[Electric engineering.] . 3,600 Meter watts = 300. 60 f$f = .99, or 99$. Ans. The meter is, therefore, 1 per cent, too slow, and the dampingmagnets should be shifted in a little so that the retarding action on thedisks will not be so great. 115. If a standard wattmeter is not available for test-ing purposes, separate ammeters and voltmeters may beused for direct-current work, but they are not as convenient. 98 ELECTRIC TRANSMISSION. § 14 In Figs. 47 and 48, it will be noticed that the energy con-sumed in the potential circuit of either meter is not meas-ured by the other; that is, the current
[Electric engineering.] . 3,600 Meter watts = 300. 60 f$f = .99, or 99$. Ans. The meter is, therefore, 1 per cent, too slow, and the dampingmagnets should be shifted in a little so that the retarding action on thedisks will not be so great. 115. If a standard wattmeter is not available for test-ing purposes, separate ammeters and voltmeters may beused for direct-current work, but they are not as convenient. 98 ELECTRIC TRANSMISSION. § 14 In Figs. 47 and 48, it will be noticed that the energy con-sumed in the potential circuit of either meter is not meas-ured by the other; that is, the current in the armature ofthe Thomson meter does not pass through the fields of thestandard meter; neither does the current in the shunt of thestandard pass through the field coils of the Thomson meter. 116. To test a meter used on a three-wire 110- to 220-volt circuit it may be connected as shown in Fig. 49. Thepotential circuits of these meters are wound for 110 field coils can, therefore, be connected in series, and. Line Load Fig. 49. the standard meter connected in as shown in Fig. 49. Informula 20, however, K should only be taken as one-halfthe constant marked on the dial. Aside from this, themeter can be tested in the same manner as a two-wiremeter. 117. Cleaning Meters.—The first thing to be done incleaning meters is to blow out the dust. A small syringe isuseful for this purpose. Parts that can be reached shouldbe wiped out with a cotton cloth. Clean the top bearingand worm-gear, but do not oil them, as the oil is liable tofind its way on to the commutator. If the train of thecounter is stiff, give it a bath in gasoline. Next see thatthe brushes present a clean, flat, smooth surface to the § 14 ELECTRIC TRANSMISSION. 99 commutator. A piece of crocus cloth glued to a narrow, thinstick answers for polishing the brushes, except in cases wheregrooves are worn in them. If this is the case, a small fine-grained file maybe used before polishing. After the brushesare put
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