Product Overview

RM7890; RM7895 100 VAC 7800 SERIES RELAY MODULES
13 66-1195—01
c. KDM: The KDM is powered from a low voltage,
energy-limited source, so it can be mounted outside
of the control panel if it is protected from mechanical
damage.
NOTE: Use a separate 13 Vdc power supply any time
more than two Data ControlBus™ Modules or
KDM are used or when placed more than 100 feet
(30 meters) from the relay module.
d. Remote Reset Module:
(1) Do not run high voltage ignition transformer
wires in the same conduit with the Remote Reset
Module wiring.
(2) Do not route Remote Reset Module wires in
conduit with line voltage circuits.
8. Maximum wire lengths:
a. For the relay module, the maximum length of
leadwire to the control terminal input is 300 feet (91
meters).
b. For the flame detector leadwires, the maximum
flame sensor leadwire length is limited by the flame
signal strength.
c. Remote Reset Module leadwires: The maximum
length of wire is 1000 feet (305 meters) to a Remote
Reset Module pushbutton.
d. Data ControlBus™ or Modbus™ Module: The maxi-
mum cable length depends on the number of sys-
tem modules connected, the noise conditions, and
the cable used. The maximum length of all intercon-
necting wires is 1000 feet (305 meters).
9. Make sure loads do not exceed the terminal ratings.
Refer to the label on the relay module or to the ratings in
the Specifications section. See Table 1.
10. Check the power supply circuit to be sure the voltage
and frequency tolerance match those of the relay
module. A separate power supply circuit can be
required for the relay module with the required
disconnect means and overload protection added.
11. Check all wiring circuits and complete the Static
Checkout, see Table 8, before installing the relay
module on the wiring subbase.
12. Install all electrical connectors.
13. Restore power to the panel.
ASSEMBLY
Mounting RM7890; RM7895
NOTE: For installation dimensions, see Fig. 1 or 2.
Relay Module Mounting
1. Mount the relay module vertically, see Fig. 7 or 8, or
mount horizontally with the knife blade terminals
pointing downward. When mounting on the Q7800A
Wiring Subbase, the relay module must be in an
electrical enclosure.
2. Select the location in the electrical enclosure. Be sure to
allow adequate clearance for servicing, installation and
removal of the relay module, dust cover, flame amplifier,
flame amplifier signal voltage probes, electrical signal
voltage probes and electrical connections.
a. Allow an additional two inches (51 mm) below the
relay module for the flame amplifier mounting.
b. Allow an optional three-inch (76 mm) minimum to
both sides of the relay module for electrical signal
voltage probes.
3. Make sure subbase wiring does not project beyond the
terminal blocks. Tuck in wiring against the back of the
subbase so it does not interfere with the knife blade
terminals or bifurcated contacts.
IMPORTANT
The relay module must be installed with a plug-in
motion rather than a hinge action.
4. Mount the relay module by aligning the four L-shaped
corner guides and knife blade terminals with the
bifurcated contacts on the wiring subbase and securely
tightening the two screws without deforming the plastic.
Dust Cover Mounting
1. Align the interlocking ears of the dust cover with the two
mating slots in the relay module, see Fig. 9.
2. Insert the two interlocking ears into the two mating slots,
and with a hinge action, push on the upper corners of
the dust cover to secure it to the relay module.
3. Be sure the dust cover is firmly in place.
Installing ST7800 Purge Card
(RM7895 Only)
1. Remove the dust cover, KDM, Data ControlBus™
Module, or extension cable assembly.
2. Remove the current ST7800 Purge Card from the relay
module by pulling upward on the plastic support cover.
See Fig. 10.
3. Make sure that the ST7800 Purge Card selected has
the desired purge timing.
4. Insert the ST7800 Purge Card into the opening of the
relay module purge card compartment. See Fig. 10.
Installing Plug-In Flame Signal
Amplifier
1. Disconnect the power supply before beginning
installation to prevent electrical shock and equipment
damage. More than one disconnect can be involved.
2. Align the amplifier circuit board edge connector with the
keyed receptacle on the relay module. Verify that the
amplifier nameplate faces away from the relay module.
See Fig. 11.
3. Push in the amplifier until the circuit board is fully
inserted into the receptacle and then push the amplifier
toward the relay module retaining clasp.
4. Verify the amplifier is firmly in place.
5. Perform all required checkout tests.
Installing Flame Detector
NOTE: See Table 4 for the flame detection system
available for use with the relay module. Make
sure the correct combination of amplifier and
flame detector is used.