METHOD FOR SYNTHESIZING LAGGING VECTOR FOR MEASURING REACTIVE POWER IN WATTMETER

摘要

PURPOSE:To synthesize the lagging vector for measuring reactive power with simple constitution, by outputting the voltage between two wires and the voltage half the input voltage outputted respectively by two sets of transformers respectively in series. CONSTITUTION:A circuit 8 for forming the 90 deg. lagging vector of a line voltage vector is formed of two sets of transformers PT, PT' provided with windings C1 and C2, C'1 and C'2 of the same characteristic which are connected respectively between two wires and detect the line voltage and the voltage half the input voltage respectively. If the windings C1 and C'1 and C2 and C'2 are so connected in series that the 1-fold output and 1/2-fold output are respectively substrated, the current corresponding to the components of the 90 deg. lagging vector for measuring reactive power is outputted from the circuit 8. The two outputs of the circuit 8 are applied to the Hall elements 3A', 3B' of clamp cores 2A, 2B and the outputs of the elements 3A', 3B' are processed with differential amplifiers 6A', 6B' and an adder 7', whereby the lagging vector for measuring reactive power is synthesized with the simple constitution requiring no complicated circuits.