Voltage drop variation between cable types

[erictran88]

Hello, I am an intern at Computer Science Corporation, specifcally, the power engineering group. I have been tasked with designing a voltage drop calculator, I know there is a free one on the site but I have been given specific cable types to use. The calculator specifies only Stranded Copper Coated and Uncoated. I was wondering if that would apply to cable types: LSTSGU, LSTSGA, LSFSGU, LSFSGA, LSDSGU, LSDSGA. Also, is there data out there about their impedance, resistance, and reactance per foot? Where can I find this data? Would this data make my voltage drop calcs more accurate versus the calculator on this site (it uses a general K = 10.8 value for copper)?

Any help would be greatly appreciated. Thanks.

 

[winnie]

_Every_ aspect of the cable will alter its impedance and thus its voltage drop. Your job is to figure out what aspects are actually most relevant, and to also do enough of an error analysis to understand just how accurate any calculator could be.

Spacing of conductors will alter the magnetic properties and thus the inductance.

The insulation will respond to the changing electric field and introduce its own impedance.

Hell, even the composition of the air around the cable will have some small effect.

But all of these things are tiny as compared to the major factors:

1) Composition of conductors. Are they aluminium or copper, and are there any other metals involved as coatings?

2) Temperature of conductors. The resistance of the conductor will change by a considerable margin over the range of use temperatures. The 'K' factor of 10.8 is only at one particular temperature. Also remember that conductors heat themselves up in use.

3) Manufacturing variability in the size of conductors.

4) Magnetic properties of any armor or conduit.

Good luck. The above is my off the cuff answer; you will need to research the details!

-Jon

 

[erictran88]

Thanks

Thanks

Thanks for replying. Yeah I realized I needed to do some more research. Luckily I found Mil Handbook 299. Solved all my problems.