US759150A - Motor-starter. - Google Patents

Description

No. 759,150. PATENTED' MAY 3, 1904. W. BAXTER, JR.

MOTOR STARTER.

APPLIOATIONIILED r113. 9,-1904.

x0 nopnL; w 2 sums-sum 1.

fig 1 WITNESSES: I v /vr0 v I I I q l I w I NE TIME "dams PETERS 20.5 PHOTO-LIYMQ, wasumamm o. a.v

No. 759,150. BATENTED MAY 3, 1904.

W. BAXTBR, JR.

Y MOTOR STARTER.

APPLICATION rum) r33. 9, 1904.

N0 MODEL. I 2 sums-sum z.

16 22 0 [25 Y O I; C B

v O .X

W/T/VES-SES: //v VENTO/i Y'n: norms PETERS 00,. Fnomumq, WASNINGTONY o c.

Patented May 3, 1904.

WVILLIAM BAXTER,'JR., OF JERSEY CITY, NEW JERSEY.

MOTOR-STARTER.

SPECIFICATION forming part of Letters Patent No. 759,150, dated May 3, 1904.

Application filed February 9, 1904. Serial No. 192,823. (N model.)

To all whom zit may concern: 7

Be it known that I, WILLIAM BAXTER, Jr.,

a citizen of the United States, and a resident of Jersey City, in the county of Hudson and State of New Jersey, have invented a newand useful Improvement in Automatic Motor- Starters, of which the following is a specification.

This invention relates to automatic motorstarters, and has for its object the obviating of certain defects in such devices as now made.

The construction and operation of my invention will be fully understood from the accompanying drawings, in which Figure 1 is a diagrammatic representation of my invention in the preferred form. Figs. 2 and 3 are modifications presented for the purpose of more fully illustrating the scope of my invention. 1

Like reference-marks indicate like parts in all the drawings.

The motor is represented by A and M, the former being the armatureand the latter the shunt field-coil. At S is shown a two-pole switch to connect the motor and starter with the supply-circuit P N, Fig. 1.

The motor-starter consists of a main switch B, a rheostat-switch (J, a rheostatR R with contacts V V, and acompound-coil magnet, whose functions willbe presently explained. l/Vith theswitches B and C in the position shownin Fig. 1 the current from P, passes. to wire 1,

thence through A to wire 2,through the magnet-coil Y towire 3 and to contact V, rheostatswitch C, main switch B, wire l, andtosupplycircuitline N. From Wire 1 acurrent is shunted through wire 5-.to M, thence. to wire 6 and throughmagnet coil-X to wire 7, and thence through the rheostat R R to switch (Land thus to main-line wire N.

In automatic motor-starters as now made the .rheostat-switch C is held in the running position, asshown in the drawings, by a retaining-magnet the energizing-coil of whichis connected in series with the field M just as X is connected. in the drawings. So long as, the current flows'through this. magnet, C is retained in the running position; but if thecurrent fails G can swing counter-clockwise to the stop or open-circuit posltlon. This arrangement protects the motor frominjury if the circuit through M is broken in anyway; but at the same time it seriously damages the contacts Vof the motor-starter, for if C swings back over these contacts after the circuit through .M is broken the current passing through from C to the contacts V will be very great, and as a result the sparking between these contact-points will lac-excessive and will so roughen up the surface as to make it probable that in future backward movements of. C it will be caught-at some intermediate point and be prevented from swinging all the way to the open position. I-n addition to the retaming-magnet to hold C in the running position motor-starters as now made are provided with another magnet whose energizingcoil is connected in series with the motorarmature. open the circuit through the motor if the current becomes too strong from any cause. This magnet acts in some cases upon a separate switch and is simply a circuit -breaker. In other cases it acts to shortcircuit the magnetizing-coil of the retaining-magnet that holds C in the running position, so as to permit this switch to swing to the open position, andthus break the motor-circuit. With either construction the magnet acts effectually to protect the motor from overloads; but when it short-circuits the retaining-magnet coil it permits the rheostat-switch to swing over the contacts to the stop position when a strong current is passing from this switch to the contacts, and this, as already explained, is decidedly objectionable. To insure perfect operation of the rheostat-lever C, it is necessary that the contacts Vandthe end of C that slides over them be kept as smooth as possible, so that there may be no danger of the switch sticking at an intermediate point whenever it has to swing back to the stop position. To

. maintain these surfaces smooth, it is necessary that the operation of the starter be such that C cannot swing back to the stop position when a current is passing through it, for if a current passes at such times there will be sparking between C and the contacts V, and the edges of both parts will be burned and roughened up.

