7Equipment protection
3 Equipment protection
3.1 Pressure switch (inlet water)
The HP and HPRO have a pressure switch which monitors the inlet water pressure.
If the inlet water pressure drops, the controller will stop the pump, thus protecting the pump(s) against
dry running. If the water pressure drops, the screen will show “PM Water pressure too low”
3.2 Max. Hygrostat to protect against excessive humidication (option)
It is possible to connect a Max. Hygrostat to the control cabinet. If humidity levels rise to a value that
exceeds the value set on the Max. Hygrostat, the system will stop and the alarm lamp ashes. The
system will not restart until the alarm is acknowledged by pressing ‘Alarm reset’. If this function is not
required, the input will short-circuit on the terminal block.
3.3 Temperature switch
The high-pressure pump is protected against overheating by a temperature circuit that measures the
current temperature in the pump. The temperature limits can be set individually.
Default settings:
1. If the temperature exceeds 30 °C, the control unit will initially attempt cooling by starting the water
treatment part and lling up the tank with cold water. – If this makes the temperature drop to below
30 °C, this function will reset and everything will continue unchanged. While the tank is being lled,
the high-pressure pump will continue unaffected.
2. If instead the temperature continues to rise to above 40 °C, the pump will stop and start emptying
the tank of overheated water and produce new water in the tank. During this process and until the
start level has been reached, the pump will remain idle with the alarm text displayed. The pump will
start automatically once the start level has been reached.
3. If the temperature exceeds 50 °C, the pump will stop immediately and must be reactivated via the
reset button once the temperature has dropped again.
3.4 Phase sequence relay
The control unit is equipped with a phase sequence relay, which protects against incorrect connection
of the supply cable. Both LEDs on relay E1, which is located in the cabinet to the right, must be lit.
When both LEDs are lit, the pumps will run correctly. The relay also protects against fuse breaking.