RM7895A RELAY MODULE
21
32-00122-01
a. Simulate a flame to cause the flame signal volt-
age level to be at least 1.25 Vdc for 40 seconds
after entry to STANDBY and also simulate a
flame signal for 30 seconds during PREPURGE.
b. Safety shutdown will occur.
3.
Failure to ignite pilot.
a. Close pilot and main fuel manual shutoff
valve(s).
b. Depress the reset push button.
c. Start the system.
d. Automatic pilot valve(s) should be energized but
the pilot cannot ignite.
e. Safety shutdown will occur.
4.
Failure to ignite main.
a. Open the manual pilot valve(s); leave the main
fuel manual shutoff valve(s) closed.
b. Depress the reset push button.
c. Start the system.
d. Pilot should ignite and the flame signal should
be at least 1.25 Vdc but the main burner cannot
light.
e. Close the manual pilot valve(s).
f.
Flame signal should drop below 1.25 Vdc within
three seconds after pilot goes out.
g. Safety shutdown will occur.
5.
Loss of flame during RUN.
a. Open the main fuel manual shutoff valve(s). The
manual pilot shutoff valve(s) must also be
opened.
b. Depress the reset push button.
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 fir-
ing, close the manual main and pilot fuel shutoff
valves to extinguish the main burner flame.
e. The flame signal should drop below 1.25 Vdc
within three seconds after the main flame goes
out.
f.
Safety shutdown will occur.
IMPORTANT
1. If the RM7895 fails to shut down on any of these
tests, take corrective action (refer to
Troubleshooting, RM7895 diagnostics and return
to the beginning of all Checkout tests).
2. When all Checkout tests have been completed,
reset all switches to original states.
TROUBLESHOOTING
RM7895 Diagnostics
Troubleshooting control system equipment failures is
easier with the RM7895 self-diagnostics and first-out
annunciation. In addition to an isolated spst alarm relay
(audible annunciation), the RM7895 provides visual
annunciation by displaying the ALARM LED.
Self-diagnostics of the RM7895 enables it to detect and
annunciate both external and internal system problems.
External faults such as interlock failures, flame failures
and false flame signals are annunciated by the RM7895,
which energizes the ALARM LED or by using the optional
Keyboard Display Module. The 7800 SERIES provides a
System Annunciation Diagnostics and Troubleshooting
manual, form 65-0233.
The RM7895 provides diagnostic information to aid the
service mechanic to obtain information when
troubleshooting the system, see Table 8.
The optional Keyboard Display Module displays sequence
status messages indicating: STANDBY, PREPURGE, PILOT
IGN, MAIN 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 RM7895 with the optional Keyboard Display Module
can monitor input/output terminals and can display the
status of the terminal on the KDM. Example: Pilot Valve 1,
see S7800A1019 Keyboard Display Module
Specifications. A complete terminal description and
number are provided. The display will show the actual
status of the terminal. If voltage is detected at the
terminal, 1 is displayed; but if no voltage is detected at the
terminal, 0 is displayed.
Historical Information Index
The RM7895 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 S7800
Keyboard Display Module.
SERVICE NOTE: A Lockout condition or restart of an
RM7895 can be accomplished by pressing the reset
push button on the RM7895, or by pressing a remote
reset push button 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 RM7895 but
will not reset a lockout condition.
SERVICE NOTE: Remove the access slot covers on the
side of the Q7800A to check voltages.
WARNING
Electrical Shock Hazard.
Can cause serious injury or death.
Line voltage is present on some of the wiring
subbase terminals. Reinstall the access slot covers
after performing voltage checks to prevent
electrical shock.
NOTE:
In Table 8, normal sequences are in bold type,
while abnormal sequences are in regular type.
