When it comes to Filters, Siemens are True Masters of their Craft

"Drives Filters is where the Growth is" Says Steve Leggett Manager EMC Products Group"

Obviously the EMC directive created an increased demand for filters together with a proliferation of smaller manufactures but Siemens have still increased their market share.

SMD Chokes, Data Line, RF Chokes, X/Y Capacitors, Interference Suppression Filters, Converter Filters, and Filters for Shielded Rooms are all included in the extensive Siemens catalogue. However, Steve Leggett sees applications for Drives as the fastest potential growth market and it is to satisfy this demand where most new products will emanate from such as a new range of slim line book and footprint styled filters and the new 760V range.

Siemens was the only company to offer 690 volts and products up to 2500amps as standard. This is because special winding of the ferrite cores enables the filters to be made smaller, so it is no surprise that they have now introduced 760V three-phase AC line filters as a standard product range.

The voltage ratings of all new '690V' power filters have been modified. The old ratings of 690/400V have been upgraded to 760/440V. The extended voltage range widens the scope of application of the filters. Because the filters will keep the same order codes as their predecessors, all filter nameplates have been clearly marked to indicate the extended voltage range. Beyond this, the filter characteristics remain unchanged with the same consistently high quality.

In modern electrical drives, frequency converters control three-phase motors. This has the advantage that the speed of the motor can be precisely controlled, allowing for smooth acceleration and deceleration. The disadvantage that frequency converters are electro-magnetic polluters of the first order. Rapid switching operations at high currents with steep edges produce such high electromagnetic interference that entire production lines may be put out of action.

Such high-frequency interference can be suppressed with EMC filters designed specifically for converter applications. Different filters are needed according to the application, the connected load and the type of AC supply. Successful interference suppression of IT supply systems, for example, is particularly difficult since these are operated in isolation from ground. Up to now, standard filters have not been available.

The flagship of the new filter family has been developed specifically for 690V IT industrial supply systems and is suitable for current loads up to 3 x 2500A. For such a high connected load, the filter is remarkably compact, measuring only 65 x 32 x 22cm and weighing only 105kg. This new filter has a particularly high attenuation of 85dB, a volume resistance of only 15 mu Ohms, a leakage current of less than 6mA and power dissipation of only 280W.

The new family of standard filters for converter applications also includes models for conventional 690V IT networks (with the protective conductor incorporated in the cable) and a further series for 500V applications in IT systems. Different filters for rated currents up to 2500A are available as standard. The smallest 760V filters for TN systems are available for rated currents up to 3 x 25A; IT and 500V filters are available for maximum current loads starting at 150A. Typical applications for the new filters include frequency converters for electrical three-phase drives, such as those used in elevators, pumps, traction systems, conveyors, ventilation and air conditioning systems. They are also used for converters in wind energy plants and power supply systems.