Problem In CCPD

Tell me there isn't a loose connection in the r phase, Murphy. Something that only appears when the temperature is lower.

Do you have any capacitors being switched on/off line?

Are there large motors/transformers or similar, being switched at night nearby?

Maybe from another company?

What about a modern 3 phase voltage monitor(s) being installed till the problem is found....?

Renting is the usual method in my time....though a purchase could pay for itself......

actually there are four 500kv transmission lines from our station.Only indication is on this line.capacitors are not installed on this line.I think motors should not effect such a large system

You know what thought did!!! Of course large motors affect the power delivery around them!!

You now need to tie in the time of the problem and a change of "running" in those motors......or not!!

You must be on a very good & high pay scale to be allowed to do what you are doing.

I recognise the ccpd schematic you posted, it is a circuit to reduce neutral(earth) & secondary voltage distortion in the Cap EVT.

Your problem may be solved with other ballast or different settings in the ccpd.

Refer problem to Siemens, the probable maker of the ccpd, for assistance.

CCPD,

Something about this problem niggles in my 80 year old brain about an experience on duo-bias transformer protection about 35 years ago.

Every thing worked out on commissioning tests except the switching to check the magnetic inrush, it was found that the interconnecting tertiary circuit was not connected between the separate phase relays.

You may have a similar problem, I think there should be a interconnected tertiary circuit between the separate phase CCPD's that is either not connected or open circuit. Compare the CCPD connections with the other line CCPD's.

I still recommend you contact an expert of the CCPD maker.

we have changed the blue phase ccpd of the line.lets see what happens today or tonight.I have uploaded the drawing for the connection of the ccpd.

CCPD - you mean Capacitive Voltage Transformer (CVT) I guess.

It seems the capacitor in CVT is having problems.

May be, it is time to replace.

I remember working as a contractor at a cement plant and they had some equipment there that they were asked by the local power company to start only at night during low load conditions and furthermore they were supposed to call the power company prior to starting or stopping this equipment due to load fluctuations demanded by the plant. Perhaps this is similar situation as previously stated.

it has been a week since we replaced the blue phase ccpd.The problem has not appeared again.But the results of removed ccpd are perfect.

Hi mate, check your Voltage Transformer Neutral connections (Primary and Secondary)

Some times there is loose connections or bad connections to "EARTH" then you have floating neutral which causes this problems of voltages not correct

Good luck