working of distortion factor meter with block diagram
Working : Initially the switch S is kept at position 1.The attenuator gets excluded and the bridge T network is adjusted for full suppression of fundamental frequency and hence we get minimum output condition.This condition indicated that the bridge T network is tuned to the fundamental frequency with full suppression of it.Then switch is moved at position 2, then the bridge T network is excluded.The attenuator is adjusted such that same reading as previous is obtained on the meter.Thus the total rms distortion is indicated by the reading of attenuator.