The 100ADM-F Filter Unit reduces the level of current harmonics when testing electro-mechanical protection relays. It is designed for use with our range of secondary injection test sets.

All electro-mechanical protection relays have iron cores that saturate and distort the test current under high overload test conditions. The distortion causes significant errors in the measured trip time of these relays during testing. Distortion of the waveform can be a particular problem with disc induction type over-current and sensitive earth fault relays.