APPENDIX 29
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Appendix 7 Glossary of Terms
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Appendix 7 Glossary of Terms
RMS:
Root Mean Square value for a voltage or current waveform. This value is used
to represent the size of an AC signal. Because the 3166 converts waveform
data to a digital signal before performing this operation, even distorted signals
can be measured accurately.
CT:
Current Transformer. When measuring strong current, the current
transformer is used to reduce the current to an appropriate level before
supplying it to the power meter.
CT ratio:
This ratio is used to convert the current value on the secondary side of the CT
to the primary side.
PT:
Potential Transformer. When measuring high voltage, the potential
transformer is used to reduce the voltage to an appropriate level before
supplying it to the power meter.
PT ratio:
This ratio is used to convert the voltage value on the secondary side of the PT
to the primary side.
Chattering:
When a relay contact closes, chattering is a phenomenon in which the contact
does not close right away but quickly opens and closes repeatedly.
PLL:
Phase Locked Loop. Synchronization is attained with the base wave
component of the signal being measured, and the signal is constantly sampled
at 256 points over two cycles.
D/A output:
Although this is also generally known as analog output, the 3166 is a digital
sampling power meter, and therefore all measured values are processed
digitally. Therefore, the analog output is derived from digital data that is
converted into analog signals.
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