ENGINE AR- 3878568 - Caterpillar

Illustration 1 g00885654
Cross current compensation (CCC) is often used to minimize circulating current flow between the generators which are connected in parallel. All generators contribute toward establishing the same output voltage to the load. The operation is similar to the reactive voltage droop mode, except that the secondary circuits of the current transformers of all generators are interconnected in series. Each generator is initially adjusted in order to provide the same output voltage.When all generators share the same current according to the current transformer (CT) ratio, there will be no significant voltage output on the secondary winding of any current transformer (CT) for the generators. A net difference voltage signal will be created on the burden resistor for that current transformer (CT) if one of the generators carries more current.If the current that is being carried by the generator is lagging relative to the other generators or leading relative to the other generators, a net difference voltage signal will be created on the burden resistor for that current transformer (CT).If that generator is supplying more reactive current than other generators, the polarity and the magnitude of the signal that is returned to the voltage regulator will cause a slight decrease in the voltage that is generated. This will reduce the amount of reactive current. Less reactive current will cause the generator voltage to rise. The output voltage and current of each generator is trimmed toward an operating point. All generators will share the same load current at that operating point. This current will be in proportion to the CT ratio. There will be little or no circulating current between generators.