ELECTRICAL SUPPLY

Dominion, Volume 20, Issue 60, 4 December 1926, Page 11

ELECTRICAL SUPPLY

CORRECT VOLTAGE IMPORTANT ADVICE BY CHIEF ELECTRICAL ENGINEER The chief electrical engineer of the hydro-electnc branch of the Public Works Department (Mr. F. T. M. Kissell) has issued a memorandum stresstug the necessity, if electricity is to become popular with consumers, that satisfactory supplies should be provided and maintained. “With the increasing number ot. electric lighting, cooking, and heating installations throughout the Dominion,” he states, "the question of correct voltage of supply is becoming more important, and I regret to say that in some cases the results of electric service are not always satisfactory from the consumer’s point of view. This can < be attributed very largely to excessive voltage drop on distribution lines, or the inadequate size of wires installed on the premises causing too great a voltage drop between the supply system and the apparatus in use “Electric lighting and heating appliances are particularly sensitive to low voltage, and if the distribution lines, or interior wiring, as the case may be, are inadequate, the popularity and universal use of electricity for these purposes is likely to be seriously jeopardised thereby. “Every current-consuming appliance on the market to-day, whether it be an incandescent lamp, motor, range, or water heater, is designed to give its maximum efficiency at a specified voltage. and variation beyond the recognised voltage limits interferes with the efficient operation of the appliance. “A tradesman or firm selling any commodity which is ‘light weight 1 incurs the penalty of the law for defrauding the customer, and low voltage can be deemed to be in the same category as ‘light weight’ goods. The consumer is paying for electrical supply at a specified voltage, and this supply should be up to the required standard. The ‘quality’ is directly dependent upon voltage regulation, and electrical energy loses its value as a commodity when variations in voltage exceed certain limits. These limits are already well-known to every electric supply authority. "In connection with the effect of voltage variation on incandescent lamps, it can be shown that if the voltage drops 11 per cent a 50 c.p. lamp will onlv give as much light as a 33 c.p. lamp with its full rated voltage, and furthermore, the 50 c.p. lamp will consume 27 per cent, more power than the 32 c.p. lamp for the same amount of illumination.

Effects of Low Voltage. “As regards the effects of low voltage on heating apparatus, such as ranges hot-water systems, radiators, etc., toe power consumption does not vary directly as the applied voltage, but as the square of the applied voltage, and the outstanding result, of this makes itself very evident in the longer time taken to perform cooking duty. Curves have been prepared to co-ordinate the relationship between voltage variation and time taken in cooking, and these show the following results:— "A 5 per cent decrease in voltage increases die heating time by 10 per cent and period of cooking by 12 per cent. “A 10 per cent, decrease in voltage increases the heating time by 25 per cent and period of cooking by 30 per cent.

"A 20 per cent, decrease in voltage increases the heating time by 55 per cent and period of cooking by 70 per cent. “As an example, consider the case of a 1500-watt element in a stove and the normal cooking time as 30 minutes. The energy consumption at full voltage would thus be 750 watt hours. With voltage 10 per cent, low, the time is correspondingly increased to 39 minutes, and the energy consumption to 789 watt hours, which is clearly a case of the consumer being illegally charged for extra energy due to the supply authority’s voltage being below standard.

"High voltage is also detrimental to electric supply, but its prevalence is not so great as to require more than this passing reference to its effects.

Investigation Warranted. “The existing conditions as regards voltage of supply on consumers’ premises appear to warrant some investigation. as instances are suspected where low voltage is being supplied, and it is felt that some licensees are not fully alive to this phase of the electric supply business. One of the fundamental conditions of all licensees is that a satisfactory supply must be given to consumers, and in the interests of electric supply in general, it is desired that supply authorities make it a practice to look carefully into the question of the suitability of the wiring on premises before connecting up heating loads, and if complaints are being received from consumers already wired up, it is hoped that they will promptly ascertain and remove the cause of same.

"In conclusion, I hope thaj as a result of hav ng directed attention to this matter, all electric supply authorities will assist by keeping abreast of the demand, and at the same time continue to render th ■ service to which all consumers are entitled."