The cores
are then bolted to the yokes vertically from the top and horizontally
below. The field of this machine is shunt-wound, and in order to
maintain the potential constant a hand-regulated resistance--R2 on
the switch board--is added in circuit with the shunt field. The
voltmeter, V2, immediately above this resistance, serves to
indicate the difference of potential at the machine terminals. Both
voltmeters are fitted with keys, so that they are only put in circuit
when the readings are taken.
The main terminals of this machine are fitted on substantial
insulating bases, fixed one at each end of the top yoke. These connect
to the external circuit by a heavy cable--the machine being capable of
developing 500 amperes--and to the shunt circuit, and regulating
resistance by small wires; while the two connections to the brushes
are by four covered wires in parallel on each side. This mode of
connection is more flexible than a short length of heavy cable, and
looks well, the wires being held neatly together by vulcanized fiber
bridges. The dynamo is a low tension machine, the field being
regulated to give 65 volts when running the lamp circuits.
[Illustration: Fig. 10.]
The illustration, Fig. 10, represents the automatic
re-regulator--C.E.L. Brown's patent. Motion is imparted to the cores
of two electro-magnets at the ends by the pulleys, W W1.
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