Remarks.—Copper loss increases with temperature because the resistance of the metal rises. Do not overload the current coil of the wattmeter. For greater accuracy the I2R drop of potential method should be used.
Companies engaged in the former, credit a large percentage of their losses to leaky valves and defective mains. The remedy may involve heavy expense and the loss is often tolerated as the lesser of two evils.
In electric power distribution the transformer takes in part the place of the valve and pipe system. An inferior or defective transformer usually treats both the central station and its customers badly, being in this respect more impartial than the gas or water pipe which may annoy but one of the interested parties at a time.
Like a neglected or defective gas fixture a transformer can menace life, failing, however, to give the warning the former gives, and with a more hidden threat on account of its location.
Fig. 2,014.—Diagram of connections for regulation test. Connect transformer under test to high tension supply circuit. A second transformer with same or other known change ratio is also to be connected up, as illustrated. By means of a double pole double throw switch, the voltmeter can be made to read the pressure on the secondary of either transformer. Supposing the same change ratio it is evident that if both remain unloaded the voltmeter will indicate the same pressure. A gradually increasing lamp load up to the limit of the transformer capacity, will be attended by a drop in pressure at the terminals. This drop can be read as the difference of the voltmeter indications, and when expressed in per cent. of secondary voltage stands for "regulation." Remarks: The auxiliary transformer is necessary in order to make sure of the high tension line voltage. A large transformer under test may cause primary drop in taking power. This must be set down against it in testing regulation. The second transformer gives notice of such drop, whatever be the cause. Figs. 2,012 to 2,014 used by courtesy of the Moloney Electric Co.
Apart from this, corresponding to an exasperated customer who complains at home and to his friends of dim lamps, blackened lamps, you will find in the power station the manager, who, also worried and in no better humor, contemplates the difference in meter readings at the end of the line.
His business does not increase and would not increase even if he could lower the rates, which he cannot do because of these meter readings.
He may be confident of his engines and generators, and that his line is up and all right, but he very seldom knows what the transformers are doing on top of the poles. Perhaps he feels that this waste is so slight that it makes no material difference. This can be readily ascertained by means of a set of testing instruments.