Patent ID: 6704214
Filing Date: 2004-03-09
Classification: H02P

Abstract:
An excitation control system for outputting an excitation voltage for a rotating electrical apparatus, said excitation control system comprising:an electrical switching apparatus comprising a plurality of input terminals including a plurality of alternating current phases, a plurality of output terminals, a plurality of separable contacts electrically connected between said input and output terminals, and an input to open said separable contacts, said electrical switching apparatus providing the alternating current phases at said output terminals when said separable contacts are closed; a rectifier bridge comprising a plurality of inputs electrically interconnected with the output terminals of said electrical switching apparatus, a plurality of segments to convert said alternating current phases to said excitation voltage, and an output having said excitation voltage, each of said segments including an element having an input responsive to one of a plurality of firing signals; and a controller comprising: an input including a first signal, an output including a second signal, the output of said controller being electrically interconnected with the input of said electrical switching apparatus, a first value, a second value, a first sensor inputting at least one voltage corresponding to the alternating current phases of said electrical switching apparatus and outputting a sensed voltage, a second sensor inputting said excitation voltage of the output of said rectifier bridge and outputting a sensed excitation voltage, a plurality of outputs, each of said outputs electrically interconnected with the input of the element of a corresponding one of said segments of said rectifier bridge to provide a corresponding one of the firing signals thereto, a first function detecting the first signal and responsively controlling the firing signals of the outputs of said controller in order to provide said excitation voltage having a negative value, a second function, and a third function determining if the first signal is asserted and responsively delaying for a predetermined time, unless the second value is greater than the sensed excitation voltage, and after said predetermined time responsively asserting the second signal, in order to open the separable contacts of said electrical switching apparatus and remove the alternating current phases from the inputs of said rectifier bridge.