Sensors And Actors - Nilfisk-ALTO NEPTUNE 4 FA Service Manual

Function
D
Fig.D.3: Sensors & actors
Sensors:
B1: Temperature sensor in the outlet from the boiler. Controls the combustion (Y1 on/off) according
to setting.
B2: Flow switch senses the flow out of the pump into the boiler and controls solenoid Y1 on/off.
B3: Safety thermal switch placed in the exhaust of the machine, if temperature > 270°C/ 518°F will
switch off, if the burner keeps burning without water flow through the boiler. The safety thermal
switch must be reset manually in the electrical box.
B4: Flow switch controls the motor start/stop. When pressure is higher than working pressure the
switch will open and the motor stops.
B6: Oil level-sensor stops the machine if the pump is low on oil. Activates red light on panel.
B7: Flame-sensor detects light from the flame. If the flame is not detected when it should be there,
the machine will be stopped.
B8: Level switch Anti-Stone liquid. If low, yellow light will light up.
B9: Level switch fuel (stops the fuel valve) when low on fuel and yellow light appears on the panel.
MT: Temperature switch stops the motor if the temperature in the windings is >160°C/ 320°F.
Automatic reset.
Actors:
Y1 Solenoid opens/closes the fuel for the burner.
T2: Ignition transformer is on when burner fan is running.
The machine is supplied with main power which is transformed into 8V AC to supply the micropro-
cessor and sensors and 24VAC to supply the actors (contactor, relay, solenoid valve).
To run the machine on hot water the following must be ok: on the front panel S1 and the temperatu-
re setting on hot and the spray handle open. If all the sensors are closed and ok K1 will start the mo-
tor and K2 the ignition and fan. Y1 will open and let in oil to the combustion chamber. If the flow
stops B2 will open and the 24V supply to the solenoid Y1 will be interrupted and the combustion will
stop.
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