BCU 460, BCU 465 · Edition 11.19
28
Function
3 .2 .8 Assignment of connection terminals
Terminal Type
Designation
Function
1
Control input
(AC mains voltage)
Start-up signal
Signal applied: heating start; no signal: heating stop
2
Remote reset
Input for external signal (button) to reset the unit after a fault lock-out. System faults
(internal errors) can only be acknowledged using this button.
3
External purge air
If there is an active signal, the BCU opens the air actuator regardless of the status of the
other inputs.
4
External air valve control
External air valve control with an active signal, e.g. to supply air to the combustion chamber
for cooling. Controlled air flow is only possible in standby with deactivated start-up signal.
As soon as heating operation is started (start-up signal at terminal 1), the function is
interrupted.
6
High temperature operation
feedback
High temperature operation feedback input. When the input is activated, the BCU operates
without evaluating the flame signal. The safety function of the device’s internal flame
control system is deactivated.
7
Flameless operation (Low NO
x
mode) feedback
Low NO
x
mode feedback input. When the input is activated, the BCU operates without
evaluating the flame signal. The safety function of the device’s internal flame control
system is deactivated. The furnace chamber temperature is monitored by a safety
temperature monitor (STM).
35
Controller enable/Emergency
stop
Connection for higher-level safety devices and interlocks (e.g. emergency stop)
39
LDS query
Feedback signal of the control element position for ignition capacity. As soon as a signal is
present, the BCU completes a burner start, restart or start-up attempt.
40
Safety circuit input
(AC mains voltage)
Feedback from actuator
Feedback input for ignition position
41
Feedback from actuator
Feedback input for maximum capacity
22
Input (
�
A)
Flame signal 1 (pilot burner)
Connection for flame rod/UV sensor/ignition transformer
23
Flame signal 2 (main burner)
Connection for flame rod/UV sensor/ignition transformer
52, 53
Output
UV sensor
Supply voltage for UV sensor UVS
54, 24
Voltage
safety circuit input
(AC mains voltage)
UV sensor for continuous
operation
Voltage supply for UV sensor UVC 1
57, 27,
36
Minimum air pressure
Connection for sensor 1 with pilot lamp to monitor the air pressure
58, 28,
37
Minimum air pressure
Connection for sensor 2 with pilot lamp to monitor the air pressure
59, 38
Valve proving system
Connection for the sensor of the valve proving system (tightness control pressure switch or
POC switch for checking the closed position)
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