Filters

SinECOTM passive electric passive filters and TRAFECO filters, are dedicated for use in drive systems powered and regulated by voltage inverters. Despite the undeniable advantages of inverter drives, the modulated output signal is often a source of adverse effects on the power cable and the regulated motor. High keying frequencies and the accompanying high steepness of the du/dt voltage pulses are the cause of voltage stress in the insulation of the supply cable and the motor. Large du/dt steepnesses are a common cause of cable or motor damage. High frequencies of the inverter output voltage result in higher values of ground and screen currents. The solution to these technical problems is to use a sinusoidal filter of the SinECOTM type at the output of the inverter. They restore the sinusoidal shape of the inverter voltage by limiting the voltage harmonic amplitudes to THDu values below 5%. This protects the motor and cable insulation system and eliminates dangerous reflection voltages on the motor. A passive sinusoidal filter consists of an inductive choke and appropriately selected capacitors. Capacitors for this application are ordered in a special design to withstand the unfavourable high du/dt voltage steepness. Chokes, on the other hand, are made with the low-loss CoreECOTM multi-slot technology, which significantly reduces the flux of the core of the choke, which has the effect of reducing the additional loss and limiting the acoustic field around the choke.

Most popular inverters even of high power have a rectifier in the input circuit in a six-pulse bridge arrangement. Such a rectifier draws a relatively strongly distorted current from the mains during operation. The harmonics of the mains current also place a heavy load on the mains transformer windings. Because of the large number of non-linear loads in plants, power transformers are often oversized, taking into account the additional losses due to current harmonics (K factor). ThdECOTM type harmonic filters are devices designed to operate in the supply circuit of typical inverters with a six-pulse input rectifier. These filters limit the harmonic content of the current drawn from the mains to less than 5% THDi, allowing compliance with IEEE 519-1992 and PN-EN 61000-3-12 standards. In facilities where harmonic filters are applied to large drives and non-linear loads, it is not necessary to oversize the mains transformer. Harmonic filters protect the power transformer windings from overload by current harmonics.

SinECOTM sinusoidal filters and ThdECOTM harmonic filters can be supplied in IP23, IP44 or IP54 rated housings. The housings are sized to guarantee cooling and correct operation of the equipment. In the case of self-installation of filters in sealed casings, the casing must be selected so that its surface can absorb the losses generated by the filter. Upon agreement, we can design and manufacture filters for any voltage level, non-standard operating conditions in any climatic zone.

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