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detection of voltage by Capacitive Divider Insulators

detection of voltage by Capacitive Divider Insulators

detection of voltage by Capacitive Divider Insulators

(OP)
Application
Indoor voltage divider insulators are used for the detection of the presence of voltage on phase lines.
The basic operation principle is on the capacitive division of phase voltage. The voltage divider insulators are used with capacitance coupled voltage indicating system.

OUR application
They were installed at 13.8kV of step-up transformer 500/13.8/13.8kV-400MVA-Ynd1d1. Each 13.8kV has derivation for 2 generator 60MVA and a derivation of auxiliary system.
Capacitive Divider Insulators are installed at each derivation to auxiliary system (2).
We are afraid ground fault stator(64E)protection of generators could operate for failure of this device.

What do you think about that?


 

RE: detection of voltage by Capacitive Divider Insulators

Would the generator operate for a fault on the bushing?
If your concerned about a failure or a fault then replace them.

If these are like the condencer bushing I remember, the tuning units are a bear to tune for even the addition or removal of a relay.

RE: detection of voltage by Capacitive Divider Insulators

Many of these systems actaully short out the bottom end of the bushing capacitor during normal operation, and you plug in a test unit when you want to determine if there is voltage present or not.  This helps save the detection lamps.  This would be just like your type of unit failing to a short circuit during operation.

The impedance of the bushing capacitance is very high, so it will not look like an earth fault any more than the same stand-off bushing that is bolted hard to earth does.

If still in doubt, ask the manunfacturer what your concerns are.  They'll probably be able to give you data on the impedance of the bushings.

ausphil

RE: detection of voltage by Capacitive Divider Insulators

(OP)
thank you guys
 manufacturer informed 150pF. It means an impedance of
 170 Mohm(60Hz). It is a good isolation.
 

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