In my arrangement of motor-starter it will be seen that the magnet D E is energized by lessB is in the position shown and C rests on the coils X and Y, the former being connected in series with the shunt field-coil M of the motor and the latter being connected in series with the armature A of the motor. These two coils assist each other in energizing the magnet. If the motor is running, the switches B and (I will be in the position shown, and if the circuit through M and X is broken in any way the rheostat-switch C will not swing back over the contacts V, because the magnetizing force of coil Y will keep up the strength of the magnet and thus hold the armature F mounted uponC. If the line-current fails, both coils X and Y will become deenergized, and then the magnet will not hold armature F. Hence the rheostat-switch (I will be free to swing back to the stop position; but in this case there will be no current passing through 0, since there will be no current in the main line. The main switch B is held in the closed position by the togglejoint 12 13, one end of which is pivoted to a stationary support and the other end to arm 11 of B. The two switches B and C are mounted upon acommon stud 20 and are drawn toward each other, as indicated by the arrows a b, by the tension of spring 17, the end 18 of which engages with B, while the other end, 18, engages with C. If the motor is running with the switches B and C in the position shown and the line-current dies out, C will swing around until it strikes stop 10 on B, and thus the motor-circuit will be open, as C will not be in contact with any one of the contacts V. 1f the motor is running and the current through the armature becomes excessive, the magnetizing force of coil Y will increase until the magnet will be able to draw up 16, and then the trip-rod let will strike 13 and trip the toggle-joint, thus permitting the tension of spring 17 to draw B upward and open the motor-circuit. If while the motor is running the circuit through the field-coil M breaks, the rheostat-switch C will be held in the running position; but as soon as the motor-field weakens the armature-current will increase, and when it becomes strong enough the magnetizing force of Y will be sufficient to enable the magnet to lift 16, and thus trip the toggle-joint and permit B to swing upward and open the circuit.

From the foregoing it will be seen that when the motor is running and the motorstarter switches are in the position shown in the drawings if the main current dies out C will swing counter-clockwise until it reaches B; but if the current through the armature becomes excessive or if the field-coil circuit breaks (I will retain its position and B will swing up toward it, and thus open the motorcircuit. when the motor is stopped, the switches B and C may be in any position between that of B and that of C; but they will be both together and the motor-circuit will be open, as this circuit cannot be closed unone of the contacts V. To start the motor, the operator takes hold of the handle T on (J and moves it counter-clockwise until B reaches the position in which it is shown, and then the toggle 12 13 will become locked and will hold B until it is released by the action of the triprod 1 1. Having set B, the operator swings C clockwise gradually over contacts V to the position in which it is shown, and it will then be held in this position by the retaining-magnet. To stop the motor, the operator lifts 16, so as to trip the toggle 12 13 and permit B to swing upward.

The essential feature of my invention is the compound coil-magnet l) E, which acts to hold the rheostat-switch C in the running position under all conditions except when the mainline current dies out and which acts to open the switch B whenever the current through the armature becomes excessive from any cause.

Motor-starters are now made in which the coil Y energizes a magnet that acts to open switch B and the coil X energizes a retaining-magnet that holds switch C; but these devices fail to accomplish the result for which my arrangement is intended, because if the current through the field-coil M fails the magnetizing force of X reduces to zero, and switch 0 will swing over the contacts V while \a strong current is passing, owing to the fact that the magnetism of the retaining-magnet will die out sooner than that of the motorfield on account of the latter being so much larger. Hence C will be released before the armature-current rises to a strength suflicient to cause coil Y to act.

