Nilfisk-Advance MC 6P Service Manual page 27

Function
D
Operation electrical System
Operation of MC 6P FA:
The PCB has following functions:
1. To start the motor when starting the machine.
2. To stop the motor when operation of the machine is finished.
3. To run the motor in by-pass for 20 sec. after water flow stop and B4 is "low" (open).
4. To record and store data concerning the machine work stiuation, operation and by-pass.
The PCB is protected by a fuse (630 mA—slow) placed on the board.
Pre-conditions: Machine hooked up to adequate water and power supply.
Main switch S1 in position "0" (OFF):
- There is main voltage at the terminal 1 and 2 on S1 and terminal 1,3 and 5 on K1, but no
power on the PCB
- Machine is still off.
Main switch S1 turned into position "1" (ON):
- Spray handle is closed; No water flow out of pump; if B4 is "low" and MT (motor winding
temp. below < 160°C or < 320°F) is closed, machine runs in by-pass for 20 sec. and stop.
- When the spray handle is activated there is a water flow out of the pump, because of the wa-
ter inlet pressure (direct water supply). The flow piston is moved up by the water flow and is
activating the reed switch B4 (goes high), and the PCBA powers the control power circuit with
24V AC. The contactor K1 is pulled by the contactor coil, and the motor starts, water flows out
of pump.
- Closing spray handle. Working pressure increases, pump switch to by-pass mode and have
no water flow - B4 goes "low", machine runs in by-pass for 20sec. and then stop.
SM_MC_6P Ver.2.0_2021
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