f.
Internal system fault occurred.
g. Purge card is removed.
h. Purge card is bad.
5. MAIN FLAME ESTABLISHING PERIOD (MFEP)
a. Airflow lockout feature is enabled and the airflow
switch opens.
b. Ignition terminal is energized.
c. Ignition/pilot valve terminal is not energized.
d. Main valve terminal is not energized.
e. Delayed main valve terminal is energized.
f.
Loss of flame signal.
g. Internal system fault occurred.
h. Purge card is removed.
i.
Purge card is bad.
6. RUN PERIOD
a. No flame present (JR2 removed).
b. Airflow lockout feature is enabled and the airflow
switch opens.
c. Interrupted pilot valve terminal is energized
(RM7897A, terminal 21; RM7897C, terminal 8).
d. Main valve terminal is not energized.
e. Delayed main valve terminal is not energized
(RM7897C).
f.
Internal system fault occurred.
g. Purge card is removed.
h. Purge card is bad.
i.
Ignition terminal is energized.
Safety Shutdown Sequence:
1. A safety shutdown occurring during Initiate or
Standby will lockout the RM7897 (prevent it from
starting) indicated by an alarm.
2. A safety shutdown occurring during purge results
the blower motor terminal 4 being de-energized and
the system will lockout indicated by an alarm.
3. A safety shutdown during the ignition trial period
(pilot or main) or Run, all fuel valves and the ignition
(if on) will be de-energized and the system will lock-
out indicated by an alarm. The RM7897 will com-
plete the programmed post purge before the blower
motor terminal 4 is de-energized. If no post purge is
programmed, the RM7897 will default to a 15 sec-
ond post purge.
Manual reset is required following any safety shutdown.
Manual reset may be accomplished by pressing the push
button on the device, pressing the remote reset wired
through an attached display or S7820 remote reset
module.
a
For RM7897C1026, if flame loss occurs during the first
15 seconds in the Run period, then lockout occurs. If
flame loss occurs after 15 seconds into the Run period,
then recycle.
13
a
32-00158—03
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