7800 SERIES EC7885A/RM7885A RELAY MODULE
65-0203
22
See Fig. 18 for location of component parts and see Fig. 7 or
Q7800 Specification for terminal locations.
Preliminary Inspection
Perform the following inspections to avoid common problems.
Be sure:
A
Wiring connections are correct and all terminal screws
are tight.
B
Flame detector(s) is clean, installed and positioned
properly. Consult the applicable Instructions.
C
Correct combination of amplifier and flame detector(s)
is used, (see Table 2).
D
Plug-in amplifier is securely in place.
E
Burner is completely installed and ready to fire; consult
equipment manufacturer instructions. Fuel lines are
purged of air.
F
Combustion chamber and flues are clear of fuel and
fuel vapor.
G
Power is connected to the system disconnect switch
(master switch).
H
Lockout switch is reset (push in reset pushbutton) only
if the 7885A is powered, see Fig. 1 and 2.
I
System is in the STANDBY condition. POWER LED is
energized.
J
All limits and interlocks are reset.
NEGATIVE (-)
METER LEAD
POSITIVE (+)
METER LEAD
ONE
MEGOHM/VOLT
METER
M7383
Fig. 19. Flame signal measurement.
Flame Signal Measurement (Fig. 19)
Table 5. Flame signal.
Measure the flame signal at the appropriate times defined in
the following Checkout Tests. Read the flame signal volts dc
at the flame amplifier test jacks + and - (Com).
1. Use a 1M ohm/volt meter with a 0 to 10 Vdc capability.
2. Set the 1M ohm/volt meter to the 0 to 10 Vdc range.
3. Insert the positive (red) probe into the + jack of the
flame amplifier. Insert the negative (black) probe into
the - (Com) jack of the flame amplifier.
4. Allow a few seconds for the meter reading to stabilize.
5. When using AMPLI-CHECK® or shutter check
amplifiers, you should read the average stable voltage,
disregarding the highs and lows caused by the self-
checking operation.
6. The meter reading must be as specified in Table 5 after
all tests are completed and all adjustments are made.
As an option, the flame signal can be checked by using the
optional Keyboard Display Module.
If the signal is unstable or less than the minimum acceptable
voltage, check the flame detector installation and circuitry.
1. Check the supply voltages at terminals 3 (L1) and L2
(N). Make sure the master switch is closed,
connections are correct, and the power supply is of the
correct voltage and frequency and is sinusoidal.
2. Check the detector wiring for defects including:
•
Incorrect connections.
•
Wrong type of wire.
•
Deteriorated wire.
•
Open circuits.
•
Short circuits.
•
Leakage paths caused by moisture, soot or
accumulated dirt.
Acceptable Flame Detector
Maximum Flame Signal Amplifier
Steady dc Voltage
a
Expected Dc Voltage
Flame Rod Photocell
R7847A,B
b
1.25 Vdc
5.0 Vdc at the Keyboard
Display Module
C7012A,C
or
C7012E,F
R7847C
c
5.0 Vdc at a Volt
C7015A
R7848A,B
b
ohmmeter
C7027A
R7849A,B
b
C7035A
C7044A
C7061
R7861
C7076A,D
R7886A
a
This minimum or a stronger signal should be easily obtained if the detector is correctly installed and positioned to properly
sense the flame. This voltage must be obtained before completing checkout.
b
The flame amplifiers are AMPLI-CHECK® type.
c
The flame signal amplifier circuitry is tested one-half second every five seconds during burner operation and shuts down
the burner if the amplifier fails (all installations).
