Medium Voltage Capacitors

The traditional ALLFILM system of conventional medium and high voltage capacitors consists of aluminium foil and polypropylene, immersed completely in synthetic, flammable oil. Breakdowns in this kind of dielectric tend to result in permanent short circuits which take out the entire capacitor element, change the voltage conditions inside the capacitor and initiate a chain reaction of further failures of capacitor elements which will end up in the loss of the entire capacitor. In three-phase capacitors, this process is usually accompanied by the occurrence of phase asymmetries which may cause damage and catastrophic failure.

In our MSD^TM medium voltage capacitors, we are using the metallised polypropylene so well known from LV power factor correction. Instead of flat pack windings, our capacitance is formed by compact cylindrical windings, avoiding the mechanical stress at the edges of the ALLFILM flat packs. Dielectric breakdowns insulate and regenerate by themselves, domino-like failures of series-connected capacitor elements are impossible. The capacitance remains practically unchanged throughout the operating life which is of particular interest for applications with tuning or detuning reactors. By that, phase asymmetries are impossible, and the costly star point monitoring by MV capacitor protection relay, typical for ALLFILM capacitors, becomes obsolete.

In fault situations, MSD^TM capacitors do not create short circuits, hence they cannot be protected by blow-out fuses. The rising internal pressure can be reliably detected and signalled by the integrated pressure switch.

Unlike ALLFILM, MSD^TM is manufactured without flammable liquid impregnants, and filled instead with eco-friendly solid, plant-oil-based resin. This offers advantages when using these capacitors in sensitive environment, in applications with high vibration stress, and during disposal at a later stage.

Available as three-phase ( WYE ) units in the range from 50 to 400kvar, for mains up to 12kV, 50/60Hz. Design in accordance with IEC60871, 61071 and 60110.