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Hello ALL, This question is succession to my earlier question regarding reclosing. I appreciate the input. On my 27 kV system, station bus has a fault 3 ph fault of 631 MVA, approx. 13000 A. The feede is a mix of O/H and U/G, run of 6000 m. Fault at customer main incoming primary 27 kV...

Hi All, I am programming a GE relay for a new feeder in a 27 kV station. feeder length is approx. 7 miles. Approx. 3 miles of feeder length is underground cable and rest is overhead line. Is there a thumb rule that can advise for this feeder not to have reclosing because approx. 50% of...

After reading replies to these posts, I wonder how come my utility has a 115 kV/27.6 kV system grounding with a 1.5 ohm resistor on the secondary side and then coming out of staton 27.6 kV, an O/H 27.6 kV feeder supplies pole top distribution transformers and I think may be they are single phase...

Hello, "I aplogize for not being very much specific in the information here." I need some input into understanding my responsibility as an engineer and vendors responsibility who is supplying the equipment. I am planning to buy a arc rated switchgear for a "X kV" voltage. For testing...

Hello All, I am buying a 4.16 KV swgr fed by two incoming XFRM's rated 5 MVA, 27.6 kV/4.16 kV. Both will operate in parallel with no tie. Voltage= 4.16 kV TR1= 5 MVA %Z1= 5 TR2= 5 MVA %Z2=5 Short Circuit Contribution MVA(TR1)= 20 P.U.=13895 A Short Circuit Contribution MVA(TR2)=...

ohagan... I have used WinIGS and there are few things this software interprets Neutral and Ground.. in a different fashion... u can send ur model to Sakis and analyze this on the phone with him... I have done it few times and he was very helpful.... besides that there are grounding gurus...

Hello, I have done my homework well before asking this questions and also read posts here as well. Because, I am not an expert so need your final opinion, Q#1 Why in most of the cases, we d'nt consider DC offset value of current in to calculation when the whole point of calculating...

Thanks Alehman. I just have to pick up pieces of some body who did not do a diligent job picking up the XFRM size in the past. I am sure, studying trip units again will give me a better handle on the situation. I was probably cutting corner by asking trip question. I have done a quite a bit of...

Thanks Alehman. I apologize for lacking clarity in my question. Yes there are two sources, which will feed same panel in case of transfer. 1. Use of Molded Case CB- Eaton has MCCB up to 2500 A, Based on your experince a Power circuit breaker should be a the way to go. Would that not be more...

Hello, I truly beleive in" If you dont use it you loose it". For the last one year, I have started working for a utility and working on 27.6 kV and onwards, I completely forgot how to set a molded case circuit breaker, which I used to know everything about. 120/208 V panels are the last thing...

Auslee, Sorry for jumping in your post. Thanks for your response Jghrist and EddyWirbelstrom. 1. In Stations those have a Delta secondary or a floating star connected secondary leaving the station and then a fault occurs down the line, and if there is no ground return, Line breaks and hands...

I have a questions for the experts here. Suppose the primary is 115 kV Delta and Secondary is 44 kV with solidly grounded star connection. Three O/H line leave the station with a ground underneath the three wires and no neutral. Dont you think in that case if a fault occurs 1 KM down the line...

Bravo RCWilson, You had me for a sec. while I was reading this post and I said to my self How you can come to 37.5 kV but you infact were alluding to the misnomer. I actually myself learned grounding from this post. You and Jghrist had contribution towards it. I recall reading your posts...

Thanks Steven

Hi, I had posted a similar post in the past as well. Unfortunately, I have not been able to find proper litrature issue on this subject. I am sure, some of you have come across this and will be able to advise me some useful input. 1. Partial discharge or Corona test= Is this traditionally a...

Actually, I was involved in some thing similar few years ago, the project never went to construction but design was almost complete. It was a trailer park where all O/H lines were tapped to new pad mounted transformers. All lateral tap had fusing (fuse cut-out with arrester). We ordered pad...

Jghrist, "There will seldom be critical step- or touch-voltages around a slab foundation, so high accuracy is not usually important." I have learned grounding by reading your posts here and they have been excellent. Some how the above phrase is not getting to me. Let me see if I got it right...

You should speak to Dr. George or Dr. Sakis at Univ. of Atlant(Georgia Institute of Technology), they own the company that sells these softwares. They are very good at responding emails.

Tal is a setting normally on the high vol. side of the transformer to increase or reduce the voltage.

Thanks Small greek. This is actually a 38 kv Class vacuum inter. technology breaker. Please correct me in the following observations if I got them wrong. 1. Vendors do motion tests as part of design test. 2. I had an impressions that there has to be a contact point on the front of breaker...