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LionelHutz, Interesting comment about VFD losses. I am working on 600 V, 250 HP Fan application but I never heard about losses being significant like you explained. Could you kindly elaborate why there are losses in a VFD case and not in a typical soft starter or DOL application. Thanks...

LionelHutz Thanks for your comments. Actually, as an engineer, I am just eager to find an answer. The issue is long resolved but I still want to find an answer. So, what was the Multilin P4 A doing when the cap. banks comes online and get the motor over compensated...which stopped happening...

Thanks all for your comments. I got a feedback from the site and they have resolved the issue. Just to recall the situation more correctly, Soft starter is feeding a 100 HP vent fan and after a little while when the capacitor will come on line, Multilin P4A relay will trip the breaker feeding...

I forgot to add one more aspect of Multilin P4 A relay "" Systems such as variable speed controllers may produce nonsinusoidal waveforms that may cause nuisance tripping of the single phase detection. If this is a problem, the single phase protection may be defeated by setting switch S305...

We have not checked that....But how relays being shorted can activate this relay to trip to current unbalance. Thanks

Hi... I am looking for a explanation in regards to this obsolte product P4 A relay from Multilin. A 225 a breaker is feeding two 100 HP fans with independent soft starters. The application is ventilation fans. The pitch of the fans has been changed, so they are not taking full 90 A as they...

Sorry about interjecting in to my own question, I found some thing on this link below on Page10 of 23 http://downloads.eatoncanada.ca/downloads/Low%20Voltage%20Circuit%20Breakers/Selection%20Guide/Series%20C%20MCCB%20Internal%20Accessories_s.pdf Here a shunt trip is represented as a...

Hi, I have done it quite a few times but now I have an application where I have to go into a bit of detail for specifying a circuit breaker. I know that if I have to operate a molded case breaker or for that matter any type of circuit breaker remotely or external means, I need a shunt trip...

Thanks everybody. I am dealing with AllenBradley and Toshiba on this issue. I guess there are few things I need to watch out as a consultant and solutions seems very traditional as well. Two important issues: 1. Voltage stress on Motor insulation 2. Noise I noticed that most of the vendors...

Hi,,, I am researching about the max. allowed cable length from VFD to motor. I spoke to one of the vendors application engineers and his answer was that max. what he has seen is 100 ft. My requirements are 400 m. I was wondering, is there a way instead of just relying on vendor, I can make a...

Hi.... I have asked few questions about this grounding grid and it is still on going. We have decided to use Eric Ground Enhancing Meterial on the periphery of the ground grid. The ground grid is in the middle of the rock. Excavated and backfilled with granular B. I am just wondering, to...

Thanks Lz. A manhole is a goood idea but how do I disconnect them. If I use a compression connector or a cad weld connection, it is a new headche when ever a independent measurement needs to be done. I read some where that Utilities have the leverage of using a switch but I am not sure about...

Hi, I was wondering about a practice followed by Utilities of using a disconnet switch to disconnet two grounding grids. I tried many vendors but no success.Could you kindly advise. I have two grounding grids, one of them is under construction and another is an existing remote grid. I want to...

Are you conducting fault at the line terminals of your generators ?

Thanks Jghrist. Your comments are like a picture and worth thousand words. I used WinIGs and my fault current is after considering a power flow analysis option which considers grid impendance as the fault impedance. My fault impedance is 24 ohms. I guess you cleared most of my doubts. I am...

Thanks Jghrist. The voltage is 44 KV that means L-N is 27 KV so this does not seems to be the issue.My GPR is with in theoretical limit. The local authority has completely rejected the idea of considering sky wire as a return path and is only considering a self sufficient grid to satisfy step...

Hi, I am not sure, if I am using a smart approach while trying to accomodate step and touch potential as it does not seems to be economical. My GPR is high approx. 18 KV. but local authority wants us to satisfy Step and touch potential issues. I have reduced the size of meshes to half, I gues...

I have a 225 A molded case thermal magnetic breaker. I beleive it is 80% rated that means it is 185 A continous rating. I have three fans 75HP, 75 HP and 65 HP at 600 V. The total ampacity FLA is 210 A. That means I am overloading this breaker. I am not sure, how this will effect the thermal...

So dpc, this measn ETAP defination of working distance is not correct. When I spoke to these ETAP people, they advised me to consider it as a distance between the pahse of bus bars.Here is a clip from there help file: " Working Distance " This group provides information about...

Thanks All for your such a quick response. DPC you mentioned about the distance if greater than 18" I better be have a good reason. My situation is a 13.8 KV switchgear. And I had an impression this distance relates to the distance between the phases of BUS BARS. This is what ETAP considers. So...