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One other observation I had on several large scale renewable projects (BESS, Wind) is that on the 34.5kV collector system feeders from HV substation out Wind/BESS modules had both a concentric neutral as well as separate equipment ground conductor (typically #2AWG). Have others found that to...

After looking into this a bit further I believe I've found some better understanding to my above questions. From what I can see, anything inside of a HV substation yard that has a ground grid utilizes the ground grid for ground fault current between fault location and source in substation (or...

I know that the NEC requires additional Equipment Ground Conductors (ECG's) to be run with any feeders between equipment and Supply Side Bonding Conductors (SSBJ) to be run between transformers of separately derived system and downstream equipment. My question is in a HV substation environment...

I’m looking at a project where customer is looking to install temp 138kv-34.5kv transformer in existing substation in order to repair existing transformer. Plan is to locate tramp transformer in separate location in yard and reconnect HV and MV bushings to existing buses work to minimize...

I've never quite gotten my head around the concept of "GPR". Is GPR the voltage difference between equipment in substation and local earth, equipment to remote earth, or difference between local and remote earth. If someone has a basic example, they can share to help solidify I'm sure that will...

I know that for applying a PT on a 4.16kV impedance grounded system (non-rigidly grounded)the PT needs to be a 2400/4160Y PT as opposed to a 2400/4160GY PT due to the fact that the neutral bushing needs to be a fully rated bushing for when neutral floats to line voltage during certain fault...

@wcaseyharman For detection of utility side faults would the PT's for volage detection need to be on the utility side or could they be on the gen side of transformer (delta side)? Would PT's need to be connected in wye-gnd/wye-gnd config or would this be wye-gnd/broken delta for use with 59N...

In looking at this application a bit further I'm not certain that I need the new 24.7kV high side recloser that I have shown on one-line. In looking at most distributed generation applications connected to utility distribution I found that there is only a breaker on low side (DG side) of...

What about a situation when the existing recloser detects loss of utility, utility fault, or collector circuit fault and opens thus leaving the generation collector circuit ungrounded until wind turbines are shut down. Assuming that each turbine has a step-up transformer to 12kV with delta side...

For some reason SLD didn't attach to previous post so trying again here. https://files.engineering.com/getfile.aspx?folder=a6db0ec2-587f-48b5-9a28-4039659e4351&file=One-Line.pdf

Attached is SLD. The black is what is currently there today and the red is what is being added for transformation to 25.9kV. I Appreciate any feedback. @protoslash thanks for your explanation on purpose of grounding transformer, that makes sense now.

What about if the interconnecting transformer is a wye-gnd / wye-gnd transformer that will allow zero sequence current to pass. Does it matter in that case weather the system grounding transformer is on generation side or utility side of transformer? I'd assume it needs to be on generation...

Apologies, yes I meant to say a Grounded wye-Delta where wye side is connected to line and ground. Delta side however is a closed delta configuration not broken. This is typically just a conventional transformer that can used as a grounding transformer.

In relation to my other recent post I'm looking at an application where there are (3) 3MW wind turbines connected to a 12.47kV collector feeder before interconnecting to a 12.47kV distribution line (there is actually a voltage regular between turbines and utility line to bring 12kV turbine...

Is it possible to implement transformer differential protection using (2) reclosers on high and low side of transformer? Looking at application where existing 15kV recloser would be on low voltage side of new 15MVA transform and consideration adding new 25MVA recloser on 25kV high side for...

Waross Thanks for your response that is helpful. So if I'm understanding correctly in this application with wind generators if the line voltage is fluctuating and the generator can keep up with matching, then unintended reactive power VARS will flow back and forth between gen and line...

Thanks for responses. @waross - Is it common for distributed generation to not have voltage control? Or are they typically set to Var control or similar? Even without voltage control wouldn’t they just take on the voltage of distribution line (grid) voltage? If existing voltage regulators are...

I'm looking at an application for a distributed generation wind site that currently has about 12MW of wind generation at 12kV that goes through collector system and step voltage regulator before interconnection point of 12.47kV utility distribution line (recloser and metering at interconnection...

@kiribanda Are the surge arrestors you recommend the ones that would be on the transformer itself? Are the 345kV switches you are suggesting part of GIS or separate 345kV air switches outside of GIS on feeders? Is purpose for these switches to be able to isolate GIS without having to rely on...

Thanks for all the great responses here. I've attached a very basic layout sketch which shows the scale of GIS lineup (from vendor) as well as the (4) feeder transformers. The 240MVA transformers are quite large so layout pretty wide compared to the GIS footprint. Ideally I was trying to...