Sine-wave filter

Sine-wave filters limit the the rate of voltage rise (dv/dt) and the peak voltages on the motor winding. Similar to an output reactor, they enable the connection of longer motor cables.

Bearing currents are also reduced significantly. Using these filters therefore allows standard motors with standard insulation and without insulated bearings to be operated on SINAMICS. As a result, the voltage load on the motor winding is virtually identical to the load on windings of directly mains-fed motors.

Owing to the very low rates of voltage rise on the motor cable, the sine-wave filter also has a positive impact in terms of electromagnetic compatibility which means that it is not absolutely essential to use shielded cables for short motor cables to achieve the required standard of EMC.

Since the voltage applied to the motor is not pulsed, the inverter-related stray losses and additional noise in the motor are also reduced considerably and the noise level of the motor is similar to the level produced by directly mains-fed motors.

When using sine-wave filters, the following should be observed:

• Pulse frequencies of between 4 kHz and 8 kHz are permissible for rated outputs up to and including 90 kW
• Only a pulse frequency of 4 kHz is permissible for rated outputs of 110 kW and higher. Note additional current derating as compared with rated pulse frequency of 2 kHz (see derating data)
• The output frequency is limited to 150 Hz.
• Operation and commissioning may only be performed with the motor connected as the sine-wave filter is not no-load proof
• It must be ensured that the automatic pulse frequency reduction functions are also deactivated
• A derating of 5 % must be observed when the appropriate PM240 Power Module is selected?