US1637054A - Controller for electric motors - Google Patents

Description

July 26, 1927. 1,637,054

E. w. SEEGER CONTROLLER FOR ELECTRIC MOTORS Filed Sept. s. 1925 INVENTOR.

WM WWW)! ATTORNEY fects restarting without the Patented July 26, 1927.

' UNITED STATES PATENT OFFICE.

EDWIN W. SEEGER, 0F MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLII]R-llI-IAIVI MER MFG. 00., 0F MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

CONTROLLER FOR ELECTRIC MOTORS.

Application filed September 5, 1925.

This invention relates to controllers for electric motors, and more particularly to motor starters of the C. E. M. F. type.

Motor starters of the aforesaid type usually include an electro-responsive main switch for controlling the power connections ofthe motor and one or more .electro-responsive switches for excluding steps of resistance in the motor circuit. The main switch is usually push button controlled, and in responding is adapted to maintain itself in closed position through the medium of auxiliary contacts associated therewith while the accelerating switches are provided with operating windings connected across the motor armature to render the same responsive to given counter voltage conditions in the armature circuit. In practice itjhas been found that upon interruption of the motor circuit by the main switch the accelerating switches usually remain in closed position until the motor is practically stopped, whereby. reclosure of the. main switch prior to stopping of the motor efprotective accelerating resistance in circuit.

The present invention has among its objects to provide a motor starter of the C. E. M. F. type having means associated therewith for insuring inclusion of the accelerating resistance immediately upon interruption of the power connections for the mo tor. Y i

Another object is to provide a motor starter of the aforesaid character including means controlled by the auxiliary maintaining contacts of'the main switch for insuring inclusion of the accelerating resistance immediately upon opening of said main switch. I

Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawing diagrammatically illustrates an embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of modification without departing from the spirit and scope of the ap pended claims.

Referring to the drawing, the same illustrates a compound wound motor M having an armature A, a series field winding F and a shunt field winding F Motor M is adapted to be connected across lines L-L a switch 2 is provided for fully described. Closure ,to" prevent closure of Serial No. 54,641.

by an electro-responsive main switch 1,. and

of accelerating resistance circuit.

The operating winding 1 of main switch 1 1S controlled through the medium of a normally open starting push button '3 and a normally closed stop push button 4, and said mam switch is also providedwith' auxllrary contacts l for establishing a maintaming circuit therefor upon release of push button 3. provided with two operating windings 2 and 2*, and, for purposes hereinafter set forth, said windings are connected to oppose each other under certain conditions and to act cumulatively under other con ditions.

The function and operation of the aforedescribed controller, together with the circult connections therefor will now be more of push button 3 establishes an energizing circuit for main switch 1 extending from line L through. push buttons 3 and 4, by conductor 5 to and through the operating winding 1 of switch Land by conductor 6 to line L Closure of push button 3 also establishes circuit from line L through said push button, by conductor. 7 through operating windings 2" and 2, by conductor 8 through the. field F, by conductor 9 through resistance R to line However, windings 2" and 2 are so arranged that when the same are connected in the aforesaidmanner theyact in opposition switch 2. Upon closure of switch 1 the motor is Y connected across lines L and L through resistance R and upon release of push button 3, switch 1 maintains itself in closed position by a circuit extending from line L, by conductor 10 to and through the auxiliary contacts 1', by conductor 9 to and through the operating winding 2 by conductor 7 through push button 4,by conductor 5 to and through the operating winding 1 and by conductor 6 to line L Also,upon closure of switch 1 and release of push button 3, the auxiliary contacts 1 connect the winding 2 across the terminals of the armature A to render the current in said winding dependent upon the G. E. M. F. of the motor armature. Windings 2* and 2 then act cumulatively, and, when the C. E. M. F. of the motor armature rises R in the motor excluding a step c Accelerating switch '2 is to a given value, windings 2 and 2" effect closure of switch 2 for exclusion of resistance R in the motor circuit.

Opening of push button a interrupts the aforedescribed maintaining circuit for switch l and'said main switch in opening immediately disconnects the winding 2 from the motor circuit to insure opening of accelerating switch 2.

The controller thus functions to prevent restarting of the motor without the accelerating resistance R in circuit therewith, and it'should be noted thatdue to connection of the windings 2 and 2 ofthe accelerating switch in the manner aforedescribed the controller functions without'the use of auxiliary control contacts other than those which are usually employed for establishing a maintaining circuit for the main switch. Further it should push button 3 is held in closed position switch 2 is rendered unresponsive, whereby opening and reclosure of push button +1 provides forinching operation of the motor at slow speed.

WhatI claim as new and desire to secure by Letters Patent is:

1. In a motor control system, the combination with an electric motor, of an-electroresponsive line switch for controlling the circuit of said motor, an electro-responsive accelerating switch for said motor, means for controlling the energizing circuit of said line switch and for'alsoestablishing a maintaining circuit therefor upon closure thereof, and a plurality of operating windings associated with said'accelcrating'switch and controlled by said means to provide for delayed closure of said accelerating switch upon closure of said main switch and for immediate opening of said accelerating switch upon opening of said main switch.

'2. In a motor control system, the combination with an electric motor, of an elect-roresponsive line switch and an accelerating switch therefor, control means for said line switch including auxiliary contacts for establishing a maintaining circuit therefor upon closure thereof, a plurality of operatbe noted that as long as ing windings associated with said accelerating switch and circuit connections between said windings and said auxiliary contacts providing for connection of one of said windings. in the motor circuit upon closure of said line switch and for connection of the other of said windings in the maintaining circuit of said line switch upon closure of the latter, said windings when so connected being adapted to act cumulatively to effect closure of said accelerating switch.

3. In a motor control system, the combination with an electric motor, of an electroresponsive line switch therefor, control means for said line switch including auxiliary contacts associated therewith for cstablishing a maintaining circuit therefor upon closure thereof and an electro-rcsponsive accelerating switch having a plurality of operating windings, one to be connected, by said contacts, across a portion of the motor circuit and the other to be connected, by said contacts, in series in the energizing circuit of said line switch, said windings when so connected being adapted to act cumulatively to effect closure of said accelerating switch under given electrical conditions in the motor circuit.

4. In a motor control system, the combination with an electric motor, an electroresponsive line switch for controlling the circuit of said motor, a normally open and a normally closed push button in the energizing circuit of said line switch, the former being adapted to establish an energizing circuit for said switch through the latter, auxiliary contacts associated with said line switch for establishing a maintaining circuit therefor through the medium of said normally closed push button, and an accelerating switch having a plurality of operating windings, one to be connected in shunt with the motor armature by said auxiliary contacts and the other to be connected in series in the maintaining circuit of said line switch by said auxiliary contacts.

In witness whereof, I have hereunto subscribed my name.

EDWIN W. SEEGER.

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