US1098780A - Motor-starting device. - Google Patents

Description

P CALDWELL MOTOR STARTING DEVICE.

I APPLICATION FILED APR.5, 1913. v 1,Q98,78Q Patented June 2, 1914.

JNYEN UH CHLDJ/YELL TNESSES 4 MEAT runway:

rmr; r111) stra ns PlTEITT OFFICE.

PAUL CALDWELL, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

MOTORSTARTING DEVICE.

T 0 all to]: 0m it may; concern Be it known that I, PAUL CALDWELL, a

citizen of the United States, residing at Pittsburgh, county of Allegheny, State of vision of means whereby an electric motormay be started and stopped in a simpleand reliable manner under conditions which redues to a minimum all possibility of damage from abnormal circuit conditions and improper handling.

In the control of electric motors, especially induction motors, it is desirable that the oporation performed by the o erator of starting and stopping the motor e simplified and rendered proof against improper handling as far as ossible. usually per ormed by employees having practically no knowledge of electrical apparatus. It is desirable thatithe operation be limited to the throwing-of the switch and that the arrangement be such that the operation can not be improperly performed so as to injure the apparatus by dangerous arcing. Such motor starting apparatus is ordinarily 'provided with overload protection whereby the motor circuit will befautomatically opened upon the occurrence of an overload on the an ore rload. motor circuit after it has heen opened by circuit. Upon the occurrence of such an overload it is desirable that the motor circuit cannot'be'again started until the operator performs some operation with the control apparatus, such, for instance, the throwing of the switch. This insures that the apparatus will not be restarted without the knowledge of the operator.

In carrying out my invention I provide means whereby the starting operation may be performed by the throwing of a manually operated line switch, the arrangement being such that the motor circuit will always be opened by an elective-magnetic circuit breakerv whether it is opened intentionally or In order to again close the an overload it is'necessary for the operator to open and closethe line switch. It is'frequently desirable that in addition to thg Specification 01 Letters Patent. Application filed April 5, 7.91:). Serial No. 759,120.

These operations are- Patented June 2, 1914:.

manually operated line switch one or more control switches located at a remote point from the line switch be provided. 'When such a control switch is .used in my starting ap aratus, the motor circuit will be opened an closed at'the circuit breaker by the operation of the control'switchassuming that the line switch: is closed. Upon the occurrence of an overload, however, the circuit breaker will open and cannot be closed by the operation of the control switch but can only be closed by firstopening and closing the line switch and then operating the control switches.

In one embodiment of my invention I place the line switch and other control ap-- paratus in a casing preferably of metal and have nothing projecting from the casing but the handle of the line switch. This casingis preferably completely closed: so that the op erator will not ordinarily have access thereto. In case the control. switch is employed it is located externally of the casing and preferably remote therefrom so that in case the motor should be'stopped by the occurs rence of an overload the operator must go back to the starting apparatus and operate the line switch by the handle projecting through the casing and then return and oper'ate the control switch to start the motor.

Other objects and purposes of nay-invention will appear in the course of the following specification, in which I have shown my invention embodied in concrete form for purposes of illustration.

In the drawing, Figure 1 is a-diagram of the circuit connections and Fig. 2 repre sents the parts inclosed in a casing or box.

