7800 SERIES EC7890A,B/RM7890A,B RELAY MODULE
65-0204–1
26
2
Failure to ignite pilot.
a.
Close the pilot and main fuel manual shutoff
valve(s).
b.
Depress the reset pushbutton.
c.
Start the system.
d.
Automatic pilot valve(s) should be energized but
the pilot cannot ignite.
e.
Safety shutdown will occur.
3
Loss of flame during RUN (if Flame Failure Action
configuration jumper, JR2, is selected for Lockout).
a.
Open the main fuel manual shutoff valve(s). The
manual pilot shutoff valve(s) must also be
opened.
b.
Depress the reset pushbutton.
c.
Start the system. Startup should be normal and
the main burner should light normally.
d.
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 main burner flame.
e.
The flame signal should drop below 1.25 Vdc
within .8 or 3 seconds (depending on the FFRT of
the amplifier) after the main flame goes out.
f.
Safety shutdown will occur.
IMPORTANT
1.
If the 7890 fails to shut down on any of these
tests, take corrective action (refer to
Troubleshooting section, 7890 Diagnostics
subsection and return to the beginning of all
Checkout tests).
2.
When all Checkout tests are complete, reset all
switches to original states.
TROUBLESHOOTING
7890 System Diagnostics
Troubleshooting control system equipment failures is easier
with the 7890 self-diagnostics and first-out annunciation. In
addition to an isolated spst alarm relay (audible
annunciation), the 7890 provides visual annunciation by
displaying the ALARM LED.
Self-diagnostics of the 7890 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 a lockout of the 7890 that energizes the
ALARM LED by using the optional Keyboard Display Module
or 7800 SERIES System Annunciation Diagnostics and
Troubleshooting, form 65-0118.
The 7890 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: INITIATE, STANDBY, SAFE-
START CHECK, 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 7890 with the optional Keyboard Display Module can
monitor input/output terminals and can display the status of
the terminal at the VFD (eg, Pilot Valve T8 ON<); see S7800A
Keyboard Display Module Specifications. A complete terminal
description and terminal number are provided. The display
will show the actual status of the terminal. If voltage is
detected at the terminal, ON is displayed; but if voltage is not
present at the terminal, OFF is displayed.
Historical Information Index
The 7890 has nonvolatile memory that allows the Relay
Module to retain Historical Information for the six most recent
lockouts. 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 restart of an 7890 can be
accomplished by pressing the reset
pushbutton on the 7890, or by pressing
a remote reset pushbutton wired through
an optional Keyboard Display Module,
DATA CONTROLBUS MODULE™,
Extension Cable Assembly, or Remote
Reset Module. A power-up reset will
cause an electrical reset of the 7890 but
will not reset a lockout condition.
SERVICE NOTE:
To check voltages, remove the access
slot covers on the sides of the
Q7800A,B.
CAUTION
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 will be reduced to 125
°
F
because of the duty cycle operation of
the RM7890B Relay Module.
