Guys,
ETAP SC report has Symm KA rms and Adj. Sym KA rms and it uses M.F which,
Adj. Sym KA rms = M.F. x (Sym KA rms)
I am wondering how ETAP calculates M.F. ?
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Guys,
I have an ATS data sheet and wondering what is 100KA? Is this the current that ATS can stand (not interrupt) for no more than 0.05 second?
An investment in knowledge pays the best interest (Benjamin Franklin).
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Guys,
Is there any way to tell how long it is going to take for an induction motor to start?
I know there are thermal and other curves for motors but I don't know if any of them tells the starting time of the motor ...
An investment in knowledge pays the best interest (Benjamin Franklin)...
Guys,
What is your suggestion for decreasing the touch potential on the pump room (lower right)?
I have 4 ground rods (one in each corner of the the room) and it still shows a high touch potential.
I have added lots of copper and rods on other parts of the grid and adding more, looks a little...
Guys,
I am trying to connect the grounding conductors in tray to the ground grid in CDEGS but because of different elevations (and may be different environment (soil and air)) I can't connect the conductors.
Am I missing something or CDEGS only models underground conductors?
An investment...
Guys,
For ground cable sizing of MV services, should I use Table 250.122 of NEC?
An investment in knowledge pays the best interest (Benjamin Franklin).
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Guys,
I have a main transformer with the rating of 12/16/20MVA (KNAN/KNAF1/KNAF2).
My final load list shows 14MVA now. I know this transformer can handle that but how bad is to have normal running loads more than the base rating of transformer? (in my case 14MVA which is more than 12MVA)...
Guys, my understanding is if we have one CT around all 3 phases (to measure the residue), ANSI calls this as Zero sequence or G(round) CT and if we have one CT around neutral wire, ANSI calls it N(eutral) CT.
If the above statement is correct, what are the applications of each?
Guys,
I am trying to protect the following pipe against lightning. What is your suggestion?
1- To put air terminals every 50ft along the pipe
2- Using static mast at both ends of the pipe and running a wire along the pipe?
3- Any other suggestion?
Hi Guys,
Running a short circuit on UPS system, I noticed short circuit current in UPS output is much less than SC current in input.
Am I missing something or it is always the case?
Guys,
I have 3 motors (200 hp, 2 hp, 5 hp) in a service and I want to size the main circuit breaker for this service.
Articles 430.31-44 of NFPA talk about overload protection and 430.51-58 talk about short circuit protection.
If I want to size a Molded Case Circuit breaker for this service...
Guys,
Do you know how to calculate MF in Momentary Duty? (I think MF is used to account for DC component of SC and to get the Asymmetrical value from Symmetrical momentary short circuit value.)
Guys,
I used to study load flow with normal voltage level for utility and define several scenarios in distribution level such as loosing an MCC etc.
I was looking at another study that has only 3 scenarios with 95%, 100% and 105% voltage levels for utility and nothing in distribution level...
Guys,
I have 26 KA ground fault to be taken care by ground grid. I have put so much copper and rods but it doesn't change that much. Should I put ground well or anything else?
Any help would be appreciated,
Guys,
I have two soundings from field (perpendicular to each other) and each of them gives one soil model for designing grounding grid.
I designed my grid based on first Grid and made sure it works for the second soil model too. Do you think this is a good approach or I should combine the data...
Guys,
for a 2LG fault in phase A and B, fault current flowing to the ground should be calculated as:
Ifground=IfA+IfB.
I have IfA and IfB separately from utility but, summing them up, gives a (smaller) number which is not matching ETAP.
Is this because ETAP only gets single and 3phase short...
Guys,
We usually use HRG for LV networks which limits the grounding resistor current to 5A-25A.
If we take a 3A charging current into account, all ground grid can see in LV network is 25A+3A=28A ?!
This number looks low for designing a ground grid but it is all can flow through ground path right?
Guys,
I have to change the old gear in the following system and design the grounding system for that.
Problem is that the old system is not grounded and I can not touch the old T1.
Any idea for grounding the new system? Adding new 2MVA transformer looks an expensive option!
