System for power overload factor measurements and for power overload protection of capacitive loads

摘要

1,118,829. Protective arrangements. POLITECHNIKA SZCZECIKSKA. 6 July, 1965 [6 July, 1964], No. 28612/65. Heading H2K. [Also in Division G1] A system for the measurement of power overload factor for capacitive loads in supply systems containing a large proportion of voltage harmonies, which may be used to operate a protective relay, is described. The power overload factor is defined as where n is the order of a given voltage harmonic, n p being the highest order in the supply, and k n is the ratio of the amplitude of the nth harmonic to the effective amplitude of the voltage supply. The voltage coil I of a wattmeter is connected across the supply in series with a corrective network 1 containing resistances and inductances so chosen that the current through the coil I is always directly proportional to k n for each harmonic in the supply. The current coil II is also connected across the supply, but in series with a capacitor C p , so that the current through this coil is proportional to nk n for each harmonic. These two currents cause the meter to set to a position proportional to W q , and the meter can be used to control a protective relay.