The paper presents measurement results of a power quality monitoring on the industrial plant. The measurements proved that supply conditions are correct, but a cumulative effect of increasing use of electrical and electronic equipment and electrical disturbances can have an important impact on the electromagnetic compatibility. A case of possible resonance between power factor correction capacitors and the stray inductance of the supply system at or near one of the harmonic frequencies is described. When this happens, high voltages and currents can be generated often leading to catastrofic failure of the power electronic equipment.

Keywords: Electromagnetic compatibility, Harmonics, Power quality, Transients.