Sequence Of Operation - Honeywell 7800 SERIES Instruction Manual

EC7830A, RM7830A, EC7850A, RM7850A 7800 SERIES RELAY MODULES
d. Low Fire Switch fails to close within five minutes,
after firing rate motor is commanded to drive to low
fire position at end of purge (EC/RM7850A).
e. Airflow Switch Input does not close within 10
seconds.
f. If Airflow Switch is disabled, there is no jumper
between terminals 6 and 7.
g. Airflow Switch opens during PURGE.
h. Lockout Input opens during purge.
i. Ignition/pilot valve/intermittent pilot valve terminal is
energized.
j. Main valve terminal is energized.
k. Internal system fault.
l. Purge card is removed.
m. Purge card is defective.
4. PREIGNITION
a. Lockout Input opens during PREIGNITION.
b. Airflow Switch opens during PREIGNITION.
c. Preignition Interlock opens during PREIGNITION.
d. Flame signal detected during PREIGNITION.
e. Ignition terminal is not energized.
f. Pilot valve/intermittent pilot valve terminal is ener-
gized.
g. Main valve terminal is energized.
h. Internal system fault.
i. Purge card is removed.
j. Purge card is defective.
5. SAFETY 1 PERIOD
a. Lockout Input opens during SAFETY 1.
b. Airflow Switch opens during SAFETY 1.
c. Low Fire Switch opens (EC/RM7850A).
d. No flame is present at the end of SAFETY 1.
e. Ignition terminal is not energized.
f. Pilot valve/intermittent pilot valve terminal is not
energized.
g. Main valve terminal is energized.
h. Internal system fault.
i. Purge card is removed.
j. Purge card is defective.
6. PILOT STAB. PERIOD
a. Lockout Input opens during PILOT STAB.
b. Airflow Switch opens during PILOT STAB.
c. Low Fire Switch opens (EC/RM7850A).
d. No flame is present.
e. Ignition terminal is energized.
f. Pilot valve/intermittent pilot valve terminal is not
energized.
g. Main valve terminal is energized.
h. Internal system fault.
i. Purge card is removed.
j. Purge card is defective.
7. MAIN TRIAL PERIOD
a. Lockout Input opens during MAIN TRIAL.
b. irflow Switch opens during MAIN TRIAL.
c. Low Fire Switch opens (EC/RM7850A).
d. No flame is present.
e. Ignition terminal is energized.
f. Pilot valve/intermittent pilot valve terminal is not
energized.
g. Pilot valve is energized during MAIN TRIAL
stabilization.
h. Main valve terminal is not energized.
i. Internal system fault.
j. Purge card is removed.
k. Purge card is defective.
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8. RUN Period.
a. No flame is present.
b. Lockout Input opens.
c. Ignition/interrupted pilot valve terminal is energized.
d. Main valve terminal is not energized.
e. Internal system fault.
f. Purge card is removed.
g. urge card is defective.
h. Airflow Switch Input opens.
9. POSTPURGE Period.
a. Ignition/pilot valve/intermittent pilot valve terminal is
energized.
b. Main valve terminal is energized.
c. Internal system fault.
d. Purge card is removed.
e. Purge card is defective.
OPERATION

Sequence of Operation

The relay modules have the operating sequences listed
below; see Fig. 3 and 4. The relay module LED provide
positive visual indication of the program sequence: POWER,
PILOT, FLAME, MAIN and ALARM.
Initiate
The relay module enters the INITIATE sequence when the
relay module is initially powered. The relay module can also
enter the INITIATE sequence if the relay module verifies
voltage fluctuations of +10/-15% or frequency fluctuations of
±10% during any part of the operating sequence. The
INITIATE sequence lasts for two seconds unless the voltage
or frequency tolerances are not met. When not met, a hold
condition is initiated and displayed on the optional KDM for at
least five seconds; when met, the INITIATE sequence
restarts. If the condition is not corrected and the hold condition
exists for four minutes, the relay module locks out. Causes for
hold conditions in the INITIATE sequence:
a. Ac line dropout detection.
b. Ac line noise that can prevent a sufficient reading of
the line voltage inputs.
c. Low line voltage brownouts.
The INITIATE sequence also delays the burner motor starter
from being energized and de-energized from an intermittent
AC line input or control input.
Standby
The relay module 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 relay module to continue into the PURGE
sequence.
Normal Start-Up Purge
The relay module provides PURGE timing selectable from two
seconds to thirty minutes with power applied and the
operating control indicating a call for heat.
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