Lightninarrester
Member
I am trying to calculate voltage drop on 13.8kv cable. I am using Vd=1.73xIxDxRf, however NEC chapter 9 table 8 lists the Rf for 600V cables only, what would be the Rf value for like 15kV cables? Thanks
Voltage Drop
- Thread starter Lightninarrester
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physis
Senior Member
Re: Voltage Drop
Isn't the voltage rating an insulation parameter? If you're talking about the same size conductors, 600v. versus 15kv. I wouldn't think there'd be much difference in resistance between the two. I never use 15kv conductors though, there might be something I'm not aware of about it.
Isn't the voltage rating an insulation parameter? If you're talking about the same size conductors, 600v. versus 15kv. I wouldn't think there'd be much difference in resistance between the two. I never use 15kv conductors though, there might be something I'm not aware of about it.
rcwilson
Senior Member
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Re: Voltage Drop
Check the Okonite website technical section. Southwire and Anixter also have similar information.
At 15 kV, the wider conductor center to center spacing caused by the thicker insulation makes the inductive reactance higher than the typical 600 V circuit. You may need to account for this reactance, the AC resistance and the load power factor to get a good voltage drop calculation.
http://www.okonite.com/engineering/index.html
Check the Okonite website technical section. Southwire and Anixter also have similar information.
At 15 kV, the wider conductor center to center spacing caused by the thicker insulation makes the inductive reactance higher than the typical 600 V circuit. You may need to account for this reactance, the AC resistance and the load power factor to get a good voltage drop calculation.
http://www.okonite.com/engineering/index.html
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