US1365322A

US1365322A - Control system

Info

Publication number: US1365322A
Application number: US264931A
Authority: US
Inventors: Henry D James
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1918-12-02
Filing date: 1918-12-02
Publication date: 1921-01-11
Anticipated expiration: 1938-01-11

Description

H. D. JAMES.

CONTROL SYSTEM.

APPLICATION FILED DEC.2, 1918.

1,365,322. Patented Jan. 11, 1921.

LLCAOUICM/WM 2 L oc%ouzCan/ac/ 5rs 6' g l8 /9 ia g 7 T G: 5 minr L J 1 WITNESSES: Lac lgmufaonfiac 70m q INVENYTOW KQ Hen/" Una/mes.

{ MW ATTCiRiW I HENRY 1). JAMES, 0F EDGEVJQQD PARK, PENNSYLVANIA, ASSIGNOR TQ WESTING- H0'USE MECTRIG 6a MANUFACTURING- CQItILANY, A GQYEQPOEATIQN @F EENNSYL- VANIA. CQN'TPRQL SYQaTEIE.

gfig ggg S iccification of Letters Patent. Patented Jam, 111 1921,

application .filed'ficceniber 2;, 1918. Serial No. 284,931.

To all whom it may concern."

Be it known that T, Hnnnr lD. JAMns, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Control Systems, of which the following is a specification.

My invention relates to motoncontrol sys tems, I

The object of my invention is to provide a control system with the aid of which it shall be possible to start a motor, to accelcrate it and to control its speed in accordance with predetermined condit ons.

According to my invention, an acceleratingv resistor is short-circuited by means contactors of the now well known loch out type having the peculia property being maintained open cu-rent is above a predetermined value and of closing when the current falls to value. I connect the actuating coils of the contactors between different-potential points'ci the sow ing resistor. As the coils become deenergized when the starting resistor is short-circuited, it is necessary to provide some means for maintaining the resistor 'short-circuited. In one form of my invention, T e est this re sult by energizing; the last contactor to close by the electrornotive force of the motor. According to another form of nay invention, the actuating coil of the contactcr, or plurality of the contactors may, afterclosing, be connected directly across the line.

My invention will be made clear nection with the accompanyir j which Figures 1, 2 and 3 are representations of different vention.

Referring to Figs. 1 and 2, electric rnotor, having; an armature 1 and e shnnt lield= magnet winding 2, is connected between line conductors 3 and l, separated by a line con= tactor 5, which is adapted to he closed hy means of an actuating coil 6, the circuit ct which may be closed by a master switch 7 An accelerating resistor, portions of which are indicated at 8, 9-and 10, is connected in series with the armature 1 and adapted to be short-circuited by a plurality of

contactors

11, 12 and 13, having actuating

coils

14, 15 and 16.

The contactors 11 and 12 of Fin/ 1 are ot the lookout type; that is, when the current flowing through their actuating coils is above a predetermined value, they will be maintained in the illustrated, open positions; and whenthe current falls to this value, they will close. The contactor 13 of the system of Fig. 2 is, like the contactors 11 and 12, a lookout contactor.-..but the circuit of its coil 16 is connected, in series with a resistor 17 of high resistance, across the line conductors 3 and l.

Tn Fig. 1, the actuating coils I l and 15 of the contactors 11 and 12 are connected at 18 19, in parallel, acrossthe accelerating resistor. The contactor 11 of Fig. 2 is connected, 19 and 20, between one end of the resistor and the point connecting the no? ticns 8 9.05 the resistor, and the contactor 15 is connected at 18 and 19, across the whole resistor. The contactor 13 of F is adapted to bridge contact members 21, when occupying open position, for the purpose of then closing a circuit for its ac tuja'ting coil 16-, which extends from the point 18, through the contact members and the coil 16, to the point 19. i

The operation of the system shown in 1 may be described as follows. Assuming that the master switch 7 has been closed to cause the energization of the coil 6, and thereby to cause the closing of the contactor 5, current will flow from the line conductor 3, through the armature 1 and the accelerating

resistor

8, 9, 10, and the shunt field magnet winding 2, inparallel, to the point 19 and thence, through the line contactor 5, to the line conductor 4*. A shunt circuit is, at same time, established for the will serve maintain the contactor 12 open eriod of tune until for predetermined the current again ital s, this time to the closing value of the contactor12. The closing of this contactor results in short-cirtill pin

tactors 11 and 12, since they are controlled by the potential difference of the

points

18 and 19. This has no result upon the operation of the motor, however,because of the contactor 13, which will remain closed so long as the counter-electromotiveforce of the motor is above a predetermined value.

If the motor-be started under a moder ately heavy load, the current will fall so rapidly from a high value to a value below that at which the contactor 11 is adapted to be closed that this contactor will remain open. The

contactors

12 and 13, however, will close in order, as above described. Similarly, if the motor be started under a light load, the starting current may drop from a high value to a valuebelow that at 'which the contactor 12 is designed to close with the result that the contactors '11 and 12 will remain open and the accelerating resistor will be controlled entirely by the counter-electromotive-force contactor 13.

