Fault Induced Wave Distortion of Interest to Relay Engineers

The diverse nature of arcing faults and switching effects at different system voltages is discussed in the context of the effects on the protective relay system. Distortion caused by transient nonlinearity of instrument transformers is also treated. Most forms of wave distortion appearing on the primary system are shown not to be suppressed by instrument transformers and hence also appear in the relay circuits. The transmission of wave distortion throughout the power system and into the protection circuits is discussed and shown to be predictable.