COUPLING 1N3974 - Caterpillar

Parameters related to voltage regulation with cross current compensation (CCC) are listed below.:01 - Generator Output Voltage:02 - Ratio of Output Voltage to Sensing Voltage:03 - Generator Type:04 - Rated Generator Output Current:05 - CT Voltage At Rated Generator Current:06 - Knee Frequency:15 - Voltage Gain:16 - Integral Gain:17 - Proportional Gain:22 - Droop/CCC Select (only on part number 155-xxxx and later):30 - Droop PercentageCross current compensation is often used to minimize circulating current flow between the generators which are connected in parallel. The advantage of this operating mode is that all generators contribute to establish the same output voltage to the load. A utility voltage connection is not necessary to do so. Operation is similar to the reactive voltage droop mode except that the secondary circuits of the current measuring CT's of all generators are interconnected in a series string. Each generator is initially adjusted in order to provide the same output voltage via parameter :01. When all generators share the same current, in magnitude and phase (according to their CT ratio), there will be no significant voltage output on the secondary of any generator CT. If one of the generators carries more current or the current that the generator carries is lagging or leading relative to the others, a net difference voltage signal will be created on the burden resistor for that CT. If that generator is supplying more reactive (lagging) current than other generators, the phase polarity and the magnitude of the signal returned to the digital voltage regulator will be such to cause a slight decrease in the generated voltage, reducing the amount of reactive current. Less reactive (or more leading) current will cause the generator voltage to rise. The net result is that the generated voltage and the output current of each generator is trimmed toward an operating point where all generators will share the same load current in proportion to their CT ratio, with the little or no circulating current between them. Parameter :30 controls the amount of individual generator voltage droop (or rise) for a given amount of CT signal.However, because the CT secondary circuits are all interconnected, the CT signal seen by any individual regulator is not representative of the actual current flowing in that particular generator. Any display or calculations that might use that signal as if it were the actual generator current will provide erroneous results. This is the case with the digital voltage regulator on all models with part numbers of 130-xxxx or older (smaller prefix number). Beginning with regulator part numbers 155-xxxx and newer, another parameter was added to signal the digital voltage regulator when the CT is measuring differential compensation current or normal generator line current. Parameter :22 is used to notify the regulator that CCC is in effect, and to turn off the features that would be erroneous in that configuration. When parameter :22 is set to a "1" (CCC selected), the reverse VAR detection and optional reverse power fault detection are turned OFF,