. Electric railway journal . on to the speed of the locomotive. For control ofvoltage magnitude an induction regulator, automatic-ally operated, is employed. Some Important Phase Relations The phase control is roughly as follows: The electro-motive force induced in the motors by rotation is inphase with the exciting flux, and this is itself in phasewith the current in the inductors, displaced about 90deg. from the voltage at the terminals of the exciting voltage in the inductors of the motorsis therefore displaced by 90 deg. from the line voltageby the aid of an auxiliary winding pl
. Electric railway journal . on to the speed of the locomotive. For control ofvoltage magnitude an induction regulator, automatic-ally operated, is employed. Some Important Phase Relations The phase control is roughly as follows: The electro-motive force induced in the motors by rotation is inphase with the exciting flux, and this is itself in phasewith the current in the inductors, displaced about 90deg. from the voltage at the terminals of the exciting voltage in the inductors of the motorsis therefore displaced by 90 deg. from the line voltageby the aid of an auxiliary winding placed on the statorwinding of the compressor motor at 90 deg. space dis-placement from the power or torque-producing wind-ing fed by the system. There is thus impressed on theterminals of the motor inductors a voltage nearly inphase with that of the low-tension side of the transfor-mers. When the motors are supplying current as generators,the reactance of their winding throws their voltage out TABLE III—LOCOMOTIVE TEST DATA. SOULOM POWER PLANT OF THE MIDI RAILWAY, SOUTH-WESTERN FRANCE of phase with that of the line. The reactance of themotor circuit, of course, includes that of the trans-formers also. This reactance is about three times asgreat as the resistance, so that as generators the motorsoperate with a powerful de-phasing effect, considerablyreducing the torque. To reduce the phase displacement between currentand flux, the motors are excited with a voltage displacedmore than 90 deg. from that of the line. This result isobtained automatically by the use of a compoundingtransformer which displaces the phase of the primaryvoltage of the transformer. Some Test Results Secured Some tests were made to determine the resistance ofthe Jeumont locomotive by determining the loss inspeed while traversing a course of given length underits own momentum. Results are shown in Table II,which gives the resistance in pounds per ton. Ob-viously the resistance thus obtained includes all com
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