Abstract: A filter module for a frequency converter comprises a filter circuit housed in a casing adapted for connection to the converter. The filter module includes an input filter and an output filter so arranged that input terminals for connection to the AC line voltage and output terminals for connection to an electric motor are disposed on a common side of the casing and so that the connections between the frequency converter and the filter module are disposed on a side of the casing which in use faces the converter.

Abstract: An add-on module for a variable speed drive includes a casing containing an electronic circuit and a connector to plug into a corresponding connector on the variable speed drive. The casing is generally L-shaped with a front portion carrying the connector and positioned along the front of the variable speed drive and a side portion accommodated on one side of the variable speed drive. The electronic circuit includes front and side printed circuit boards electrically connected to each other and the angle between which is substantially equal to the angle between the two portions of the casing.