I thus provide a system having the requisite kinds of speed control adapted to the load on the motor.

The operation of the system of Fig. 2 is somewhat different, for thetime of closing of the contactor 11 is controlled, not merely by well known adjustments of the contactor itself, but also'by the fact that its coil 14 is connected across a portion only of the accelerating resistor. The contactor 11 will, accordingly, close, before thecontactor 12, to short-circuit the resistor portion 10.

Upon the closing of this contactor 11, the coil 15 will be controlled by the potential difference between the. point 18 and the point 22, which latter point separates the

resistor portions

9 and 10, the resistor portions having been short-circuited by the of the contactor 11. The contactor l2 wil then close at the proper time, in accordance with current conditions. as described in connection with the description of Fig. 1, to short-circuit the resistor ortion 9. The coil 16 will now be controlled by the difference of potential between the

oints

18 and 20 and, when the contactor 13 nally closes to short-circuit the resistor portion 8, the circuit of the actuating coil 16 will be broken at the contact members 21 but the coil will continue to be energized by the circuit extending from the line conductor 3 through the resistor 17 and the coil 16, to the point 19 and thence, through the contactor 5,.to the line conductor 4. This circuit, though not sufiiciently energized to cause the actuation of the contactor 13 in the first instance, will maintain the contactor in closed position.

It will be obvious that the

contactors

11, 12 and 13 of the-system of Fig. 2 may be connected in parallel, as isthe case with the contactors 11 and 12 of Fig. 1, and that the latter co'ntactors may be connected to different intermediate points of the accelerating resistor, as in Fig. 2.

It will be obvious, too, that the contactor 13 of Fig. 1 may be replaced by a contactor like that numbered 13 in Fig. 2. The circuit of each of the coils 1 1, 15 and 16, in that event, since they will be all connected in parallel, and including contact members like those numbered 21 in Fig. 2, will be closed when the contactor 13 occupies its open position. This is diagrammatically represented in Fig. 3 in a system employing but two contactors. Other modifications, too, will occur to those skilled in the art, and I desire, therefore that the a)- pended claims shall be construed broadly except in so far as limitations may be expressly imposed therein.

I'claim as my invention:

1. The combination with an electric motor and a resistor in circuit therewith, of a plurality of switches for controlling said resistor, one of said switches havingv lockout characteristics and another of said switches being so connected as to close in accordance with the value of the current traversing said motor and to be thereafter responsive to the value of the counter-electromotive force of said motor.

2. The combination with an electric motor, of means for'controlling the same comprising a starting resistor, a plurality of electromagnetic switches for controlling the resistor which hold open when the energizing current is relatively high and close when the current decreases to a lower value, and connections whereby the energizing winding of one switch is connected between points of different potential of said resistor to cause it to close when the current through the resistor decreases and the winding of another switch is thereupon effective to control said other switch.

3. The combination with an electric motor, of means for controlling the same com prising a starting resistor, a plurality of electromagnetic switches for controlling the resistor which hold open when the energizing current is relatively high and close when the current decreases to a lower value, each having an energizing coil adjusted and connected between points of different potential of said resistor to cause them to successively close as the current through the resistor decreases.

4. Thecombination within electric motor having a resistor associated therewith, of a pair of electromagnetic switches for controlling said resistor which hold open when the energizing current is relatively high and close when the current decreases to a lower value, one of said switches having an actuating coil connected between points of different potential of said resistor, and the other of said switches having a coil that is energized to maintain said other'switch closed during the normal operation of said motor.

5. The combination with an electric motor having a resistor associated therewith, and a source of energy for said motor, of an electromagnetic switch for controlling said resistor which holds open when the energizing current is relatively high and closes when the current decreases to a lower value and having an actuating-coil connected 'between points of different potential of said resistor, and means for energizing said coil by energy from said source to maintain said switch closed llp0n the closing of said switch.' 1

6. The combination with an electric motor having a resistor associated therewith, of a plurality of electromagnetic switches for controlling said resistor which hold open when the energizing current is relatively high and close when the current decreases to alower value, each having an actuating coil connected across different portions of said resistor, and connections whereL y, upon the closing of one of said switches, a portion of said resistor, across which the coil of another of said switches is connected, 5s short-circuited. 4

7. The combination with an electric motor having a resistor associated therewith, of a switch, for controlling said resistor which holds open when the energizing current is relatively high and closes when the current decreases to a lower value, and having an actuatlng coil connected between polnts of different potential of said resistor and another switch for controlling said resistor having an actuating coil responsive to the counter-electromotive force of said motor.

In testimony whereof, I have hereunto subscribed my name this 27th day of Nov.,

HENRY D. JAMES.