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Hi all, I will be installing a Zig-Zag transformer to provide a ground reference for a 69kV delta system. This Zig-Zag TR will be installed in conjuction with a two-winding power transformer where the phasing into the power transformer is Phase 1 into the H1 bushing, Phase 2 into the H2...

We have a number of drawings that were intended as 2D plan and elevation drawings. Somehow, some 3D attributes were mixed into the drawings, which is creating some problems. With people cutting and pasting objects to and from drawings, this seems to be spreading. Is there any easy way to...

We have a client that is interested in taking a negative sequence voltage measurement back to their DFR. From looking at their schemes, they don't appear to have any relay or device capable of producing a negative sequence voltage output for use by the DFR. 1. Does anyone know of an old...

I am looking for documentation on a TRW 9550 RTU. Does anyone know of where I can get ahold of information on this device? From what I have gathered, it appears that the company has gone belly up awhile back which is probably why finding anything on this may require a little bit of digging...

Yeah, we started looking into equipment...it doesn't look like it will be cheap...I may just get out there with a shovel and start digging. Thanks for the forewarning and the reference though Tommy. Tim

Does anyone know of a good way to locate conduits around a substation? The instrument we have is one that ties to the neutral of the circuit you are tracing and sends out a radio signal. The problem with this method is that the neutral is tied to the ground grid at the substation and I...

Hi, I work for a small city owned utility and they are trying to rectify a problem where they don't have enough fiber between their sites for all the applications they would like to use. I, unfortunately, have been removed from this for awhile and would appreciate anyone's comments who has a...

Does anyone know of any resources available on the quad curve? We are commissioning some transmission relays...more specifically, the distance element of the relays. The fellow we had out here to test the settings had an Omicron test set that broke during testing so we are looking for...

Does anyone know of any good resources discussing protection schemes for a ring bus? Thanks, Tim

I posted this question in the motor forum, but may be more appropriate here... I was asked a question about which transformer design is best for a plant using large induction motors (no plug stop)...the largest is two 1250HP motors. The question was whether a circular-design power transformer...

These are installed in a plant substation separate from the plant, so I think we're okay there.

I was asked a question about which transformer design is best for a plant using large induction motors (no plug stop)...the largest is two 1250HP motors. The question was whether a circular-design power transformer or traditional rectangular design power transformer is best suited for this...

Sorry for the delay...wife and I just had our first baby so been a bit busy. Yes, the breaker is an oil circuit breaker, type fk-72.5-27000-10. David, your comment brought up something I didn't think about. When we were commissioning the transmission relays for this breaker, we didn't have...

One of our clients had a Trip Coil burn up on one of their GE 69kV Circuit Breakers. They found it after a fault had occured on the breaker's line, causing the breaker failure relay to trip the sub offline. The odd thing is that the prints for these breakers show them having two trip coils, so...

Thanks for all the input, it has been very helpful...

Thanks all-this is all very good information. I did want to clarify one point, however...whether a breaker or switch will be needed on each incoming line. So with the ring configuration, a basic layout may look like this: (Sorry for the bad dwg...not exactly Autocad quality) XF1...

Thanks David, that's a great point...I appreciate the input.

Thanks, I like that answer. Would your answer change if the incoming lines were 69kV instead of 138? We will be taking six feeders out of this substation. The client only has one other substation to date, covering about 40MVA of load, so this project is far overdue. One more question if you...

We are in the beginning stages of designing a 138 to 69kV substation on a greenfield site and would appreciate any input as to the design/layout. The substation is to be designed for an ultimate build-out of three 28MVA transformers, but will probably only see two of them ever installed. The...

Right. Sorry - the 13kV circuit is 750URD rated at 535 Amps and was pulling about 60 percent of that at the time of the fault. The 4kV circuit used 500kcmil cable, rated at 430 Amps. It is pulling around 80 percent.