Referring first to Fig. 1, A represents the armature, F the series field and F the shunt field of the motor to be controlled. I have shown a. compound wound motor for pur poses of illustration, but it is obvious that my invention is in no sense limited to this particular type of motor. S represents a main or line switch for connecting the motor to the line. This switch has in addition to the main contactslO and '11, the auxiliary contacts 12 and 13 for purposes hereinafter described. The arrangement is such that as the switch closes contact 13 is first engaged and then the contact 11. 'When thev switch .fully closed the contacts 10; 11 and 12 are in engagement with the switch arms, but contact 13 is out of engagement. The par ticu lar construction of this switch forms no part of my invention, trated in a conventional manner. One of the switch arms 14 is longer than the other so as to engage the contact 13 during the closing of the switch and to engage the contact 12 after the switch is closed. An electromagnetic s itch or conductor B having a winding 15 and a switch arm 16 is provided for opening and closing the motor circuit after the line switch is closed. Associated with this contactor is an overload relay for interrupting the circuit of the contactor upon the occurrence of overload conditions. This relay forms no part of my in ention, but is described and claimed in an application of Edwin J. Murphy, Serial No. 67 1,979, assigned to the same assignee as this application. Briefly described, this relay consists of two pivoted switch arms 17 and 18. The switch arm 17 is moved to closed position upon the energization of winding 19 and when in its closed position the winding 15 of the contactor is energized. The switch arm 18 controls the circuit of the actuating winding 19 and is moved to closed position in which the winding 19 is energized by the core of the overload coil 20. The two switch arms 17 and 18 are mechanically interlocked so that each holds the other in closed position. The interlock consists of a tail piece 21 on the switch arm 18 having two notches 22 and 23 for engaging the lug 24 on the end of the switch arm 17. \Vhen the switch arm 17 is in closed position, it is held closed by the engagement of the lug 24 in the notch 22. Upon the oc currence of an overload the coil 20 will lift its core, release the switch arm 17, which will be moved to open position by the weight of the core, and movethe switch arm 18 to closed position. In this position of the switch arm 18 the coil 19 may be energized to again close or reset the switch arm 17 to energize the coil 15 of the contactor B. A control switch 25' having one terminal connected with the contact 12 and the other with the winding 15, is provided for opening and closing the circuit of the contactor through the switch arm 17 of the relay. This switch 25 is not,essential to my inyention and in case it is'np it used the contac tor B will close as soon asfhe line switch is closed and will open before the line switch is fully opened. The actuating coil 19 of the relay has one terminal connected with the contact 13, while the other terminal is connected with the switch arm 18. R and R represent two resistance sections which are successively cut out. of the motor circuit to bring it up to running speed. These resistances are cut out of circuit by means of two electromagnetic switches G and C. These but is merely illus-' two switches are of the type described. and claimed in the application of Edwin J. Murphy, Serial h 0. (308,652. The arrangement is such that when the current through .an additional windin 26 connected across the line for holding the switch closed when the current becomes very low due to a very light load on the motor. This coil is connected in circuit by a small auxiliary switch shown col'iventionally as consisting of pivoted arm 27 engaging the contact 28 when the switch C closes.

The mode of operation and the circuit mmnections of the apmratus are as follows: Assuming the parts to be in the position shown in the drawing and it is desired to start the motor, the operator first closes the line switch S. l uring the closing of this switch the long arm of the switch first engages he contact 13. In this position the actuating winding 19 of the overload relay will be energized, the circuit being vfrom the positive side of the line to the contact 13, winding 19, switch arm 18 and wire 25) to the negative side of the line. This brings the contact arm 17 to closed position and opens the circuit of the winding 1'1 at the ('Ulltill'larm 18. This happens during movement of the line switch S to closed position. When the switch is in closed position operator may then operate the control switch which may be located a remote point. on the closing of the swi 23 the contactor B will close, the circuit Lieing as follows: From the p sitivc the line to contact 12, switch wind; 7 15, wire 30, switch arm 17, wire and bee to tho'negativc side of the line, '7 1e tactor i) being closed, the motor circuit will be established from the positive side of the line through the field F, armature A, resistance R, winding 01" contactor C, res stance 1, through th'eoverload coil 20, contact arm 16, to the negative side of the line. As the' is connected in circuit vurough contacts 27 and 28, the circuit being from the positive side 01"". the line through the contact 12, control switch 25, contacts 28 and 27, winding wire 80, contact arm 17 of the overload the ' mounted relay to the negative side of the line. The cnergiZing, oi" the coil. 26 holds the switch 1'? in closed position since the actuating coil has he i1 out out of circuit. The motor now running at full speed under normal conditions. By opening and closing the ,switch 25 the motor may he started and stopped nuton'iatically at any time as desired, so long normal conditions exist. If, however, an overload should occur, control at'the switch islost since the switch arm 17 of the overload relay opens and opens the circuit of the winding 15 of the con-teeter independently of thecontrol switch. When the switch arm 17 opens, the s'wltcn arm 18 closes and is held closed by the interlocking connection between the switch. arms. In order to again startthe n'ioior itis necessary for the operator to open and close the sWitCl') S. In ening the switch the conta t 13 is engaged y the long arm l-it oi the switch and energizes the whaling 19 which closes the relay. With the switch in the closed position the con- 'tl'Ol switch may again be operated as before to close the conta tor and start the motor.

