ECN Forum Forums General Topics of the Trade General Discussion Area S.W.E.R.

that's worse...

That reminds me of a photo I saw of a pole in some poor part of India where people regularly added their own unofficial drops to the lines.

At least this one looks as though they're being metered for it, but it sure leaves something to be desired.

I believe that particular pole was found somewhere in the Caribbean. (Arc picture entry about halfway above revised with historical info/corporate memory.)

OMG, if someone doesnt pay their bill how do they know which one to red-tag ?

I went to Venezuela a long time ago and that was exactly what I saw and the customer did his own hookups right through any open window or hole in the wall.

but electric I thought I wasn't caculating it right as I was trying to figure the voltage drop then multiply divide it into the primary voltage. too late in the evening

[This message has been edited by hurk27 (edited 05-30-2002).]

Re the probable losses in transmission, I've sat down and re-read the whole Canterbury University article in detail.

They mentioned a 25A limit on an SWER feeder. Given that the highest quoted voltage is 19.1kV (one leg of a 33kV 3-ph system) that works out to a maximum loading of approx. 477kVA (they quote 500kVA, but who's arguing? ).

Given an overall ground resistance of 5 ohms that was quoted above, the loss would be 3125 watts, or less than 0.75% of the power being transmitted. Here are some quick figures for other ground resistance values:

10 ohms, 6.25kW, 1.3%
25 ohms, 15.6kW, 3.3%
50 ohms, 31.2kW, 6.5%
100 ohms, 62.5kW, 13.1%
250 ohms, 156kW, 32.7%

That's at full load, of course. At 25% loading (119.375kW, 6.25A) the figures are more reasonable even at high resistance values:

5 ohms, 195W, 0.16%
10 ohms, 391W, 0.33%
25 ohms, 977W, 0.82%
50 ohms, 1953W, 1.64%
100 ohms, 3.9kW, 3.3%
250 ohms, 9.8kW, 8.2%

An umetered loss, a loss to the poco...

True.... But I bet they allow for it in setting their rates, just as they would allow for losses on a Cu/Al line, in xfmrs, etc.

For a 3%-impedance pole transformer, the load loss is {surprise} ~3% at rated.

You bet utilities allow for distribution lossses in their rates.

Really though, without having a peer-reviewed paper on the matter, aren't we all taking pot shots at the real numbers?


[This message has been edited by Bjarney (edited 05-31-2002).]

You're probably right -- Some actual figures from SWER systems already in use would be good.

But however low that ground resistance, I still wouldn't wanna be near a rod that goes straight to a 19.1kV source through a xfmr.