PURPOSE: To establish the phase angle converter in which the DC voltage proportional to the phase angle of two inputs is obtained and the discrimination of phase delay or lead can be made.

CONSTITUTION: The rectangular constant voltage circuit consisting of the resistor R1 and Zener diodes Z1 and Z2 is formed between the input terminals 1 and 2, and one output terminal of the circuit is connected to the first thyristor S1 and the second thyristors S2, S3 are connected to another terminal. Thus, the phase discrimination circuit obtaining the DC voltage proportional to the input phase angle between one and another input is formed. The current transformer CT converts the current i flowing between the input terminals 11 and 12 into suitable value current and is provided with the two output windings CT2 and CT3 to separate the cathodes of the thyristors S1 and S2, and S2 and S3. Positive and negative trigger can be obtained by inverting the direction of winding of CT2 and CT3.