Recent content by PTCruiser85

Gentleman, Thanks for introspection. Why would a vendor publish a 3 sec withstand rating anyways when the momentary withstand is already hight with asymmetrical current. Could it be because momentray withstand Asymmetrical rms value for 1/2 cyle cannot be sustained by the breaker that long...

Thanks Gentleman. Appreciate the information. Could you also advise, if this value is normally specified in Symmetrical Amps or Asymmetrical rms Amps. I think it should be Symmetrical value as by the time elapses to 1 0r 3 sec The fault current is symmetrical anyways rather it becomes after 5...

Gentleman, When we specify a medium voltage circuit breaker, there are certain short circuit ratings that are part of the spec: This is what my understanding is and please correct me if I am wrong: 1. Interupting Rating(break capacity)- Symmetrical RMS 2. Close and Latch(Make...

Thanks Cranky 108. Your comments are very useful. 1)Could you kindlly advise, how to quantify damage on cables and equipment for the fault level. 2) SEL 50 means SEL 501. I had an impressions that all digital relays has a algorithm that filters out that DC component and activates only when...

Bravo CraNKY108 ! You said what the reality of the problem is. I have been trying to find a real solution to this problem for a month now and unfortunately people in utilities dont tend to change anything and want to come up with a solution without understanding real issue. When I came across...

Thanks jghrist. This is what I was looking for. I was advised by one of the leading relay vendor application engineers probably wanted to market their relay. I was told that I can use the load encroachment function and differentiate between fault and load and now if I think it does not make...

Gentleman, Thanks for your comments ! I guess my question steered the discussion in a direction which I am not familiar with actually. I was trying to find out that in situation as I discussed earlier in my pervious post where fault on the customer that is close to the substation is approx...

Hi, I had asked a similar question in the past regarding a coordination study where the distance between fault location and feeder was only 700 m. It was very difficult to coordinate. this forum had some interesting contribution in terms of views from you guys. After doing some more research...

Thanks jghrist. My objective of asking this question to get an introspection in to repercussions of fault current flowing for a certain period of time Should I presume that a voltage drop of .5 sec can take down computers motors and lot of other nuisance stuff. As soon as power will be...

Thanks dpc. I appreciate the recommendation. Could you still advise the practical(historical & statical ) impact of fault current flow for .5 sec and the cable fault capability question in my post.

Thanks for your reply davidbeach. It is an actual underground cable feeder fed right from the substation breaker and this feeder have other customers as I have been told. Could you kindly reply other part of my (1,2) questions in the above post as well. Thanks

Thanks Gentleman. I am glad to seek advise from people who know it the best. But I have still have some confusion and need your advise. Utility is supplying us with a cable feeder and they dont use reclosing on U/G cable feeds. As I recall they have have seprate old individual Inst O/C and TOC...

Hi All, This is my first time and have seen some similar posts like my question. My feeder is 1.5 km from utility and the fault level at that point and my feeder is approx. same and some how my fuse cannot coordinate with their instantenous overcurrent protection. Could you advise me how a...