MATHEMATICAL ANALYSIS OF WATER EFFECTS

[vanskat]

I am curious to see how we would mathematically treat the effects that water would have on current carrying conductors.

 

[electricpete]

Can you be more specific? Are you interested in quantifying unwanted conduction through insulating materials as a function of water content? What type of insulating materials? What type of equipment?

 

[vanskat]

Exaclty. I was thinking of quantifying conduction through insulating materials as a function of water content also. Well, type of equipment would be say, 50HP motor with #2 AWG Cu cable, standard insulation. Was curious about the general train of thought involved, a detailed approach if possible.( couple of eqns etc.)

 

[electricpete]

Tough question.

For what it's worth, there is a graph of insulation resistance for one generator both dry and wet at:

http://www.usbr.gov/power/data/fist/fist3~1/3~1_f2.htm

For older thermoplastic organic insulation systems (asphaltic), the insulation itself absorbs moisture which affects the bulk conductivity... so you have to consider both volume-leakage and surface leakage.

For newer thermosetting synthetic insulation (epoxy and polyester resins) systems, moisture does not much absorb into the bulk of the insulation, and surface leakage would be the primary effect (although the presence of any surface leakage during a dc test depends on the presence of a weakness in the bulk winding at some point... perhaps scarf joints in end winding area).

Sorry, that's just my thoughts, and not much to go on. Anyone else?