US1475185A - Automatic motor starter - Google Patents

Description

Nov. 27, 1923. I 1,475,185

B. W. JONES AUTOMATI C MOTOR STARTER Filed March 1'7 1921 Fig. I.

L \C a L Inventor": Bemarhih W. Jones,

whim

His Attorneg 1 matically connected to the source of supply Patented Nov. 27, 1923.

UNITED STATES BENJAMIN JONES,

v 1,475,185 PATENT orr cs.

OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

. AUTOMATIC MOTOR STARTER.

Application filed March 17, 1921-. Serial No. 452,988.

T 0 all whom it may concern:

Be it known that I, BENJAMIN W. JoNEs, a citizen of the United States, residing at Schenectady, count of Schenectady, State of New York, have mvented certain new and useful Improvements in Automatic Motor Starters, of which the following is a specification.

My invention relates to an improved arrangement for starting electric motors, and is particularly adapted for use with alternating current motors of the squirrel cage rotor type which are started by first applying a reduced potential and then applying a higher potential, .but my invention is not limited to this particular type of motor. A

common arrangement for starting alternating current motors includes a starting compensator with low voltage taps to which the motor is first connected before being autofor normal running. My invention has a particular utility in such starting arrangements, but is not necessarily limited thereto.

One of the objects of my invention is to pr vide an improved time limit control arrangement whereby a time interval will be introduced between the closing of the successive accelerating switches.

My invention has features of simplicity of construction and arrangement, and rel1- ability and efi'ectiveness, which will be pointed out particularly hereinafter.

For a better understanding of the invention, reference is had to the accompanying drawing which illustrates one embodiment of the invention for purposes of illustration, and in which Fig. 1 is a simplified motor control system, and Fig. 2 is a simplified exploded illustration of the time element relay shown diagrammatically in Fig. 1.

Referring to the drawing, it will be ob-" served by those skilled in the art that I have illustrated my invention in very diagrammatic form in an automatic time limit starting arrangement for a three-phase squirrel cage rotor type induction motor 10 which is adapted to be connected to the low voltage taps of the starting compensator 11 or di rectly to the supply circuit 13 for normal running. The electromagnetic switch 14 is provided for connecting the starting compensator to the supply circuit 13 and the motor to the reduced voltage taps of the starting compensator, and the electromagshaft 24.

netic switch 15 is provided for connecting the motor directly tothe three-phase source of supply. For the sake of convenience, I shall term the electromagnetic switch 14 the starting switch and the electromagnetic switch 15 the running switch. The startmg and running switches are controlled by means of a time limit relay 16, the elements of which are shown in Fig. 2. Referring to Fig. 2, the time limit relay comprises a resihent switch member 17 which is connected to the pivoted armature 18 of an electromagnet 19 having a winding 20'. The. righthand end of the switch member 17 is adapted to makeengagement with a static-nary contact 21, and the left-hand end of the switch member 17 is biased to normally make engagement with the contact 22 in the lower positlon and is adapted to make engagement with the contact 23 in the upper position of the switch member. The armature 18 of the electromagnet 19 is secured toa shaft. 24 which provides a pivotal support for the armature, and the arrangement is such that the movement of the armature 18 from and to its attracted position rotates the Secured to the shaft 24 is an arm 25 which carries at one end the gear Wheel 26, rotatably mounted on a shaft 27, secured to the arm 25. The gear wheel 26 is adapted to rotate against the tension of a spring 28 mounted on the shaft 27. The time limit relay is also provided with a mo 'tor element which comprises the laminated form an induction disc alternating current motor. The disc 31 is secured to a shaft 32 which is provided with a worm 33 for the purpose of driving the gear 34 which is secured to the shaft 35. On the opposite end of the shaft 35, there is mounted a pinion 36 which is provided for driving the gear 26. The arrangement is such that when the winding 20 of the electromagnet 19 is energized, the armature 18 will be attracted and the gear wheel 26 will be rotated clockwise into mesh with the pinion 36. The gear wheel 26 will be rotated counter-clockwise so as to cause the pin 37 to make engagement with the arm 38 of the bell crank lever, the other armof which is provided with a kicked-up end 39 which holds the switch member 17 into engagement with the contact 22 until the pin 37 turns the bell crank ment with the contact 23.

The particular construction of the time element relay shown and described is the invention of Chester I. Hall. on which he filed an a plication for patent, Serial N'o.502,914, on e-ptember 24, 1921, and which he assigned to the same assignee to whom this invention is assigned.

As thus constructed and arranged, and with the parts in the various positions shown in the drawing, the operation of my invention is as follows: In order to start the motor, the normally open start push button or master switch 42 will be depressed, thereby energizing the winding of the starting switch 14 through a circuit including the contacts of the overload relays 43 and 44, the stop push button 45, the start push button 42, switch member 17 of the time limit relay 16, contact 22 of therelay, winding of the starting switch, to another conductor of the threephase supply. The starting switch 14 will be closed, and in closing will open the auxiliary switch 46 included in the circuit of .the winding of the running switch. The

