Answer / yasser

Corona Inception

Corona inception voltage is the lowest voltage at which
continuous corona of specified
pulse amplitude occurs as the applied voltage is gradually
increased. Corona inception
voltage decreases as the frequency of the applied voltage
increases.
Corona can occur in applications as low as 300V.

Corona Extinction

Corona extinction voltage is the highest voltage at which
continuous corona of specified
pulse amplitude no longer occurs as the applied voltage is
gradually decreased from above
the corona inception value. Thus, once corona starts, the
voltage must be decreased to get
it to stop.

CFVV - constant flux voltage variation

The short notation of tapping range and tapping steps
indicates the variation range of the
ratio of the transformer. But the assigned values of tapping
quantities are not fully defined by
this alone. Additional information is necessary. This can be
given either in tabular form with
tapping power, tapping voltage and tapping current for each
tapping, or as text, indicating
'category of voltage variation' and possible limitations of
the range within which the tappings
are 'full-power tappings'.
Thus CFVV is defined as the tapping voltage in any untapped
winding is constant from tapping to tapping. The tapping
voltages in the tapped winding are proportional to the
tapping factors.

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