AC CABLE SIZING
AC CABLE SIZING
(OP)
How to size the cable for the data given below:
Considered Cable = 70 mm2
Route Length = 110 m
Load Current = 57.27A
Voltage = 110 VDC
Considered Cable = 70 mm2
Route Length = 110 m
Load Current = 57.27A
Voltage = 110 VDC






RE: AC CABLE SIZING
Protective device?
Disconnection time?
Acceptable volt-drop?
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RE: AC CABLE SIZING
RE: AC CABLE SIZING
Step 2: from tables check voltage drop and increase the cable size if necessary.
Bill
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Jimmy Carter
RE: AC CABLE SIZING
Title suppose to be DC CABLE SIZING, I am suppose to edit the title but I don't see a tab to edit the said title.
Type of Cable = XLPE
No. of Core = 2 cores
Acceptable VD = 3%
Type of Installation = Installed in Air (ladder)
Now, is 70mm2 cable is sufficient to handle a load with a current given (57.27A)?
Thanks
RE: AC CABLE SIZING
2) Voltage drop - Assuming stranded, plain copper, the max dc resistance of a 70mm2 conductor is approx. 0.268 Ohms/km. Therefore, the voltage drop over 110m is Vd = 2 x 57.27 x 0.268 x 110 / 1000 = 3.377Vdc, which is a voltage drop of 3.07%. So it fails the voltage drop criteria.
3) Short circuit temperature rise - probably won't be a problem unless there's a high dc fault capability. In any case, you need to know the protective device type, rating, tripping characteristics / disconnect time, fault let-through energy, etc and the maximum dc fault current.
RE: AC CABLE SIZING
You also need to look at the protection for the circuit to ensure that it is suitable first. The cable size is then based on the protective device and not the load.
Is it 2 core 70mm2 or 2 single cores. I haven't ever come across 2 core 70mm2 cable before and I would think it is expensive.
All this information regarding current carrying capacity voltage drop should be on the cable datasheet.
Anixter have a great cable handbook if you ask your local rep for it.
Here is the 600/1000V XLPE single core informatin from it,
http://onl
Assuming that it is 2 single cores installed on cable tray.
Current carrying capacity is 310A, though you wil neet to derate for , ambient conditions, no of conductors in the vicinity , Installation method etc.
You then need to compare that to your protective device. If the upstream device will let 300A flow in the cable then it unlikely to be sufficent. I souwl suggest that something inthe 63A range might be a good place to start
Volt drop is .68V/Am so for you is 111m x 58A x .68V/Am = V
I'll let you do that bit yourself
RE: AC CABLE SIZING
In your case, calculate the total derating factor for the cable. It depends upon the method of installation and the enviroment.