Harmonic Filters

The ever-increasing use of power electronics and other solid state devices which generate harmonic voltages make the issue of power quality more and more important both for suppliers and users of electrical power.

These harmonic voltages can increase line losses and also have a detrimental effect on other users of the network. Harmonics can be reduced to acceptable levels by passive filter circuits consisting of inductors, capacitors and resistors.

The capacitors and inductors allow through the fundamental frequency and divert the harmonics into the filter resistor where the harmonic currents are dissipated as heat and thus lost from the system.

Low inductance is a key feature for the design of filter resistors. Cressalls expanded mesh and woven mat resistors have very low self-inductance and are particularly suitable for operation at high voltages in the following applications: Static VAr compensators (SVCs) HVDC transmission systems Mechanically Switched Capacitor Damping Networks (MSCDNs) Industrial harmonic filters

Harmonic Filters

Cressall have supplied resistors for use within filter systems at every level of the electrical distribution system, from 400kV Grid transformers to 415V industrial equipment, and with power ratings from a few watts to several megawatts.