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30 Cards in this Set
- Front
- Back
Harmonic |
Voltage or current at a frequency that is a whole number (integer) of the fundamental frequency |
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Notch |
Distortion in voltage waveform where voltage quickly drops toward zero,then returns to correct value |
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Common mode noise |
Electromagnetic interference induced on power or communication lines |
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Choke |
Reactor used to restrict the current to ac or DC drives in the case of short circuits in the drive itself |
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Total demand distortion |
Ratio of current harmonics to the max load current |
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Harmonic mitigating transformer |
Transformer designed to reduce harmonics but not remove in a power distribution system |
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Harmonic filter |
Device used to reduce harmonic frequencies and thd |
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The most effecient way to send electric power over transmission lines |
The lowest current possible |
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Reactance |
The opposition to current flow in an ac circuit |
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Electrostatic shields |
Can prevent common mode noise only if secondary is ungrounded |
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Output reactors |
Help eliminate voltage spikes by slowing down the rate of change in a drive output voltage |
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3 benefits with grounding the secondary of a drive isolated transformer |
Impulse immunity to load side,reduce common mode noise,prevents induced ground current upstream |
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Drive isolation transformer |
Designed with additional reactance for non linear loads |
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Auto transformer reduce voltage motor starting by |
50,65,80 percent to the line voltage |
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Harmonic sequence |
Is the phasor rotation with respect to the fundamental (60)hertz frequency |
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Phasor rotation |
Is the order in which waveforms from each phase cross zero |
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Total harmonic distortion |
Amount of harmonics on a line compared to the fundamental frequency (60)hertz |
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Power factor |
Ratio of true power to apparent power ptrue/papparent |
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True power |
Is the power in watt or k watts used in motors or lights |
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Reactive power |
Is the power in var or kvar ..stored and released by capacitors and inductors |
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Harmonic power |
Is the power in VA or kvar lost to distortion |
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Apparent power |
Is the power in VA or kva..sum of true,reactive and harmonic power |
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Displacement power factor |
Ratio of true power to apparent power due to phase displacement |
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Distortion power factor |
Ratio of true power to apparent power due to( thd) total harmonic distortion |
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Current crest factor |
Is the peak value of a wave for divided by the rms value of a waveform |
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Ballast |
Controller for providing initial start up voltage and keep a constant current thru the lamp |
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Fourier transformer |
Mathematical method of converting a time based waveform into frequency based information |
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Reactor,line reactor |
Coil added in series with a load to reduce inrush current |
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Saturable core reactor |
Inductor who's inductance is controlled thru the use of magnetic field created by a second winding wound around the same iron core as the primary winding |
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Auto transformer |
Is any transformer In which the primary and secondary circuits have a portion of their two windings in common |