waross (Electrical)22 Oct 24 16:33
Is the meter showing the energization current of a transformer? One phase is often subject to DC offset and that may be almost as much as 2 times the other phase peaks.
I looked and did not see anywhere the meter may be showing energization current of Xfmr...
bacon4life (Electrical)22 Oct 24 16:12
Do you have reason to think the loads are balanced across phases? Perhaps there is twice as much load connected to B phase?
Do you think its possibly due to imbalanced loads? The value is approximately 50 Amp peak in phases A & C but 100 in phase B...
Hello All,
I have a question. I have a meter that is showing the peak current in phase B to be double that of peak current phase A & C. Does anyone know what may cause this? In phase B its 190 Amps approximately while in A * C the peak was about 95.
I know how many power cables I need based on Xfmr size and LV cable I plan to use. My question is do I need a ground and neutral? My thinking is 216 is line to line voltage but the 125 would be line to neutral so I would need a neutral and a ground. Is this correct?
What do these terms mean in this type of switch?
Load Break? Does that simply mean it can be operated under load?
Air Switch? Does that mean that it doesnt have any special insulation such as SF6 etc.? Just operates in atmosphere?
waross (Electrical)22 Jan 24 23:41
Equipment grounding or bonding conductor apart from system grounding conductor.
Different rules, different sizing.
I think what you are saying to Equipment grounding is same as bonding conductor? and the system grounding conductor is what would be the ground...
dpc (Electrical)23 Jan 24 01:36
In the NEC, a grounded conductor carries load current (neutral) while an equipment grounding conductor normally carries no current.
So in this case wouldn't the ground cable carry neutral current back to ground? and also carry current under fault conditions that...
Ground cable size required for MV circuit
I am currently designing a power system to use 3 1/C 500 kcmil MV cables. I am doing a calculation to determine the size of conduit required as well as grounding cable size required.
I found thread on forum listed here about grounding cable size...
As with many things, the definition of over-current has changed over the years.
But, cable ampacity, 125% of rated current.
The protection setting, by code, depends on a number of factors:
Transformer voltage,
Transformer %impedance.
Fuses, breakers, dual element fuses,
Overload protection on...
waross (Electrical)29 Dec 23 17:14
Conductor size is based on rated full load current.
If there is a possibility that an ONAN transformer may be upgraded by the addition of fans, the AHJ may require the ONAFfull load current to be used.
It comes down to the conductor size or ampacity must be...
waross (Electrical)
Noted
Finally sit down and was able to review above equations to fully understand. Your feedback is appreciated.
Quetiosn:
What locale code are you referring to above? My location we would be required to use NEC Article 450 for determining Xfmr protections and while the...
b_gibb (Electrical)29 Nov 23 15:48
The cable is sized for the protection, not the transformer full load rating. For example, if your fuse is 30A, you need to size the cables for this value.
In other words, calculate the protection first, then the cable size.
Should'nt the cable be sized larger...