Electrical news and engineering . for operating the rheostat motors in one direction or the other.(3) A special generator field rheostat operating at a high rate of speed. The control element consists essentially of a set of con- tacts jointly actuated by an alternating current and a directcurrent coil. These contacts control the direction of rotationof the rheostat motor through two reversing contactorswitches. The coil is connected to the generator leadthrough the use of a suitable potential transformer. coil is connected across the terminals of the generatorfield. ? The regulat
Electrical news and engineering . for operating the rheostat motors in one direction or the other.(3) A special generator field rheostat operating at a high rate of speed. The control element consists essentially of a set of con- tacts jointly actuated by an alternating current and a directcurrent coil. These contacts control the direction of rotationof the rheostat motor through two reversing contactorswitches. The coil is connected to the generator leadthrough the use of a suitable potential transformer. coil is connected across the terminals of the generatorfield. ? The regulator is either put in or out of service bymeans of a single drum control switch. When it is desiredto place in service or remove the regulator from service,the turning of this one switch places the machine either onhand control or under the control of the regulator. Fig. 1 shows a simplified diagram of this regulator. The regulator operator as follows: Assume that a slightover-voltage exists on the generator due to a sudden drop. Fig. 2 of a portion of the load. This will cause the control leversto become out of balance, and close the upper contacts. Thisclosure energizes the upper coil and de-energizes the lowercoil of the reversing switch marked LS causing contactS to open, and contacts L and b to close. ContactL closes the circuit through the motor armature which inturn, starts cutting in resistance of the generator rheostatinto the field circuit. At the same moment, contact bshunts a small amount of current from the alternating cur-rent coil on the control element, and in effect, recalibratesit for a slightly higher voltage. This causes the core to dropopening the main contact which in turn de-energizes thecoil in the upper and lower portion of the reversing switchLS and this switch consequently opens its main contactL and auxiliary contact b and closes the lower main con-tact S. Since contact T of the other reversing switchis in the closed position, the armature of the motor
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