I have shown a toggle-joint 12 13 and trip rodl t for holding and releasing switch B; but this is simply a preferred construction and can be replaced by any of the catch and trip devices commonly used with circuitbreakers without departing in any way from my invention. I have also shown a spring on 14:, held between the stationary guide 1!) and the adjusting-nuts 15, by means of which the tension opposing the tractive force of the magnet I) E is balanced, so as to adjust the device to trip with any desired strength of current; but these details can also be varied in any desired manner. The coil X is shown connected in series with the motor-field M; but it can be located in a separate circuit that is in parallel with the motor armature, as shown in Fig. 2, without changing the operation of the starter. "ith this connection if the line-current fails coil X will be deenergized just as it would be if connected in sc ries with M. 1f the circuit through M should break, theincrease of current through Y would act, as already explained, to release B. The

placing of X in series with M is desirable, because it can be made of comparative] y large wire and a small number of turns, as the fieldcoil M balances nearly all the electromotive force of the supply-circuit. If X is connected in an independent circuit, as shown in Fig. 2, it will have to balance the whole electromotive force of the supply-circuit, and on that account will have to be made of very fine wire and many turns, and this is objectionable, not only on account of the greater cost of construction, but also on account of the greater liability of breaking the wire.

In Fig. 1 the switches 13 and G are arranged to swing around the same center; but this construction is not a necessary feature of my invention. They may be mounted on independent studs, as shown in Fig. 3, or may be made in accordance with any of the designs of motor-starters commonly used, as is illustrated clearly in Fig. 2, providing they are arranged so as to be controlled by a compound eoil-magnetin the manner herein described.

In Fig. 1 coil Y is shown connected in the motor-armature circuit; but it can be readily seen that it can be connected in wire 1 or in wire 1 above point 0, as in Fig. 2, without changing its action in any way. In fact, the only effect of this change would be to slightly increase the current flowing through the coil. I therefore claim the connecting of the coil in either of these positions.

In Fig. 2 the rheostat-switch C moves in a straight line, being guided by guide 23, and the force of gravity is utilized to return this switch, as well as the main switch and the lever 16, to the stop position. By means of a weight 22 the force acting to oppose the pull of the magnet on lever 16 can be varied.

in Fig. 3 the two switches and lever 16 are retracted by the tension of springs marked 21 21 21". The circles 24 are stops to limit the movement of the switches and of lever 16.

The coil X can be dispensed with without interfering with the action of the retainingmagnet, provided the motor is run fairly well loaded at all times; but if the load is greatly reduced the coil Y alone will not develop sufiicient magnetism to retain the rheostat switch C in the running position unless the magnet is made undesirably large. From this it will be seen that the most important oflice of coil X is to develop suflicientmagnetism to retain switch 0 in therunning position when the motor is running free or whenever the load is so light that the current passing through Y is not sufficient to enable this coil alone to develop the magnetism required to hold G in the running position. In the several drawings it will be noticed that the retaining-magnet is arranged so that the poles at one end act on one switch and the poles at the other end act on the other switch.

Having thus described my invention, what I claim as new therein, and desire to secure by Letters Patent, is the following:

1. The combination in amotor-starter, of a main switch, arheOstat-switch, means to throw these switches to the stop position, means to hold the main switch in the running position, a magnet adapted to hold the rheostat switch in the running position and to release the main switch when the motor-current becomes too strong, and to release the rheostat switch whenever the motor-current dies out.

2. The combination in a motor-starter of a main switch a rheostat-switch, means acting to draw both switches away from the running position, means for holding the main switch in the running position, a magnet connected in the motor-circuit and adapted to act independently on both switches, holding the rheostat-switch in the running position and releasing the main switch whenever the motor-current becomes too strong, but without releasing the rheostat-switch.

3. In a motor-starter the combination of a main switch provided with means for holding it in the running position and means for releasing said holding means, a rheostat-switch, means acting to draw each switch away from the running position, a magnet connected in the motor-circuit and having poles at one end to hold the rheostat-switch in the running position, and poles at the other end that actuate the means for releasing the holding means of the main switch, this magnet being constructed to release the main switch whenever the motorcur rent becomes too strong, without releasing the rheostat-switch, and to release the rheostat-switch whenever the motor-current becomes too weak.

4;. A motor-starter provided with a switch to open the motor-circuit, a switch to cut out the starting resistance, a compound coil-magnet adapted to openthe first-named switch without moving the other switch whenever the current through the motor-armature becomes excessive, and to hold the second-named switch in the running position so long as current flows through the motor.

5. A motor-starter provided with a main switch and a rheostat-switch both of which are controlled independently by a magnet that is energized by two coils, one coil being connected in series with the motor-armature the other coil being connected in shunt relation to the motor-armature.

