Search results for query: *

Thanks for your input. Fig.1, pic#3, shows switch open during saturation, which is not correct, it should be shorted out during high excitation. am I missing something in your response ?

Hi I have gone through the article below and I am not sure if I have it wrong or article has the other way round. http://www.idc-online.com/technical_references/pdfs/electrical_engineering/current_transformer_concepts.pdf On Page 2 of pdf, It says in low excitation, Im > Ib and other two...

Hello All, I asked a consultant to do a arc flash study on a 1600 A 120/208 switchboard. Unit has molded case circuit breakers with Schneider Micrologic 6.0 P trip unit. i need some input in testing these breakers for commissioning using primary injection. I will not be testing it myself but...

Thanks MKFPE. Please see the attached schematic. What do you think, would this work.http://files.engineering.com/getfile.aspx?folder=a8bf6750-4133-4e8d-ba33-c88ca030fff0&file=Grounding_Description_New4kv_Switchgear.pdf

Waross, Does the size of grounding bus would make a difference of the switchgear if concentric neutral are to be bonded, Do we have to size grounding bus like we size neutral. Appreciate your input.

Thanks Waross. XFMR output based on 5 MVA is approx. 700 A. There are three outgoing feeders each fed from a 1200 Amp breaker. So in nutshell this is how it works. Please let me know if I got it right. Feeder #1: Three single conductor 4.16 kV 3X 1C, 500 MCM URD concentric neutral have their...

Hello All, My application involves a 5 MVA 27.6 kv/4.16 kV Primary Delta and Secondary is star solidly grounded transformer. A 4.16 kV switchgear is fed from the secondary and I have been told by my utility standard guys that the practice of connecting outgoing feeder cables is as following...

I have something to share about Mr. Zocholl. It was last year, I had a question about one his articles and I contacted SEL. He has not been working for SEL for a while but SEL tech support discussed my question with him and he called from his home in my office and gave me his number if I have...

I also browsed Blackburn book but it jumps to application directly and I guess that was not much help. I would still appreciate answer to question #1, if somebody might know. Liteyear, Appreciate your input. I went further and studied the interaction of Current-Voltage relationship within...

I have been working on basic feeder protection for a while now and recently started focusing on concepts of directional over-current protection and distance protection. It seems like I am missing some conceptual background to get a handle on these topics. Here is what I would like to start...

If that would have been possible then my life would be easy. As you know u bump into some people who don't try to understand logic. That is why I had to do something like this.

Thanks Mgrtp for the write up. Actually utility is using RXMH2 relay to trip my breaker. I will be using tripping assembly to be activated by this relay. It has a time delay dial on RXKL Relay to delay contact dropping after deenergigation. I will have to ask my P&C Staff to use DIN rail...

http://www05.abb.com/global/scot/scot296.nsf/veritydisplay/367d9ea1fbbcf1e1c12573300072e4e9/$file/1MRK508015-BEN_B_en_Auxiliary__signalling_and_trippning_relays_RXMA_1_RXMA_2_RXMS_1_RXSF_1_RXME_1_RXME_18_RXMH_2___RXM.pdf Above link shows a tripping assembly marketed by ABB. The schematic is...

Thanks to All. Appreciat the comments. I think I will go with interposing relay option. I am trying to find interposin relay with very short operating time and which is used for breaker tripping interposing operation. I have looked at ABB RXMS1 but it canot break enough current. Any suggestions...

Thanks Mgtrp. I just have tweaked to reflect my situation. As the right side is auxiliary trip. Please see attached. It is a 125 V DC system, Could you please suggest me something on Diode specifications. I was advised by one of my peers that it might be good idea to have a resistor in...

Is it acceptable practice to have a current operated relay in series with a trip circuit ?

Thanks Main relay is a SEL 351 and Aux. relays from transmission utility are old electro-mechanical relays. mgtrp, I like your idea of using a diode, could you please be kind enough to draw a schematic and show it to me. Thanks

Hi, This might be more of a controls related question. I have attached a pictures which has two schematic. 1. Existing Schematic 2. Planned Schematic My Distribution utility shares substation with the transmission utility. Bus protection and bus is owned by transmission utility but our...

What do you mean protections tests ? Look at the GE literature and it will mention everything you need to know.

Thanks Liteyear, I appreciate the effort. I still did not get it.Something is missing for sure. Hopefully somebody can give more explanation.