US1387466A - System of control - Google Patents

Description

A. H. CANDEE.

SYSTEM OF CONTROL.

APPLICATION FILED ocr. 30. ms.

INVENTOR Andrew H Cafldze A.TTORNEY WITNESSES: H} X KM UNITED STATES PATENT OFFICE.

ANDREW H. CANDEE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, CORPORATION OF PENN- SYLVANIA.

SYSTEM OF CONTROL.

To all whom it may concern:

Be it known that I, ANDREW H. CANDEE, a citizen of the United States and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a specification.

- My invention relates to control systems and particularly 'to the control of storagebattery locomotives and the like.

One object of my invention is to provide a system that is adapted to fulfil all the functions of previous systems of the aboveindicated character without requiring the use of as many switches, whereby reductions in first cost and maintenance and in space and Weight requirements are efi'ected. Another object of my invention is to so connect a resistor in'circuit, in systems of the type under consideration, that not only may a certain number of switches be eliminated, but the resistor may also be employed forshunting the motor field winding to assist in providing an additional accelerating step.

In the construction of control systems for mining'locomotives' and the like, it is imperative to reduce the space requirements to a minimum, by reason of the narrow passages through which the locomotive must run. The present invention fulfils this requirement in a. material degree and, moreover, also, eifects a decrease in the cost of the system, sinceaa' certain number of circuit switches or equivalent drum-controller contact members are eliminated with respect to previous systems of this general class.

My invention may best be understood by reference to the accompanying :drawing, wherein Figure 1 is a diagrammatic view of the main circuits of a" system ofcontrol embodying my invention; Fig.2 is a sequence chart of well-known form, indicating the preferred order of. operation of theIvarious switches that are illustratedinFig. 1; and Fig. 3 to Fig. 13, inclusive, are simplified diagramatic views illustrating the circuit connections that. are obtained during various operating periods of the control system. 1

Inasmuch as it is within the province of any engineer skilled in the control art to readily devise a master. controller, or the Specification of Letters Patent. .Patent d A 16 1 2 Application filed October so, 1918. Serial No. 260,281.

equivalent, for manually governing the various switches in the sequence indicated in Fig. 2, I have not deemed it necessary to illustrate and describe any such master controller, but it is believed that the sequence chart, together with the numerous simplified;d1agrams, will serve to fully disclose my invention.

Referring to Fig. 1 of the drawing, the system shown comprisesa suitable source of energy, such asa storage battery B that is carriedupon the locomotive; a plurality of propelling motors, one of which has a commutator-type armature 3 and an exciting field winding having two sets of distinct portlons or sections 4 and 5, and the other or whlch has similar armature and field windings 6, 7 and 8, respectively; a plurality of resistors 9 and 10, each of which is used for the double purpose of varying the armature-circuit resistance and shunting the field'vvindings; a plurality of unit switches, or'the equivalent, F1, FF 1, F2, FF2, R1, RRl, R2 and BB2, the first four of which are employed to efi'ect forwardoperation of the locomotive, while the last four are utilized to produce reverse running; and a plurality of circuit-adjusting switches S, B, R

RR, 1, 11, 2, 22, P1, P2 and P3. Although, for the sake of simplicity and clearness, only two field-winding sections are shown associatechwith each motor, it should be understood that the actual preferred construction embodies four polar projections severally provided with two separate portions that respectively constitute a part'of the illustrated windings 4 and 5, for example. a 1 Assuming that it is desired to effect for ward operation of the locomotive, the master controller (not shown), or its equivalent, is actuated to its first step or position a, whereby switches S, B,F1, FFl, F2 and FF2 are closed, as indicated by the first line of the sequence chart, Fig. 2.

A circuit is thereby established from the positive terminal of the battery B through conductors 13 and 14:, switches S and F1, armature 3, switch FFl, conductor 15, fieldwinding section 4, resistor 9, conductor 16, field-winding section 5, conductor 17, switch F2, armature 6, switch FF2, field-winding section 8, conductor 18, resistor 10, fieldwinding section 7, switch B- and conduc-.

tor 19 to the negative battery terminal. The straight series connection of all armature and field windings with the resistors 9 and 10 that is illustrated in Fig. 3 is thus effected to start the motors into operation.

In position b of the above-mentioned master controller, switch R is closed to shortcircuit the resistor 9, as shown in Fig. 4, while, in step c. the switch RE is also closed, as illustrated in Fig. 5. to shortcircuit the other resistor 10. In this way, a predetermined degree of acceleration is imparted to the propelling motors.

