CAUTION
In order to enable automatic master changeover, the parameter Autorestart must be set
to ON.
Do not touch the keypad of the devices during the master replacement process. Other-
wise the master change process will be interrupted.
12. Operation at constant differential pressure
12.1. Introduction
The inverter may manage the speed of rotation of the pump in such a way as to maintain a constant
differential pressure between the delivery and the suction of the pump in circulation systems. For this
purpose, a differential pressure sensor is used or, alternatively, it is possible to use two identical pres-
sure sensors placed one in the suction and the other in the delivery of the pump. The absolute differ-
ence of the read values is performed by the device itself.
1
2
5
1
2
3
4
1: Inverter; 2: Pump; 3: Pressure sensor; 4: Pressure sensor; 5: Differential pressure sensor
NOTE
If the suction pressure is expected to drop below atmospheric pressure during operation,
absolute rather than relative pressure sensors must be used.
12.2. Electrical connections
The device may be connected to linear pressure sensors with 4 - 20 mA output. The supply voltage
range of the sensor must be such as to include the 15 V DC voltage with which the device supplies the
analog inputs.
If a differential pressure sensor is used, it is necessary to connect the sensor to the analog input 1, i.e:
• AN1: 4-20 mA signal (-)
• +15V: 15 VDC power supply (+)
If two pressure sensors are used, one sensor must be connected to analog input 1 while the other sen-
sor must be connected to analog input 2, i.e.:
• Sensor 1:
• AN1: 4-20 mA signal (-)
• +15V: 15 VDC power supply (+)
PSDrive
48
