Siemens Sinamics G120P Operating Instructions Manual page 301

Open-loop controlled fan
This is a basic fan application in which the fan is controlled by the inverter.
The system consists of the following components:
● Control Unit
● Power Module
● Motor
● Fan
● Belt monitoring sensor (optional)
● Motor temperature sensor (optional)
Closed-loop controlled fan
For this application, a constant air flow within a ventilation system should be maintained
while consuming as little energy as possible.
A fixed air flow and pressure for the fan system are specified in the inverter. These values
are monitored directly by the PID closed-loop controller. The inverter modifies the fan speed
appropriately when the pressure changes.
The system consists of the following components:
● Control Unit
● Power Module
● Motor
● Fan
● Actual value encoder (feedback)
● Motor temperature sensor (optional)
Fan switched in via PID
This application is used to operate several parallel-switched fans depending on the actual air
flow requirements.
One fan is controlled and monitored directly with the other fans being switched on and off as
required. A feedback from these other fans is not required. The monitoring is done using
pressure sensors together with the PID closed-loop controller. Cascade control is used, see
Cascade control (Page 408).
The analog inputs are used to set the setpoint and to receive the feedback signals from the
various sensors, to which the PID closed-loop controller then responds. The digital outputs
are used to control the fans.
When switched on, each fan runs with minimum frequency. This achieves a consistent
increase of the pressure and the air flow without producing an overpressure in the system.
Inverter cabinet units
Operating Instructions, 12/2014, A5E32923362A
Operation
6.10 Operation with the IOP
301