motor will thereby be connected to the source of supply through the starting compensator 11 at a reduced voltage. The windings 20 and 30 of the time limit relay will be energized upon the closing of the start push button 42, and the armature 18 of the relay will be rotated clockwise so as to cause the righthand end of the switch member 17 to make engagement with the contactor 21,.thereby short circuiting the start push button 42 and permitting the start push button to be released. (It will be understood that the push buttons 42 and 45 constitute master switch mechanism for controlling the motor). The left-hand end of the switch member 17 will be put under strain tending to bias it to make engagement with the contact 23 but will be held in engagement with the contact 22 by means of the kicked-up end 39 of the bell crank of the relay. \Vhen the armature 18 is attracted into engagement with the magnetic structure of its operating electro-magnet, gear 26 will be rotated into engagement with the pinion 36 and will be driven by the disc armature 31 of the motor element of the rela The disc 26 will be rotated countercloc wise until the pin 37 makes engagement with the arm 38 of the bell crank, and finally it moves the kicked-up end 39 out of enreason of the strain put on the switch member. WVhen the switch member 17 breaks engagement with the stationary contact 22, the winding of the starting switch 14 will be deenergized and this switch will open,

closing the auxiliary switch 46, so that when the switch member 17 of the relay makes engagement with the contactor 23, the circuit for the winding of the running contactor will be completed through a circuit including the contacts of the overload relays 43 and 44, stop push button 45, contact 21, switch member 17, contact 23, winding of the running contactor 15, auxiliary switch 46, to another conductor of the three-phase supply. The running switch will now be energized to close and connect the motor directly to the supply circuit. The windings 20 and 30 of the time limit relay will remain energized, but the arm 38 of the bell crank lever will make engagement with a stop 48 and the disc 31 of the relay will stop rotating.

In order to stop the motor, the push button 45 will be depressed, thereby deenergizing the running switch and the windings of the time element relay. The running switch will open and the switch member 17 will be permitted to quickly make engagement with the contact 22 and break the engagement with the contact 21. The arrangement is thus restored to its original condition quickly preparatory to again starting since the deenergization of magnet 20 also throws the gear 26 out of mesh with the pinion 36 and the gear 26 will thereby be quickly returned to its original position by the spring 28. V

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is

1. A system for controlling ,electric motors comprising two electromagnetic switches, a resilient switch member normally held-in one position, means for putting the switch member under strain to bias the same toward a second position and for releasing the switch member after a definite interval of time to move quickly in accordance with its bias to the second position, and connections whereby the winding of the first electromagnetic switch is energized in the first position of the switch member and the winding of the second electromagnetic switch is energized in the second position of the switch member.

2. A system for controlling electric motors comprising two electromagnetic switches, a switch member normally biased to one position, means for holding the switch member in the said position, means for biasing the switch member toward a second position and for releasing the holding means after a definite interval of time to permit the switch member to move quickly to and be held in its second position in accordance with its bias, and connections whereby the winding of the first electromagnetic switch is energized in the first position of the switch member and the winding of the second electromagnetic switch is energized in the second position of the switch member.

' 3. A system for controlling electric motors comprising two electromagnetic switches, a master switch for controlling the same, a. switch member normally biased to one position, means for holding the switch I member in the said position, an electromagnot controlled by the master switch for biasing the switch member toward a second position, means controlled by the master switch for releasin the holding means after a definite interva of time to permit the switch member to move quickly to the second position'and then held in that position by the said electromagnet, and connections whereby the winding of-the first electromagnetic switch is energized in the first position of the switch member and the winding of the second electromagnetic switch is energized in the second position of the switch member.

4. A system for controlling electric motors comprising two electromagnetic switches, a switch member normally biased to one position, means for holding the switch member in the said position, electromagnetically controlled means for biasin the switch member toward a second position, an electromag- .the first position of the switch member and the winding of the second electromagnetic switch is energized in the second position of the switch member. I

5. A system for controlling electric motors comprising two electromagnetic switches, a

switch member normally biased to one position, means for holding the switch member in the said position, electromagnetically controlled means for biasing the switch member toward a second position, an electromagnetically controlled timing mechanism for releasing the holding means after a definite interval of time to permit the switch member to be moved quickly to the second position in response to the bias set up by the said electromagnetically controlled means, and connections whereby the winding of the first electromagnetic switch is energized in the first position of the switch member and the. winding of the second electromagnetic switch is energized in the second position of the switch member, the arrangement being such that the switch member and the timing mechanism are quickly returned to their original positions in response to the deenergization of the electromagnetically controlled biasing means and the electromagnetically controlled timing mechanism.

6. A system for controlling electric motors comprising two electromagnetic switches, a time element relay for controlling thesame having a switch member normally biased to one position, a normally open master switch for controlling the relay, the said relay having means for holding the switch member in the said position, electromagnetically controlled means for blasing the switch member toward a second position. an elec-trorcsponsive timing device for releasing the switch member after a definite interval of time to move to the second osition, and connections whereby the first e ectromagnetic switch is ener ized in the first osition of the switch mem er, the second e cctromagnetic switch is energized in the second position of the switch member, and the said master switch is short circuited both when the switch memher is biased toward the second position and when the switch member is in the second position.

7. A system 'for controlling electric motors comprising two electromagnetic switches, a switch member normally held in one position, means for biasing the switch member toward a second position and for releasing the switch member after a definite interval of time to move quickly in accordancewith its bias to the second osition, means for varying at will the said time interval, and connections whereby the first electromagnetic switch is energized in the first position of the switch member, and the second electromagnetic switch is energized in the second position of the switch member.

In witness whereof, I have hereuntoiset my hand.

BENJAMIN w. JONES.

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