1-6 750-166
CB780/CB784
PRINCIPAL TECHNICAL FEATURES
Principal Technical Features
The CB780/CB784 provides all customary flame safe-
guard functions while providing significant advancements in
the areas of 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).
d. AC line power errors, see Operation.
e. Four minute INITIATE period is exceeded.
2. STANDBY Period
a. Flame signal is present after 40 seconds.
b. Preignition Interlock is open an accumulative time
of 30 seconds.
c. Interlock check feature is enabled and the Inter-
lock String (including the airflow switch) is closed
for 120 seconds with controller closed.
d. Ignition/pilot valve/intermittent pilot valve termi-
nal is energized.
e. Main valve terminal is energized.
f. Internal system fault.
g. Purge card is not installed or removed.
h. Purge card is bad.
3. PREPURGE Period
a. Preignition Interlock opens anytime during
PREPURGE.
b. Flame signal detected after first ten seconds during
PREPURGE.
c. High Fire Switch fails to close within four minutes,
fifteen seconds after firing rate motor is commanded
to drive to high fire position at start of PREPURGE.
d. Low Fire Switch fails to close within four minutes,
fifteen seconds after firing rate motor is commanded
to drive to low fire position at end of PREPURGE.
e. Lockout Interlock does not close within 10 seconds.
f. Lockout Interlock opens during PREPURGE.
g. Ignition/pilot valve/intermittent pilot valve termi-
nal is energized.
h. Main valve terminal is energized.
i. Internal system fault.
j. Purge card is removed.
k. Purge card is bad.
4. PILOT FLAME ESTABLISHING Period (PFEP)
a. Low Fire Switch opens.
b. Lockout Interlock opens.
c. Ignition/pilot valve/intermittent pilot valve terminal
is not energized.
d. Early Spark Termination terminal is energized af-
ter five seconds.
e. No flame is present at end of PFEP.
f. Internal system fault.
g. Purge card is removed.
h. Purge card is bad.
5. MAIN FLAME ESTABLISHING Period (MFEP)
a. Low Fire Switch opens.
b. Lockout Interlock opens.
c. Ignition/pilot valve/intermittent pilot valve termi-
nal 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.
6. RUN Period
a. No flame is present.
b. Lockout Interlock opens.
c. Main valve terminal is not energized.
d. Internal system fault.
e. Purge card is not installed or removed.
f. Purge card is bad.
7. POSTPURGE Period
a. Preignition Interlock does not close within five sec-
onds or opens after five-second time period.
b. Ignition/pilot valve/intermittent pilot valve termi-
nal is energized.
c. Main valve terminal is energized.
d. Internal system fault.
e. Purge card is removed.
f. Purge card is bad.
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