Principal Technical Features; Sequence Of Operation - Honeywell 7800 Series Installation Instructions Manual

PRINCIPAL TECHNICAL
FEATURES
The RM7838B,C 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 were changed after
200 hours of operation.
d. AC line power errors, see Operation.
e. Four minute INITIATE period is exceeded.
2. STANDBY Period
a. Flame signal is present after 240 seconds after
Run Complete.
b. Preignition Interlock is open after 30 seconds.
c. Ignition/pilot valve terminal is energized.
d. Main valve terminal is energized.
e. Internal system fault.
f. Purge card is not installed or removed.
g. Purge card is bad.
h. Flame detected during the last two seconds.
3. PURGE Period
a. Preignition Interlock opens anytime during
purge.
b. Flame signal detected during purge .
c. High Purge Rate Switch fails to close within four
minutes, fifteen seconds after the firing rate
motor is commanded to drive to high fire posi-
tion.
d. Low Fire Start Switch fails to close within four
min-utes, fifteen seconds after the firing rate
motor is commanded to drive to low fire position.
e. Lockout Interlock does not close within five sec-
onds.
f. Lockout Interlock opens during purge .
g. Ignition/pilot valve/intermittent pilot valve ter-
minal is energized.
h. Main valve terminal is energized.
i. Internal system fault.
j. Purge card is not installed or removed.
k. Purge card is bad.
4. Purge Hold: T21
a. Preignition Interlock opens.
b. Flame is detected.
c. Lockout Interlock opens during Hold.
d. Ignition/pilot valve/main valve is energized.
e. Internal system fault.
f. Purge card is removed.
g. Purge card is bad.
5. PILOT FLAME ESTABLISHING Period (PFEP)
a. Low Fire Switch opens.
b. Lockout Interlock opens .
c. Ignition/pilot valve/intermittent pilot valve ter-
minal is not energized.
d. No flame is present at end of PFEP.
e. Internal system fault.
RM7838B,C 7800 SERIES RELAY MODULE
f. Purge card is not installed or removed.
g. Purge card is bad.
6. MAIN FLAME ESTABLISHING Period (MFEP)
a. Low Fire Switch opens.
b. Lockout Interlock opens .
c. Ignition/pilot valve/intermittent pilot valve ter-
minal is not energized.
d. Main valve terminal is not energized.
e. No flame is present at end of MFEP.
f. Internal system fault.
g. Purge card is not installed or removed.
h. Purge card is bad.
7. RUN Period
a. Flame is present.
b. Lockout Interlock opens.
c. Main valve terminal is de-energized.
d. Internal system fault.
e. Purge card is not installed or removed.
f. Purge card is bad.
8. Pilot Valve Hold
a. Low Fire Switch opens.
b. Lockout Interlock opens.
c. Ignition/pilot valve terminal is not energized.
d. No flame is present at end of PFEP.
e. Internal system fault.
f. Purge card is not installed or removed.
g. Purge card is bad.
h. Non Shutter Check Amplifier/Detector used.
OPERATION

Sequence of Operation

The RM7838B,C has the operating sequences listed
below. The RM7838B,C LED provide positive visual
indication of the program sequence: POWER, PILOT,
FLAME, MAIN and ALARM. Fig. 6 and 7 show the
operating sequences not using pilot valve hold and using
pilot valve hold, respectively.
Initiate
The RM7838B,C enters the INITIATE sequence when the
Relay Module is initially powered. The RM7838B,C can
also enter the INITIATE sequence if the Relay Module
verifies voltage fluctuations of +10/-15 percent or
frequency fluctuations of ±10 percent during any part of
the operating sequence. The INITIATE sequence lasts for
ten seconds unless the voltage or frequency tolerances
are not met. When the tolerances are not met, a hold
condition is initiated and displayed on the KDM for at least
five seconds. When the tolerances are met, the INITIATE
sequence restarts. If the condition is not corrected and the
hold condition exists for four minutes, the RM7838B,C
locks out. Causes for hold conditions in the INITIATE
sequence:
a. ac line dropout detection.
b. ac line noise that prevents a sufficient reading of
the line voltage inputs.
c. Low line voltage brownouts.
The Alarm, terminal 3, is energized during INITIATE
(RM7838B only).
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