03-05-2017, 12:19 PM
what are the advantages of using captive transformer
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captive transformer
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what are the advantages of using captive transformer
04-05-2017, 09:08 AM
Captive transformer applications have been subject to very little recent publication. This configuration is sometimes used to power large motors, with loads such as a large cooler or a process compressor. The usual voltage level is 2.3 to 4.1 kV, and the motor size is usually 1000hp or larger. The idea for this paper came from the start-up work on the a3000-hp chiller machine, with a dry-type captive transformer.
A captive transformer is de-defined as a serial transformer with a large motor, where the transformer is under continuous load, and the combination is used in a startup application across the line. Both the transformer and the motor can be energized at the same time by a single switch in the primary circuit of the transformer. Alternatively, the motor can be started by a medium voltage motor starter on the secondary side of the transformer.
One of the reasons to consider a captive transformer for online startup is to ensure a higher starting torque for the process. In a remote operation, the transformer can be installed in the motor, and the voltage drop due to a long length of cable would be reduced to a minimum. Other reasons to consider would be if the required motor voltage were not available at the site, or to allow the use of an optimum motor other than the existing system voltage. Another advantage is that the voltage drop during motor start-up is isolated from other loads.
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