Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916 Excerpt: ... the rotating-M to produce a torque or field proportional to the power in the circuit and this torque is counterbalanced by the retarding element so that the speed of the disk is exactly proportional to the torque. The retarding element consists of two permanent magnets mounted on that side of the meter diametrically opposite to the field coils and between the poles of which the metal disk of the moving element rotates. The magnet poles develop an electromotive force between the inner and outer parts of the disk that sets up eddy currents in it which consume the power passing through the field magnet coils. The registering mechanism comprises the dials, pointers and the gear wheels necessary to secure the required reduction in speed to enable the dials to register directly in watthours. A power factor adjustment consisting of a shortcircuited loop of variable resistance enclosing part or all of the shunt field flux, and acting like the secondary of a transformer, enables the phase angle between the shunt and series field currents to be made exactly 90 degrees with 100 per cent, power factor in the metered circuit. This is a necessary adjustment to be made in order that the strength of the rotating field be a measure of the actual power in the circuit metered,--a condition upon which the proper operation of the instrument depends. 606. If the pointers on the dials of a watt-hour meter indicate as shown in Fig. 200, what is the correct reading? Considering, first, the position of the pointer on the scale furthest to the right, it is seen to be on 2. One complete revolution of the pointer on this scale indicates 1000 watthours, each of the ten divisions being equal to 100 watt-hours. The 2, therefore, on the right-hand scale denotes 200 watthours. Passing to t...
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