US 7,002,321 B2 · Automatic power factor correction using power measurement chip

Abstract

An automatic power factor correction system, for an electrical power installation drawing varying levels of reactive power, measures an electrical parameter of the power drawn by a load of a power installation using a power measurement integrated circuit, the parameter being capable of indicating a level of reactive power drawn by the load, and couples a combination of capacitors to the power line to compensate for the level of reactive power indicated by the electrical parameter measured. In a first embodiment of the invention, the combination of power factor compensating capacitors is calculated from a signed value of reactive power drawn by the load. In a second embodiment, the compensating capacitor combination is calculated from a value of power factor for the load which is calculated from a ratio of an active power value to an apparent power value.

Claims20

Dependent claims

A power factor correction apparatus for power factor correcting an electrical installation including a power line having coupled thereto a load drawing AC electrical power including a potentially variable level of reactive power, said apparatus comprising:

(a) power sensor circuitry coupled to said power line and operative to detect an electrical parameter of electrical power drawn by said load which indicates a level of reactive power drawn by said load, said power sensor circuitry including a power measurement integrated circuit coupled to said power line;
(b) a plurality of reactance elements;
(c) switching circuitry controllable to couple said reactance elements to said power line individually or in selected combinations;
and
(d) a controller interfaced to said power sensor circuitry and said switching circuitry and operative, in response to said level of reactive power indicated by said electrical parameter, to cause said switching circuitry to couple an appropriate combination of said reactance elements to said power line to thereby minimize said level of reactive power indicated by said electrical parameter.

2 more elements

A method for power factor correcting an electrical power installation including a power line having coupled thereto a load drawing AC electrical power including a potentially variable level of reactive power, said method employing reactance elements and comprising the steps of:

(a) automatically measuring an electrical parameter of power drawn by said load using power sensor circuitry coupled to said power line, said power sensor circuitry including a power measurement integrated circuit, said electrical parameter being capable of indicating a level of reactive power drawn by said load;
and
(b) automatically coupling an appropriate combination of said reactance elements to said power line to thereby substantially minimize said level of reactive power indicated by said electrical parameter.

Dependencies are inferred from the claim text.

Automatic power factor correction using power measurement chip

Life of this patent

Automatic power factor correction using power measurement chip

Life of this patent

Abstract

Claims20