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It is common knowledge that faults in the mains can be extremely costly. In recent years, the liberalization of the power market and a growing proportion of non-linear loads in the network have led to an increase in supply problems. Loads, such as automation systems or data-processing installations, are highly sensitive to RF interference voltages or deviations of the mains voltage from the sinusoidal waveform.

The availability of such systems and installations is increased by reactors and filters that are, optimally adapted to the given requirements, mdexx reactors are used in all industries to reduce harmonics and to increase availability of plants and equipment.


Application examples for mdexx filters

Safely protect motors: mdexx du / dt filter

mdexx du / dt filters are often used in frequency converters in the industry. They maintain voltage rise rates of <500 V / μs. They ensure reliable protection of the motor by reducing voltage spikes to a defined value. With a rated voltage of 500 V +10% and permissible 4 kHz as the clock frequency, they are versatile and can be used extensively. The maximum motor cable length is 300 m for non-shielded cables and 200 m for shielded cables.


Sinusoidal voltage design: mdexx sinusoidal filter

If the motor is to be supplied with an almost sinusoidal voltage, as in many areas of industry or in private households, mdexx sine-wave filters are used. They maintain voltage rise rates of <500 V / μs. Especially for noise sensitive areas, they are ideal because they reduce the magnetic motor noise. With 480 V + 10% rated voltage and permissible 8 kHz as the clock frequency, they can be used over a wide range. The use of long motor cable lengths is, of course, also possible here: maximum 300 m with unshielded cable and 200 m with shielded cable.


du / dt filters consist of a limiting network – reactor combination, or just a reactor. The filter is used at the output of frequency converters, whereby the motor current flows through the choke. By connecting a filter to the three-phase system at the output of the frequency inverter, transient voltage peaks are reduced and the voltage gradients at the motor winding are limited to non-critical values ​​less than 500 V / μs. In addition, the du / dt filter reduces the capacitive charging current peaks when using long motor cables, which results from the capacitance of the motor supply line.

Information about motor cable lengths:

– 200 m shielded motor cable

– 300 m unshielded motor cable


The application areas are diverse and include medical technology, wind energy, shipping, automation technology, railway industry, drive technology, heavy duty truck, textile industry and many more.