Troubleshooting - Honeywell 7800 Series Manual

Relay module

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Product data (64 pages)

Manual (56 pages)

Installation instructions manual (40 pages)

Table of Contents

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.

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

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.