CB780/CB784 RELAY MODULES
32-00207—01 8
Verified Spark Termination
The ignition terminal is monitored to verify early spark
termination (five seconds ignition and pilot and five
seconds pilot only).
First-Out Annunciation and Self-
Diagnostics
Sequence Status Lights (LEDs) provide positive visual
indication of the program sequence: POWER, PILOT,
FLAME, MAIN and ALARM. The green POWER LED blinks
every four seconds to signify the CB780/CB784 hardware
is running correctly.
Multi-function Keyboard Display Module (standard with
CB780, optional with CB784) shows elapsed time during
PREPURGE, PILOT IGN, MAIN IGN, and POSTPURGE. As
an additional troubleshooting aid, it provides sequence
timing, diagnostic information, historical information and
expanded annunciator information when a safety
shutdown or hold or normal operation occurs.
First-out Annunciation reports the cause of a safety
shutdown or identifies the cause of a failure to start or
continue the burner control sequence with an English text
and numbered code via the Keyboard Display Module. It
monitors all field input circuits, including the Flame
Signal Amplifier and Firing Rate Position Switches. The
system distinguishes 118 modes of failure and detects
and annunciates difficult-to-find intermittent failures.
Self-Diagnostics adds to the First-out Annunciation by
allowing the CB780/CB784 to distinguish between field
(external device) and internal (system related) problems.
Faults associated within the flame detection subsystem,
CB780/CB784 or plug-in Purge Card, are isolated and
reported by the Keyboard Display Module, see
Troubleshooting section and CB780/CB784 System
Annunciation Diagnostics and Troubleshooting, Bulletin
Number CB-7803.
Interlock Requirements
The following interlock inputs are provided:
Low Fire Interlock
This interlock verifies the firing rate motor is in the low fire
position before and during ignition trials.
High Fire Interlock
This interlock verifies the firing rate motor is in the high
fire position prior to and during PREPURGE.
Lockout Interlock
This interlock (ILK) input signifies a Lockout Interlock. If
the Lockout Interlock is open for more than ten seconds
into PREPURGE, the CB780/CB784 will lockout. After
entering PREPURGE, if the Lockout Interlock opens
during the first ten seconds, the purge timer will be reset.
This provides a continuous PURGE to occur without
interruption before the Pilot Flame Establishing Period. If
a Lockout Interlock opens anytime after ten seconds into
PURGE, during the Ignition Trials or Run, it causes a
lockout.
A typical Lockout Interlock string contains an airflow
switch (see Fig. 7). The Interlock Check is a site
configurable option (see Table 7). If this feature is enabled,
the CB780/CB784 will lockout after 120 seconds
whenever control terminal 6 is energized, and the Lockout
Interlock string (including airflow switch) is closed during
STANDBY.
Preignition Interlock
The Preignition Interlock input is typically connected to
proof-of-closure switches for fuel valve(s). The Preignition
Interlock must be energized throughout PREPURGE. If the
Preignition Interlock opens during STANDBY, it causes a
hold (30 seconds). The CB780/CB784 will lockout if the
interlock does not close within 30 seconds during
STANDBY. If the Preignition Interlock opens during
PREPURGE, it will lockout. If the Preignition Interlock is
open after five seconds into POSTPURGE, the
CB780/CB784 will lockout. The Preignition Interlock is
ignored during the ignition trials state and during RUN.
INSTALLATION
Fire or Explosion Hazard.
Can cause severe injury, death or property
damage.
To prevent possible hazardous burner operation,
verification of safety requirements must be
performed each time a control is installed on a
burner.
When Installing This Product…
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazard-
ous
condition.
2. Check the ratings given in the instructions and
marked on the product to make sure the product is
suitable for the application.
3. Installer must be a trained, experienced, flame safe-
guard technician.
4. After installation is complete, check out the product
operation as provided in these instructions.
Electrical Shock Hazard.
Can cause severe injury, death or property
damage.
Disconnect the power supply before beginning
installation to prevent electrical shock, equipment
and control damage. More than one power supply
disconnect may be involved.
Wiring Information
1. Wiring connections for the CB780/CB784 are
unique; therefore, refer to Figs. 6, 7, 8 or 9 or the cor-
rect Specifications for proper subbase wiring.
2. Wiring must comply with all applicable codes, ordi-
nances and regulations.
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