CRMagnetics Catalog

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Technical Terms
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Applications
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Accuracy The degree of uncertainty with which a measured value agrees with the ideal values. Accuracy class of
instrument transformers are defined by the requirements of ANSI standard number C57.13. Standard
metering accuracy classes are 0.3, 0.6 and 1.2.
Ambient Temp Temperature of the surrounding air.
Apparent Power The product of the applied voltage and current in ac circuit. Apparent power, or volt-amps, is not the true
power of the circuit since power factor is not considered in the calculation.
Auxiliary Power A power source, other than that producing the measured input quantity, which supplies the power necessary
for the correct operation of the transducer.
Average RMS Responding The measurement of an AC voltage or current obtained using a DC instrument with a rectifying input circuit
that converts AC energy to DC. The meter scale or readout is usually calibrated in terms of the corresponding
RMS values, but is accurate only for pure sinewave inputs.
Burden In current or potential transformers burden in VA is the maximum load the transformer can support while
operating within its accuracy rating.
Calibration Adjustment of a transducer so the output is within a specified range for particular values of the input.
Current Transformer An instrument transformer used to accurately scale ac currents up or down, or to provide isolation. Generally
used to scale large primary or bus currents to usable values for measuring (or control) purposes. The current
measurement range is expressed as the ratio of full scale primary current to full scale secondary current. The
primary winding is connected in series with the conductor carrying the current to be measured or controlled.
There are two classification of current transformers. Window type and Wound Primary type. In Window type
current transformers the primary winding is provided by the line conductor and is not an integral part of the
transformer. In Wound Primary type the primary winding is an integral part of the transformers and usually
consist of more that one turn. Wound Primary transformers are used in applications that require very high
accuracies or where high voltage isolation is required.
Delay on Energization A term describing a mode of operation relative to timing devices. Delay begins when the initiate switch is
closed, or on application of power to the input. Same as Delay on Make.
Delay on Make Same as delay on energization.
Dielectric Strength The continuous voltage a dielectric can withstand without deteriorating.
Technical Terms
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