27th December 1996: "Voltage Gaming"

in the privatised electricity industry


Having become concerned about the persistently high voltages in my domestic single phase supply in Kensington in recent weeks, I passed on my concerns to the ACCC and the MFB Board Fire Investigation Unit.

The MFB Board was informed by fax on 19 December, 1996. My submission reached the ACCC (Melbourne office) on 20 December, and the Canberra office finally got it on 23 December. It has also been published on the Web, rather inacessible as a zipped Word 6 file but now available (since June 1999) as a hypertext document here.

Suddenly at 3:24 pm Eastern Daylight Time on 24th December , my domestic voltage took a dive by about 7 volts from 252 volts to 245 volts, and has stayed there day and night ever since. It does still go up a bit during odd times of the day though. It seems that whoever in Solaris is controlling the voltage has got wind of my concerns, and begun to take responsible action. Update: Solaris subsequently told me it was a coincidence, and I have no evidence to contradict what they said.) I believe they could easily shave off another 10 volts without any customer experiencing problems, but they would stand to lose millions of dollars in revenue:

A simple experiment (26 December 1996): I plugged 10 appliances into plugboards and measured AC current drain at various voltages, using an autotransformer. The appliances were chosen to represent the type of domestic equipment commonly left plugged in in "standby" mode (either intentionally or accidentally):

Current was measured using a cheap digital multimeter, which gives an unstable display due to the crude sampling method.

Results: 

	voltage        current(mA)        power consumption(watts)

	258                 475                         123
	245                 401                          98
	244                 396                          97
	238                 350                          83
	235                 340                          80

Discussion: These results show that this representative group of appliances do not act like a resistive load, and in fact their effective resistance (impedance) is the reverse of a normal lightglobe. A lightglobe's resistance actually increases slightly as voltage increases, so it has a limited capacity to self-regulate its power output. It will still have a shortened life at 250 volts though. The effective resistance of these appliances actually decreases as voltage increases, leading to a potentially unstable situation if too much heat is generated.

There is a much better way to do this experiment.

They would all run quite happily at 230 volts, but the problem is the distribution company would lose 33% of its revenue compared to forcing consumers to put up with the maximum "legal" voltage of 254.4 volts.

The NECA/NEMMCO application to the ACCC is conspicuously silent on the issue of voltage regulation, and in Victoria I have no evidence that the Regulator-General conducts any independent monitoring of supply voltages, possibly relying on Participants to keep operational records permanently in case they are needed for scrutiny. It is even possible that there is absolutely no recording or logging of voltages in LV circuits by any DistCo. It would be a pretty shameful record in my suburb if it were ever to see the light of day.

The industry in pursuit of the sale of more electrons, seems to have totally lost sight of the reason for the +/-6% voltage range from 240 volts:

The problem in unregulated LV lines is to maintain a workable, acceptable voltage to the last customer on the line during 99% of circumstances. This voltage is officially 225.6 volts, quite close to the old 230 volt standard of the SECV in the 1960s. I believe 99% of modern appliances will work just fine on 230 volts, in fact with more economic (if not electrical!) efficiency and with a longer lifespan than at 250 volts.

However both the former SECV and the privatised industries seem to have had no problem in allowing the voltage to remain so high, with the direct consequence, intentional or not, that they can sell more energy. Unloaded LV lines in the pre-dawn hours have until this week (first week of January 1997) been fed with over 250 volts. All sections of the electricity industry would appear to benefit from the increased "throughput" of the whole system resulting from increased customer voltage. The generation companies probably appreciate that they can just scrape through until dawn without having to desynchronise some of their units. Customers "safely" tucked up asleep in bed a 3am to 5am each morning should not have all their "gadget" appliances being subjected to the unnecessary stress and cost of a 250 volt supply. (June 1997 Update: get the latest info here).

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Michael Gunter................mickgg@suburbia.com.au............last update 26/06/1999