As the controller is moved through transition positions (Z and e, switches 1 and 2 are closed. and the switches R and RR are then opened to short-circuit the resistors 9 and 10 together with the series-connected fieldwinding sections d and 8 of the respective motors, as illustrated in Fig. 6.

In step f. switches 11 and 22 are closed to connect the pairs of field-winding sections 4 and 7, and 5 and 8, respectively, in parallel relation to the same resistors 9 and 10, as shown in Fig. 7. The field-shunting connections described above serve to effect further acceleration of the propelling motors in accordance with well-known principles. It should be noted, however, that the use of the same resistor for shunting both field-winding sections of one motor, which resistor is that initially used for excluding resistance from the main circuit, effects a certain economy in cost and weight of the control apparatus. In particular, one switch is dispensed with by shunting the resistor across the field-winding sect-ions rather than opencircuiting the resistor. Since, in all practical railway series-motor cases, the resistor would have a relatively high resistance compared with that of the field-winding sections, it follows that the increase in speed that is secured by step 7 is almost the same as that obtained by a plain changeover of the field winding sections from series to parallel relation.

The system is now in readiness for transition to the parallel relation of the motors. In transition positions 9, h and 2', the controller first releases the switches 2 and 22 to produce the straight series connection of the armature 6 and its field-winding sections with the resistor 10, as illustrated in F 8, next closes the switches P1 and P2, thus providing a direct connection between conductors 13 and 17 to shunt the entire motor having the armature 3, as shown in Fig. 9, and finally opens switches S, 1 and 11, while closing switch R, to temporarily disconnect the shunted motor from circuit and, at the same time, short-circuit the resistor 9, as illustrated in Fig. 10. It will be appreciated that, if desired, a single switch of sufiicient currentcarrying capacity may be substituted for the two light-weight switches P1 and P2, which are here used for special engineering reasons: namely, to afford interchangeability of all the illustrated switches, with the consequent advantages.

In the next running position j, switches "0 BR and P3 are closed, thus connecting the temporarily short-circuited terminal of the armature 3 to the negative battery terminal and concurrently short-circuiting the resistor 10, as shown in Fig. 11. The motors are 7 thus connected in full-parallel relation across the battery terminals, with full field-winding excitation.

In transition positions and Z, switches 1 and 2 are first closed again and then switches It and RR are opened to shunt the resistors 9 and 10 together with the fieldwinding sections 4- and S, as illustrated in Fig. 12.

In the final running position m, switches 11 and 22 are closed to again shunt the pairs of field-winding sections across the resistors 9 and 11, respectively, thus producing the weak-field connections, with the motors connectod in parallel relation, as shown in Fig. 13.

It will be seen that I have thus provided a system wherein a number of resistor-shorteircuiting switches are eliminated by reason of the permanent connection of resistors between the field-winding sections of each motor, and the cost and space and weight requirements of the system are still further reduced by utilizing such accelerating resistors to subsequently shunt the field-winding sections. The ohmi: value of each resistor, in all practical cases, will be relatively high compared to the resistance of the field windings, being at least thirty times the resistance of the field windings 5 when connected in parallel relation. Consequently, the losses in the resistors, when used for the field-shunting purpose, will be relatively small.

I do not wish to be restricted to the speciliccircuit connections or arrangements of parts herein set forth, as various modifications thereof may be made without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. The method of accelerating an electric motor having an armature and a plurality of field-winding sections in conjunction with a resistor permanently connected intermediate said sections that consists in shortcircuiting said resistor, short-circuiting one field-winding section together with said re- 12 sistor, and shunting the resistor across both field-winding sections.

2. In a system of control, the combination with a dynamo-electric machine having an armature and a twosection field winding,

of a resistor permanently connected intermediate said sections, and three switches respectively connected across the resistor alone and across the resistor together With the one or the other field-Winding section.

3. In a system of control, the combination with a dynamo-electric machine having an armature and a plurality of field-winding sections, of a resistor permanently connected 10 intermediate said sections, means for exeluding said resistor from circuit, means for short-circuiting one field-Winding section together With said resistor, and means for shunting the resistor across both field-winding sections.

In testimony whereof, I have hereunto subscribed my name this 26th day of Oct., 1918.

ANDREW H. GANDEE.

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