Selection and operation of compressors with external frequency inverter (third-party product)

For the released frequency range of the Bock compressor, see technical data or at min./max. cooling capacity.

The maximum permissible working current of the compressor (I_max,comp) (see technical data) must not be exceeded.
If abnormal vibrations occur in the system, the affected frequency ranges has to be blanked out in the frequency converter accordingly.

The maximum output current of the frequency converter must be greater than I_max,comp.
For a safe start of the compressor, the frequency converter, for applications with low pressure refrigerants HP up to 28/32 bar, must be able to supply a short-term overload of min. 140% of I_max,comp for min. 3 seconds.
For applications with high pressure refrigerants (e.g. CO₂) a value of min. 160% of I_max,comp for min. 3 sec has to be supplied.

Carry out all designs and installations in accordance with local safety regulations and common regulations (e.g. VDE), as well as the specifications of the frequency inverter manufacturer.

Notes on CO2 Compressors with LSPM Motors

For CO2 compressors with LSPM motors that are operated with a frequency inverter, the Y-connection of the motor must match the mains voltage. However, the compressor should be connected to the inverter in the Δ-connection. The inverter must be sized for the higher currents of the Δ-connection.

Notes regarding capacity data

When compressor is operated with frequency inverter the capacity data is calculated out of the 50Hz-data and is intended as an assistance to determine the capacity data at different frequencies. Deviations cannot be excluded.