6. A motor-starter provided with a main switch, a rheostat-switch and a compound coil-magnet to control these switches independently, one of the coils of the magnet being connected inseries with the motor-armature, the other coil being connected in series with the shunt field-coil of the motor.

7. A motor-starter provided with a switch to close the motor-circuit, another switch to cut the starting resistance out of the armature-circuit, a compound coil-magnet to control both switches independently, one of the magnet-coils being traversed by the main motor-current, the other coil being traversed by a current shunted around the motor-armature.

8. In a motor-starter the combination of a main switch means for looking it in the closed position, means to throw it to the open position, a rheostat-switch adapted to be held in the running position by a magnet, means for throwing this switch to the stop position, a magnet energized by two coils one of which is connected in series with the main motorcircuit the other being connected in a circuit that shunts the motor-armature, this magnet being adapted to hold the rheostat-switch in the running position and to unlock the main switch substantially in the manner described.

9. In a motor-starter, amain switch, a rheostat-switch, a toggle-joint lock to hold the main switch closed, means for holding the rheostat-switch in the running position means for throwing both switches to the open position, means for tripping the toggle-joint lock, a compound coil-magnet connected in the circuit in the manner described and adapted to actuate the tripping device and to control the means that hold the rheostat-switch in the running position.

10. In a motor-starter, a main switch and means for holding it in the closed position, a rheostat-switch carrying an armature, means for throwing either or both switches to the stop position, means for releasing the main switch, a magnet adapted to attract the rheostat-switch armature and to actuate mainswitch-releasing device, this magnet being energized by coils connected in the motor-circuit one in series and one in parallel with the motor-armature.

11. In a motor-starter arranged substantially as described, a compound coil-magnet having poles at both ends, the poles at one end acting to retain the rheostat-switch in the running position, the poles at the other end acting to move the tripping mechanism that releases the main switch.

12. In a motor-starter arranged substantially in the manner described, a compound coil-magnet connected in the motor-circuit in the manner described, one of its ends attracting an armature mounted upon the rheostatswitch but electrically insulated therefrom, the other end acting upon the tripping device that releases the main switch.

13. In a motor-starter arranged substan tially as described, with a locking device for the main switch, an unlocking device for opening the locking device, a compound coil-magnet connected in the motor-circuit in the manner described, to actuate the unlocking device, means to oppose the action of the magnet upon the unlocking device and means to vary the magnitude of this opposition.

14. In combination with a motor-starter having a rheostat-switch and a main switch and a locking means for said main switch; the trip-rod 1 1 for releasing said locking means, the guide 19 for said rod, the actuating armature'lever 16 for said rod, and the compound coilmagnet D E, arranged to act on said armature-lever and also directly controlling the rheostat.

15. In combination with a motor-starter arranged in a manner substantially as described with a rheostat-switch and a main switch; a rod 14: arranged to release the main switch, guide 19 for said rod, lever 16 controlling said rod, a magnet l) E, in controllingrelation to the rheostat-switch and to the lever 16, and means to resist the attraction of the magnet for lever 16.

16. In combination with a motor-starterarranged substantially as described with a rheostat-switch and a main switch; a rod 1 1 adapted to release the main switch, guide 19 for said rod, lever 16 connected with said rod, magnet l) E controlling the rheostat-switch and said lever, a spring mounted on rod 1% to resist the attraction of the magnet for said lever, and means for adjusting the tension of this spring.

17. In a motor-starter arranged substan tially as described, the combination of switch B provided with an arm 11, the toggle 12 13, red 14:, guide 19, lever 16, magnet I) E, a re sisting force to oppose the attraction of the magnet for lever 16, and means for varying the magnitude of this opposing force.

18. In a motor-starter arranged substantially as described, a retaining-magnet with its iron parts curved at the upper end and terminating in pole-surfaces substantially parallel with the rheostat-switch when the latter is in the running position.

19. In a motor-starter, the combination of the switches B and C, means for throwing them to the stop position, the rheostat R and contacts V, the magnet I E energized by coils X Y, the locking device 12 13, the rod 1 1, lever 16, guide 19, the spring mounted on 11 and the adjustingnuts 15.

The foregoing specification signed this 6th day of February, 190%1.

IVILLIAM BAXTER, Jn.

In presence of Joim H. PHAIR, STEPHEN H. OLIN.

Images