7. Compressor module (VSD)
37
Analog input AI-2
This analog input detects the speed of the compressor.
To measure the speed of the compressor, one phase of
the motor leads has to be wired through the current
transducer supplied. This must be connected to the
compressor module using the cable supplied.
This enables the module to measure the current of the
compressor motor and to calculate the speed using the
parameter settings in the GD Connect 12.
Analog output AO-1
Danger
For compressors that are not equipped with
independent over-pressure detection it is
recommended that a pressure switch be
incorporated in the compressor fault circuit(s) such
that any local over-pressure condition will stop the
compressor independently from the GD Connect 12.
The analog output is used for regulating the speed of
the compressor motor.
This is done by connecting the analog output to the
analog input at the compressor control which is
normally used to connect the line pressure sensor.
If the compressor module changes the signal of the
analog output to reduce the line pressure, the speed of
the compressor will be increased and vice versa.
Fig. 11 shows the relation between the analog inputs
and outputs on the compressor module and the
compressor control.
Compressor module
Fig. 11 – Relation between analog inputs and outputs
Note
On connection of analog input AI-1 and analog output
AO-1, the line pressure measured at the line pressure
sensor will be displayed correctly at the compressor
control even if power is lost at the compressor module
(VSD).
Note
An amplifier can be connected between analog output
AO-1 and the analog input of the compressor control if
necessary.
Compressor control
Analog input
Line pressure sensor
Compressor
line pressure sensor
AO-1
Compressor module
(VSD)
AI-1
