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Paralleling Motor Generator Sets

IP.com Disclosure Number: IPCOM000076564D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Koranye, TD: AUTHOR

Abstract

Circuit 10 of Fig. 1 places the two outputs of motor generator sets 11 and 12 on a power bus, not shown, when the two are in phase.

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Paralleling Motor Generator Sets

Circuit 10 of Fig. 1 places the two outputs of motor generator sets 11 and 12 on a power bus, not shown, when the two are in phase.

For purposes of explanation, it is assumed that set 12 is on line and providing power. Set 11 is about to be connected to the line to assist set 12. The phase- to-phase voltages of set 11 are the same as set 12 and phase rotation is also the same. It is further assumed that set 11 is running faster than set 12.

In operation, the output signal present across winding 14 of transformer 15 provides a zero-voltage crossover at the instant the outputs of sets 11, 12 are in phase. The period between successive zero crossovers increases as the two sets approach synchronism, c.f. Fig. 2.

The transformer output signal at winding 14 is rectified by respective diodes 17 and 18. The RC time constants of circuits C1, R1 and C2, R2 are such that the rectified output signal X1 turns off transistor T1 at approximately each zero crossover; whereas, the rectified output signal X2 does not allow transistor T2 to turn off until the aforementioned period of the zero crossovers is at the value associated with the condition when the two sets 11 and 12 are in synchronism. When transistors T1 and T2 are both off, the silicon-control rectifier gate 19 becomes forward biased and thereby energizes the relay coil 13A associated with the armature 13, thereby closing the normally open armatures 13B, 13C with their respective contact...