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Home > Archive > Electrical Engineering > June 2007 > Overvoltage of shunt capacitors
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Overvoltage of shunt capacitors
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| kelfookf 2007-06-26, 5:25 pm |
| This is mention in a book that I don't quite understand how it happens
"There are several disadvantages to mechanically switched
capacitors. ... If voltage collapse results in a systems in a system
breakup, the stable parts of the system may experience damaging
overvoltages immediately following separation. "
Cheers,
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| daestrom 2007-06-29, 5:25 pm |
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"kelfookf" <kelfookf@gmail.com> wrote in message
news:1182888643.888767.309900@e9g2000prf.googlegroups.com...
> This is mention in a book that I don't quite understand how it happens
>
>
> "There are several disadvantages to mechanically switched
> capacitors. ... If voltage collapse results in a systems in a system
> breakup, the stable parts of the system may experience damaging
> overvoltages immediately following separation. "
>
As Don pointed out, having capacitors at the end of an inductive line is a
common practice to compensate for any inductive loads placed on the line.
(having an inductive load on an inductive line results in pretty severe
voltage drop without any compensation)
Mechanical switches that are automatically controlled to maintain line
voltage at the load end will switch caps in/out as load increases/decreases.
But they react rather slowly, they are designed to 'follow' with normal load
fluctuations.
When a system starts to trip lines and 'break up', the inductive load can be
lost much faster (like a single breaker tripping). The mechancial switch
won't disconnect the caps fast enough and the large capacitance at the end
of an inductive line can result in very high voltages.
daestrom
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