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The plan is to break 2 circuits where four lines are terminated and connected to 2 bays breaker-and-a-half scheme. Then additional breaker-and-a-half bay for the new generation. Thanks

Hi All, Need help on this. We have an existing Double Circuit 138kV Grid Transmission Line with a length around 100km. Its a looped line where different generation sources and substations are connected at both ends of the 100km line. We are about to connect ("bus-in" or "cut-in") a 70MW...

Hello everyone, May i ask if how to represent the zero sequence equivalent circuit diagram of a single phase distribution transformer which primary winding is connected to phase A to ground of a four-wire system (A,B,C,N) or wye-grounded system? And its secondary winding is connected to a...

I would appreciate if you can recommend some references related to this parallel operation. Thanks.

Hi everyone, Would like to ask your ideas on how to do parallel operation for two transformers with different vector configuration, Dyn1 and Dyn11. If possible, what are the connections to be done? Regards, GRAEE

Ok, we have to route back out the shield to the CT window. I have another query on bus differential relay performance where it covers the whole length of the cable. The shield is within/between the zone of the bus differential and one end of the shield is grounded. Would that also affect the...

Dear Marmite, We're using single core unarmoured XLPE Insulated PVC Oversheathed Cable and this cable is lay down on the trench. What's the best practice?..Is it to connect one end of cable shield above the CT and brought back out through the window type CT and connect to ground? Or we left...

Dear davidbeach & Marmite, Thanks for the enlightenment. The cable shield ground is connected above the CT but only in one end, the other end is not grounded. As explained by davidbeach, we expect no return current for external fault. Regards, GRAEE

Dear All, Good day!!! Hope everyone doing well now. I have a query regarding the effect of power cable shield ground which is covered by the high-impedance bus differential relay with a window type CT as current analog input. Our bus is having 6 distribution feeders each with breaker and...

Zogzog, dpmac,oldfieldguy & smallgreek, Thanks for the response. This is actually a metalclad switchgear and 8 vacuum circuit breakers were drawn out to be tested. Only insulation resistance test was conducted. Taking all each insulation resistance per pole such as pole 1-to-ground, pole...

We have newly acquired 15 kV Switchgear and conducted insulation resistance test in all 6 poles (1,3,5,2,4,6). However the result varied significantly when the 2-4-6 poles are tested with respect to ground. Using the 5 kV, Vanguard-Insulation Resistance Tester, the largest insulation resistance...

Hello Juleselec & Sibeen, Thanks for the information. The relay that im referring is the old one, the BBC ICM2. Thanks very much. GRAEE

Hello everyone! What is the formula of a Normal Inverse Curve of BBC ICM overcurrent relays? Thanks.

scottf, The reading at the 138 kV side is 58.794 Hz while at the 13.8 kV side is 58.83 Hz. A 0.036 Hz difference is observed in both readings.

davidbeach, are different PT types & accuracies used for two voltage levels affect the frequency readings?

Hi All, May I ask your experience/explanation of the effect on measured frequency by two separate meters at different locations. We have two frequency meters connected at our 138 kV and 13.8 kV substations respectively...and are supplied by one source...Is there any possibility that they have...

Hello everyone! Im specifying the losses and impedance of a distribution transformer. I believe that all these parameters are affected by the efficiency being specified as well. In this regard, can you provide me a table on typical values of impedances & losses of distribution transformers? I...

MValles & ScottyUK, thanks for your recommendations. However, it would be convenient for us to use a detector with a video camera which captures SF6 leaks on circuit breakers. regards, GRAEE

MValles & ScottyUK thanks for your recommendations. However, we are into a detector with a video camera which captures the leak events.

Can anyone recommend brand & type of equipment which is used for detecting leaks of SF6 Circuit Breaker?