Honeywell 7800 Series Manual page 8

CR7890B 7800 SERIES INTEGRATED BURNER CONTROL
Terminal Number
7
5
9
3
6
1
8
2
4
a
Numbers refer to pin numbers on Brad Harrison® 3R9006A20A120 Connector.
The CR7890 must have an earth ground providing a connection between the device and the control panel or the equipment.
b
The earth ground wire must be capable of conducting the current to blow the 15A fast-blow fuse (or breaker) in event of an
internal short circuit. The CR7890 needs a low impedance ground connection to the equipment frame which, in turn, needs a
low impedance connection to earth ground. For a ground path to be low impedance at RF frequencies, the connection must be
made with min-imum length conductors having maximum surface areas. Wide straps or brackets rather than leadwires are
preferred. Be careful to verify that mechanically tightened joints along the ground path, such as pipe or conduit threads or
surfaces held together with fasteners, are free of nonconductive coatings and are protected against mating surface corrosion.
2000 VA maximum connected load to the CR7890 Assembly.
c
See Tables 4 and 5 for device load combinations.
d
EARTH
GROUND
9
1
RESET
PUSH-
BUTTON
STATUS LEDs
LIMITS CONTROLLER
3K1
OPTIONAL KEYBOARD
DISPLAY MODULE
DDL
65-0259—1
Table 3. Terminal Ratings.
a
Earth Ground
Line Voltage Common
Line Voltage Supply (L1)
Alarm
Reset
Burner Controller and Limits
Pilot Valve/Ignition
Main Fuel Valve
Ignition
L1
7
L2
(HOT)
2
FLAME
SIGNAL
6
MICROCOMPUTER
RELAY
2K
DRIVE
CIRCUIT 3K
4K
SAFETY RELAY
1K
CIRCUIT
POWER SUPPLY
1K1
1
2K1
3
INDICATES FEEDBACK SENSING
TO RELAY STATUS FEEDBACK
AND LINE VOLT INPUTS
Fig. 6. Internal block diagram of the CR7890.
Description
b
FLAME
DETECTOR
VOLTAGE TO
CURRENT (-)
TEST
ASIC
JACKS
TEST
4
RELAY
STATUS
FEEDBACK
AND LINE
VOLTAGE
INPUTS
CONTROL
POWER
2K2 5K1
IGNITION
4
4K1
8 PILOT
2 MAIN VALVE
3
ALARM
8
Ratings
—
—
120 Vac (+10%/-15%), 50 or 60 Hz
c
(±10%).
120 Vac, 1A pilot duty.
120 Vac, 10 mA maximum.
120 Vac, 8A run, 43A inrush.
d
120 Vac.
d
120 Vac.
120 Vac, 4.5A ignition.
5
1 NUMBERS IN CIRCLES ARE CR7890B1019
CONNECTOR NUMBERS.
2
PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
120 VAC, 50/60 HZ.
3 KEYBOARD DISPLAY MODULE USED FOR
DIAGNOSTICS ONLY.
4 ASIC = APPLICATION SPECIFIC INTEGRATED
CIRCUIT.
FIELD WIRING
INTERNAL WIRING
d
M17914D