CB780/CB784 RELAY MODULES
32-00207—01
6
Fig. 5. Infrared detector, mounting dimensions
in inches (mm).
PRINCIPAL TECHNICAL
FEATURES
The CB780/CB784 provides all customary flame
safeguard 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 240 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 ter-
minal 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 PRE-
PURGE.
b. Flame signal detected after first ten seconds
during PREPURGE.
c. High Fire Switch fails to close within four min-
utes, 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 com-
manded to drive to low fire position at end of
PREPURGE.
e. Lockout Interlock does not close within 10 sec-
onds.
f.
Lockout Interlock opens during PREPURGE.
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 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 ter-
minal is not energized.
d. Early Spark Termination terminal is energized
after 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 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.
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
seconds or opens after five-second time period.
b. Ignition/pilot valve/intermittent pilot valve ter-
minal is energized.
c. Main valve terminal is energized.
d. Internal system fault.
e. Purge card is removed.
f.
Purge card is bad.
SAFETY PROVISIONS
Internal Hardware Status
Monitoring
The CB780/CB784 checks the purge card for correct
parity to prevent purge timing shifts and circuitry failures.
It also analyzes the integrity of the configuration jumpers
and internal hardware. The POWER LED blinks every four
seconds, signifying an internal hardware check.
Closed Loop Logic Test
The test verifies the integrity of all safety critical loads,
terminals 8, 9, 10 and 21. If the loads are not energized
properly; i.e., the main valve terminal is powered during
PREPURGE, the CB780/CB784 will lockout on safety
shutdown. The CB780/CB784 must react to input
APERTURE
BUSHING WITH
MAGNIFYING LENS
COLLAR, 3/4-14 NPSM
INTERNAL THREADS
3/4-14
NPSM
3/4-14 NPSM
INTERNAL
THREADS
HEAT BLOCK
CELL MOUNT
M27237A
2 LEADS IN A
48 INCH (1.2 METER)
FLEXIBLE CONDUIT
2-3/4*
(70)
1-1/4
(32)
1-5/8 (41)
1-1/16 (27)
1-1/4
(32)
817-1742 OR 817-4133
*
817-4133 IS 2-1/4 (58) TOTAL LENGTH