Shield Voltage Calculation for 25kV

[cherry2000]

I wanted to know if anybody has carried out calculations for a. Floating voltage b. Circulating current & c.Shield loss per unit length...for 25kV, 3C, cable with core shields ungrounded at one end / grounded at both ends. Interestingly, some relevant sections in IEEE 525-2007 have been removed and there is not much to fall back on.

 

[alehman]

Okonite has an article about this on their web site.

http://www.okonite.com/engineering/shielding.html

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[7anoter4]

According to EPRI EL-5036 Power Plant Electrical Reference Series, Vol. 4, “Wire and Cable”
ch. Shield Impedances.
Xm=2*Pi()*F*(0.1404*LOG10(S/rm)) micro OHM/ft
Let's take a 25 kV 3*500 MCM copper conductor cable [Okonite]

http://www.okonite.com/Product_Catalog/section2/section2-pdfs/2-25.pdf

S=1.48 in. rm=1.49/2 F=60 Irated=600 A [in air 40oC] 1000 ft length
Xm=16.09 /10^6 ohm/ft
Induced voltage= Irated*Xm=0.0096523 V/ft 9.65 volt/1000 ft

 

[cherry2000]

Thanks alehman & 7anoter4..I shall go through the literature and let you know what I get..Thanks again!