Specifications

When option module A and/or option module B is/are

used, the brim (B) must be fitted to the top cover (A).

NOTICE

Side-by-side installation is not possible when using the

IP21/IP4X/TYPE 1 Enclosure Kit

3.1.15 Output Filters

The high speed switching of the frequency converter

produces some secondary effects, which influence the

motor and the enclosed environment. These side effects

are addressed by 2 different filter types, the dU/dt and the

sine-wave filter.

dU/dt filters

Motor insulation stresses are often caused by the

combination of rapid voltage and current increase. The

rapid energy changes can also be reflected back to the

DC-line in the inverter and cause shut down. The dU/dt

filter is designed to reduce the voltage rise time/the rapid

energy change in the motor and by that intervention avoid

premature aging and flashover in the motor insulation.

dU/dt filters have a positive influence on the radiation of

magnetic noise in the cable that connects the frequency

converter to the motor. The voltage wave form is still

pulse shaped but the dU/dt ratio is reduced in comparison

with the installation without filter.

Sine-wave filters

Sine-wave filters are designed to let only low frequencies

pass. High frequencies are consequently shunted away

which results in a sinusoidal phase to phase voltage

waveform and sinusoidal current waveforms.

With the sinusoidal waveforms the use of special frequency

converter motors with reinforced insulation is no longer

needed. The acoustic noise from the motor is also damped

as a consequence of the wave condition.

Besides the features of the dU/dt filter, the sine-wave filter

also reduces insulation stress and bearing currents in the

motor thus leading to prolonged motor lifetime and longer

periods between services. Sine-wave filters enable use of

longer motor cables in applications where the motor is

installed far from the frequency converter. The length is

unfortunately limited because the filter does not reduce

leakage currents in the cables.

Selection

Design Guide