Write any four differences between CT and PT.
CT
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PT
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CT corresponds to current transformer
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PT corresponds to potential transformer
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CT primary is connected in series with load and secondary winding is connected to a low range ammeter.
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PT primary is connected in parallel with high voltage of load and secondary winding is connected to a low range voltmeter.
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Secondary winding is never open circuited when primary carries current.
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No such restrictions are there for PT connection.
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Used for Range extension of ammeter, wattmeter & energymeter.
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Used for Range extension of voltmeter, wattmeter.
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Specified by their burden and nominal current ratio.
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Specified by their burden and nominal voltage ratio.
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Measured value of current = (reading of low range ammeter) x CT ratio
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Measured value of voltage = (reading of low range voltmeter) x PT ratio
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It is a step-up transformer.
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It is a step-down transformer
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