in Fig; 2 I have shown a casing or box upon a standard for containing: the control apparel as above described. This box pretend)! y made of metal and is met erably locked so as to prevent access thereto except to the proper persons. A lever 31 12,"

mounted upon a shaft extending through the cash-1g. .ly moving the lever from the pcsitionshmvn in the drawing to the position shown in dotted lines the switch will he opened, and the switch will be closed when the lever is in the position shown in the full lines, I may also and preferably do pro'i idc means for locking the switch lever in, the open position as shown in the drawing. VVit-h this arrangement no part of the control apparatus is exposed with the exception of the lever and it is only neces sary upo the occurrence of an overload for the operator to move the lever 31 down to open position shown in dotted lines and back again to restore control to the control, switch 253. This insures that the operator will, return to the motor and control apparatus after an overload has occurred to see that everything all right before restarting. it also insures that the motor will not he started without the knowledge and consent of the operator.

W rile l have described my invention cmiiodicd in concrete form and as operating in a specific manner for purposes of illustration in accordance with the provisions of the patent statutes, it should be on d riitooil that i do not limit my invention :rcto, s nce various modifications thereof will soonest,thcn'isel'vcs to those skilled in the art Without departing from the spirit oi my invention, the scope of which is set forth in the annexed claims.

What I chum as new and desire to secure 1'. The combination witltan electric motor,

of a manually operated line switch for controlling the circuit thereof, electromagnetic means for opening the motor circuit independently of said line switch upon the occurrence of overload conditions, connections whereby the motor circuit cannot be again closed after it has been opened on-an overload until the line switch is operated, and a control switch for opening and closing the motor circuit under normal circuit conditions with the line switch closed.

2. The combination with an electric motor,

of a manually operated line switch for con trolling the circuit thereof, an electromagnetic switch having its contacts in series with the contacts of the line switch for closing the motor circuit, means whereby said electromagnetic switclris opened upon the occurrence of overload conditions, connections whereby said electromagnetic switch cannot be closed after it has been openedby an overload until the line switch is operated, and a control switch arranged to control the circuit'of the electromagnetic switch under normal conditions with the line switch closed. i

3. The con'ibination with an electric motor, of a'manually' operated line switch for controlling the eircuit thereof, an electromagvnelic switch having its contacts in series with the, contacts of the line switch for clos-i mg the motor circuit, an overload relay controlling the circuit of the electromagnetic ,switch, connections whereby said relay is elcctromagnetically closed during the operation ofthe line switch, and a control switch for energizing the electromagnetic switch through 'the closed contacts of the relay to close the motor circuit.

4. The combination. with an electric motor, of a manually operated line switch for controlling the circuit thereof, an elcctron'nignctic switch having its contacts in series with the contacts of the line switch for closing the motor circuit, an clectromagnctically closed overload relay controlling the circuit of the electromagnetic switch, a contact on the line switch for closing the actuating circuit of the overload relay during, the operation of the manual switch, and a control switch for energizing the electromagnetic switch through the closed contacts of the. rclay to close the motor circuit.

5. The combination with an electric motor, of a'manually operated line switch for controlling the circuit thereof, an electromagnetic switch having, its contacts in series with the contacts of the line switch for closing ,the motor circuit, an. clcctromagrnetirally closed overload relay controlling the Ian trol switch for the electromagnetic switch,

In Witness-whereof, I have hereunto set circuit of the electromagnetic switch, a conmy hand this twenty-ninth day of March,

and auxiliary contacts on the line switch for 1913. closing the actuating circuit of the relay PAUL CALDWELL. during the operation of the switch andcon- Witnesses: necting the control switch to line when the EMMA F. LEA,

F. E. GIBLIN.

line switch is closed.

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