26
3.1 Functionality
2
In 1 In 2
7
6
1
5
3
4
Level control
1: Sensor 1 with normally closed output for input 1 (upper level)
2: Sensor 2 with normally open output for input 2 (lower level)
3: Tank with liquid or dry bulk material
4: Valve or pump (inlet)
5: Relay output
6: Transistor output
7: PLC or signalling device
Process
Relay
After switching on the device
de-energised
Level is below both sensors
energised
Level is above both sensors
de-energised
Level is between the sensors
depending on the previous state
Relay energised, i�e� switched (transistor output switched)
