7800 SERIES EC7885A/RM7885A RELAY MODULE
65-0203
28
2. Failure to ignite pilot.
a.
Close the pilot and main fuel manual shutoff
valve(s).
b.
Press the Start Switch.
c.
Automatic pilot valve(s) and the spark should be
energized but the pilot cannot ignite.
d.
Shutdown will occur after 15 minutes.
3. Loss of flame during RUN.
a.
Open the pilot and main fuel manual shutoff
valve(s).
b.
Start the system. Start-up should be normal and
the main burner should light normally.
c.
After the sequence is in the normal RUN period
for at least ten seconds with the main burner
firing, close the manual main and pilot fuel shutoff
valve(s) to extinguish the flame.
d.
The flame signal should drop below 1.25 Vdc
within .8 or 3 seconds (depending on the FFRT of
the amplifier) after the flame goes out.
e.
The 7885 returns to STANDBY and the alarm
sounds.
IMPORTANT
1.
If the 7885A fails to shutdown on any of these tests,
take corrective action (refer to Troubleshooting,
7885A Diagnostics, and return to the beginning of all
Checkout Tests).
2.
When all Checkout Tests are complete, reset all
switches to original states.
TROUBLESHOOTING
7885A System Diagnostics
Troubleshooting control system equipment failures is easier
with the 7885A self-diagnostics and first-out annunciation. It
provides an isolated spst alarm relay (audible annunciation)
and also provides visual annunciation by displaying the status
LEDs.
Self-diagnostics of the 7885A enable it to detect and
annunciate both external and internal system problems.
External faults such as flame failures and false flame signals
are annunciated by the 7885A alarm output and energizing
the ALARM LED, or by using the optional Keyboard Display
Module.
The 7885A provides diagnostic information to aid the service
mechanic to obtain information when troubleshooting the
system, see Table 6.
The optional Keyboard Display Module displays sequence
status messages indicating: STANDBY, PILOT IGN and RUN.
The selectable messages also provide visual indication,
current status and historical status of the equipment such as:
Flame Signal, Total Cycles, Total Hours, Fault History,
Diagnostic Information and Expanded Annunciator Terminal
Status (if used). With this information, most problems can be
diagnosed without extensive trial and error testing.
Information available in the Diagnostic Information file
includes: Device Type, Device Suffix, Software Revision,
Manufacturing Code, Flame Amplifier Type, Flame Failure
Response Time, Selectable Jumper Configuration Status and
Terminal Status.
Diagnostic Information Index
The 7885A with the optional Keyboard Display Module can
monitor input-output terminals and can display the status of
the terminal at the VFD (Pilot Valve T8 ON<), see S7800A
Keyboard Display Module Specification. A complete terminal
description and terminal number is provided. The display
shows the actual status of the terminal. If voltage is detected
at the terminal, ON is displayed; but if no voltage is detected
at the terminal, OFF is displayed.
Historical Information Index
The 7885A has nonvolatile memory that allows the Relay
Module to retain historical information for the six most recent
faults. Each of the six lockout files retains the cycle when the
fault occurred, the hour of operation when the fault occurred,
and the fault message and burner status when the fault
occurred. The Historical Information can be viewed by the
optional S7800A Keyboard Display Module.
SERVICE NOTE:
A Lockout condition or restart of an 7885A
can be accomplished by pressing the
reset pushbutton on the 7885A, or by
pressing a remote reset pushbutton wired
through an optional Keyboard Display
Module, DATA CONTROLBUS
MODULE™ or Remote Reset Module. A
power-up reset causes an electrical reset
of the RM7885A but does not reset a
lockout condition.
SERVICE NOTE:
Remove the access slot covers on the
sides of the Q7800A,B to check voltages.
CAUTION
To avoid electrical shock or equipment damage,
reinstall access slot covers on the Q7800A,B Subbase
after performing voltage checks.
SERVICE NOTE:
Maximum ambient operating temperature
of a C7012E,F Series 1 through 6 is
reduced to 125
°
F because of the duty
cycle operation of the 7885A Relay
Module.
