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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...

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

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...

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

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...

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

Im manually computing the zero sequence impedance of a line considering the ground wire. Can anybody provide me the simplified carsons equation?... for single circuit(with 3 conductors & 1 ground wire) and for double circuit (with 6 conductors & 2 ground wires). Regards,

Is it possible to operate generators in parallel which are connected in wye & delta? Assuming that all general requirements are met except that of their configurations.. thanks in advance

We have a 80,500:115 V oil-filled potential transformer stored horizontally instead in vertical position for almost 13 years already. What are the possible effects/problems may encounter on the performance of the PT when not properly stored? Does it affects the insulation or accuracy of the...

We have a 132 kVA, 3-phase,60-Hz, 240 volts-AC, with pf=0.8 stand-by generator. we're on the process of specifying the battery and charger system for genset starting purposes. It has a 12 volt-DC starter motor. can you give us inputs and guidance on how to do the specification? thanks,

Have read some references regarding this subject but it seems that there areas in the power system that these two will go hand in hand. Can somebody provide me a clear definition of the two and how it differs from one point to another?

We have a 67 relay (directional relay) and a power circuit breaker with 3-CTs connected in wye-grounded of 500:5 Amps tap used. Kindly see attached diagram for details. We injected current at the primary side of the breaker specifically at phase B where the phases A & B CTs were shorted. We...

Hello everybody, would like to solicit methods or practices used in testing the integrity of the insulation of 69 kV lines. We have a Megger-MIT 520 (insulation tester) with maximum voltage of 5kV can be injected. Is this enough for testing the insulation of a 69 kV line of about 15-20 km long?

We have a two-50 MVA autotransformer, 138kV-Wye Grounded/69kV-Wye Grounded/13.8kV-Delta, operating in parallel with %IZ, Zps=10.3%, Zpt=0.2% and Zst=5.5%. Only the 138 & 69kV sides are connected in parallel. I'm in the process of determining the appropriate Zero Sequence Impedance Equivalent...