Fig. 19 Droop C.T. Positions

Operation - TM-55-1930-209-14P-9-4_817

Setting Up Procedure for Parallel Operation

TM-55-1930-209-14P-9-4 Water Purification Barges (NSN 1930-01-234-2165) Electric Power System Manual
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The other important factor is to ensure that the voltage produced across the burden resistor/choke adds with the A.V.R. sensing voltage in the correct direction. If for any reason this is reversed, a rising characteristic will result which will give an unstable condition for parallel operation and will produce high circulating currents. This can be checked quite simply by applying a unity p.f. load on each machine separately and measuring the voltage across auxiliary terminals 6 to 2 and 6 to 8 on the two phase sensed A.V.R. and across auxiliary terminals 6 to 7 and 6 to 4 on the three phase sensed A.V.R. If the circuit is functioning correctly, the voltage across 6 to 2 should be less than the voltage across 6 to 8 and the voltage across 6 to 7 should be less than the voltage across 6 to 4. A.V.R. Stator Connection Paralleling Quadrature Droop Astatic Type (Standard phase rotation) Fig. C.T. Position Fig. C.T. Position Two 4 Wire & 6 Wire Star 16 W2 Series Star 16 W2 Phase 12 Wire Series Delta 16 W2 Not available Parallel Star 16 W2 Sensed Series Zig-Zag Star 17 W2 Three 4 Wire & 6 Wire Star 17 V2 Series Star 17 V2 Phase 12 Wire Series Delta 16* W2 Not available Parallel Star 17 V2 Sensed Series Zig-Zag Star 16* V2 Fig. 19 Droop C.T. Positions NOTES: 1. *For these stator connections the C.T. secondary leads S1 and S2 must be reversed for correct machine operation. 2. Standard phase rotation is U.V.W. when a.c. generator is rotating clockwise viewed at the drive end. For phase rotation U.V.W. when rotating anti-clockwise refer to factory for details. General Notes on Paralleling Main Metering Requirements For successful synchronization and load sharing between two or more a.c. generators, the following meters and equipment are essential: Voltmeter This can be one voltmeter per machine, or one which is switchable to either. The latter is more accurate for initial voltage setting to ensure identical voltages. Another voltmeter may be fitted to the main bus-bars for monitoring the machine on load. Ammeter At least one ammeter per machine is required, preferably with phase to phase switching. Wattmeter At least one wattmeter per machine is essential to observe the load sharing of the prime movers, i.e. engines. Frequency Meter As with the voltmeter, this can be one per machine or preferably one which is switchable to either, and another registering the bus-bar frequency. 37

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