. Journal of electricity, power, and gas . A very convenient and flexible laboratory test-ing board is shown diagranimatically in Fig. 96, whichcan be used for testing single phase watthour metersof voltages from 100 to 500 inclusive, and of any am-pere capacity, the load being regulated by switchingmore or less of the lamps in circuit by means of thesingle pole switches, L. The indicating wattmetermay be of 5 or 10 ampere capacity, and can be conveni-ently mounted in a horizontal position on a swingingbracket; the current transformer being of a 5 or 10to I ratio, or if desired, several curren
. Journal of electricity, power, and gas . A very convenient and flexible laboratory test-ing board is shown diagranimatically in Fig. 96, whichcan be used for testing single phase watthour metersof voltages from 100 to 500 inclusive, and of any am-pere capacity, the load being regulated by switchingmore or less of the lamps in circuit by means of thesingle pole switches, L. The indicating wattmetermay be of 5 or 10 ampere capacity, and can be conveni-ently mounted in a horizontal position on a swingingbracket; the current transformer being of a 5 or 10to I ratio, or if desired, several current transformers ofdifferent ratios may be used. For testing iio-volt watt-hour meters of capacities not greater than the capacityof the indicating wattmeter, the switch S isthrown in the downward position, thus putting poten-tial on the lOO-volt tap of the indicating wattmeter andon the potential winding of the watt hour meterthrough the variable resistance; at the same time switch S is thrown down, thus connecting the. Thorrs ^f^nri indicating wattmeter directly into the circuit. Bythrowing S up, the current transformer is connectedinto circuit when it is desired to test higher capacitymeters. The correct load, as near as possible, is ob-tained by closing the switches L, and a finer adjust-ment is accomplished by means of the variable resist-ance shown in the diagram. This variable resistanceis most conveniently made up by wrapping a bareresistance wire on a suitable mandrel and having asliding contact which will not interrupt the circuit inpassing from one turn of the wire to the next. Bymeans of this variable resistance, the tester can holdthe load on the wattmeter constant while the test isbeing made. For testing 200-volt meters, the switch S isthrown in the upward position, and S is thrown downor up according to whether the meter in test is belowor above the capacity of the indicating wattmeter. For testing 500-volt meters the switch S is closed,vvrhich
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Keywords: ., bookcentury1800, bookdecade1890, bookidjo, booksubjectelectricity
