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The power disturbance generator is not only useful for the tests presented here, but can also
be used for identifying equipment that is adversely affected by voltage disturbances. The
power disturbance generator is significantly less expensive than existing power disturbance
generators, has a significantly higher power rating, can operate indoors, and is portable so it
can be easily transported and maneuvered around most industrial facilities. The voltage
rating is 600Vac and the current rating is 400Aac continuous, 5kAac for 10ms. However,
these ratings can easily be increased without sacrificing portability. The drop-out time, the
pick-up time, and the interruption duration are all point-on-wave (POW) adjustable in 0.01
cycle increments.
B.1 Control Circuit
A 600V
rms
to 12V
rms
control transformer, XFMR1, is used to provide the reference between
the power circuit and the control circuit. Specifically, the supply voltage reference waveform
is the voltage measured at Phase A with respect to Phase B (Phase A-B). From this reference
waveform, two clock signals are generated, a 60Hz clock signal and a 6kHz clock signal.
The 60Hz clock signal is generated by feeding the supply voltage reference waveform into a
zero-crossing detector, which is followed by an opto-isolator. In this case, the opto-isolator
is used only to help with noise immunity. It's not intended to provide additional isolation.
Transformer XMFR1 provides the necessary isolation between the control circuit and power
circuit and is also the device which limits the voltage rating to 600Vac. The voltage rating of
the IGCTs is 4.5kV, so simply installing a different transformer will increase the voltage
rating substantially.
The 6kHz clock signal is generated by feeding the 60Hz. clock signal into a phase-lock-loop
(PLL), which is used as a times 100 frequency multiplier. One 60Hz clock cycle corresponds
with one cycle of the power circuit supply voltage and one cycle of the 6kHz clock cycle
corresponds with 0.01 of a cycle of the power circuit supply voltage
Appendix B
Portable Power Disturbance Generator