Electric railways by Ashe Sydney Whitmore

Author:Ashe, Sydney Whitmore. [from old catalog] & Keiley, John D., [from old catalog] joint author
Language: eng
Format: epub
Tags: Electric railroads. [from old catalog]
Publisher: New York, D. Van Nostrand company
Published: 1905-03-25T05:00:00+00:00

spring, so that the power is cut off whenever the motor-man releases the handle.

There are five circuits leading from the master con-

troller, and five corresponding train wires for the control proper. There is also a sixth circuit in the train line, which is used for an emergency cut-off, which will be described later. The five circuits comprise one for forward direction, one for reverse, one each for series and parallel, and the fifth for controlling the acceleration.

When the master controller is moved to its first position (say forward), the forward direction wire is energized, which throws the reverser to its forward position, and when so thrown, energizes contactors in the main or trolley leads to'the motors. At the same time the series contactor is energized and the circuit through the motors is completed in series, with all resistance in circuit giving a slow speed forward. In this position no further action is produced. When the master controller is moved to its second position, circuit is completed through the accelerating wire (No. i) in addition to the above circuits, which energizes the contactor, shunting the first resistance step, and current also passes through the fine wire coil and the contacts of the throttle relay. The plunger in this relay has a lost motion, so that an appreciable time is required to move it, and this time is made the same as that required by the contactor in closing its contact. These two devices thus operate simultaneously. The contactor being lifted, shifts its operating coil by means of the auxiliary contacts carried on its stem into the circuit through the series contactor above mentioned, which maintains it in the closed position independent of the circuit that has lifted it. At the same time the relay has opened the Hfting or actuating circuit. The shunting of the resistance step by the contactor causes an increased current to flow through the motor circuit and through the heavy coil of the relay,

TYPES OF CONTROL AND THEIR OPERATION. 155

which is sufficient to hold the relay plunger in its raised position, and so keep the actuating circuit open until the motors, by speeding up, cause the current to diminish enough to allow the relay plunger to drop and again close the actuating wire. Circuit is now established through the contactors shunting the second resistance step (the first contactor having shifted this circuit also), and these contactors are energized and the relay again lifted and held up by the increased current, and so on until all the resistance is cut out. I

When the master controller is moved to the third jxraition, the parallel circuit is established, followed by the closing of the bridge — contactor and the parallel contactors. The motors are then in multiple arrangement. When the master controller is moved to. its fourth or full-on position, the resistance is cut out step by step, as in series. These same successive actions are produced if the master controller is thrown to the full-on position directly,as the interlocking contacts prevent an advance circuit being established before the proper

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