28
RM7895A,B,C,D
CHECKOUT • TROUBLESHOOTING
FLAME SIGNAL WITH HOT COMBUSTION
CHAMBER (All Installations)
After all initial start-up tests and burner adjustments are
completed, operate the burner until the combustion cham-
ber is at the maximum expected temperature. Observe the
equipment manufacturer warmup instructions. Recycle the
burner under these hot conditions and measure the flame
signal. Check the pilot alone, the main burner flame alone,
and both together (unless monitoring only the pilot flame
when using an intermittent pilot, or only the main burner
flame when using DSI).
Check the FFRT of the Flame Amplifier. Lower the set
point of the operating controller and observe the time it
takes for the burner flame to go out. This should be within
.8 or 3 seconds maximum depending on the amplifier
selected.
If the flame signal is too low or unsteady, check the flame
detector temperature. Relocate the detector if the tempera-
ture is too high. If necessary, realign the sighting to obtain
the proper signal and response time. If the response time is
still too slow, replace the Plug-in Flame Signal Amplifier.
If the detector is relocated or resighted, or the amplifier is
replaced, repeat all required Checkout tests.
SAFETY SHUTDOWN TESTS (All Installations)
Perform these tests at the end of Checkout after all other
tests have been completed. If used, the external alarm
should turn on. Press the RM7895 reset pushbutton to restart
the system.
1. Close the Airflow interlock during STANDBY for 120
seconds, (RM7895B,D).
2. Close the Airflow Interlock during PREPURGE, PI-
LOT IGN, MAIN IGN or RUN period.
a. Safety shutdown will occur if the Airflow ILK
Switch Failure configuration jumper (JR3) is
clipped.
3. Detect flame 40 seconds after entry to STANDBY.
Detect flame 30 seconds during measured PREPURGE time.
a. Simulate a flame to cause the flame signal voltage
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.
4. Failure to ignite pilot.
a. Close the 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.
5. 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
.8 or 3 seconds (depending on the FFRT of the
amplifier) after the pilot goes out.
g. Safety shutdown will occur.
6. 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 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 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 SYSTEM DIAGNOSTICS
Troubleshooting control system equipment failures is
easier with the RM7895 self-diagnostics and first-out annun-
ciation. 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 enable it to detect and
annunciate both external and internal system problems. Ex-
ternal faults such as interlock failures, flame failures and false
flame signals are annunciated by the RM7895, which ener-
gizes the ALARM LED or by using the optional Keyboard
Display Module. The 7800 SERIES provides a System An-
nunciation Diagnostics and Troubleshooting manual, form
65-0118.
The RM7895 provides diagnostic information to aid the
service mechanic to obtain information when troubleshoot-
ing the system, see Table 6.
The optional Keyboard Display Module displays se-
quence status messages indicating: STANDBY, PRE-PURGE,
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,
