US1715377A - Motor controller - Google Patents

Description

June 4, 1929.

N. L. MORTENSEN MOTOR CONTROLLER Orig i nal Filed July 27, 1925 J g 5 [N VIM/TOR 5 A TTORNEY Patented June 4, 1929.

PATENT OFFICE.

UNITED STATES NIELS Ll. MORTENSEN, 0F MILWAUKEE, WISCONSIN, ASSIG'NOR, BY MESNE ASSIGN- MENTS, TO CUTLER-HAMMER INC., 0]? MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE.

MOTOR CONTROLLER.

Application filed July 27, 1925, Serial No. 46,197.

This invention relates to controllers for electric motors.

The invention is particularly applicable to controllers of the character disclosed in the application of Clarence T. Evans, Serial No. 559,187, filed May 8, 19:22, and renewed August a, 1924. r

The controller disclosed in the aforesaid application includes a plurality of accelerating switches, each having a restraining winding associated therewith and an inductor for supplying the restraining windings of said switches with inherently transient currents to delay operation thereof. The delay in closure of the accelerating switches is largely dependent upon the design of the inductor and in practice it has been found that if the inductor is designed to provide longer delay in closure of the first accelerating switch upon plugging than upon starting of the motor from rest, the delay in closure of the other accelerating switches will be influenced to a large extent by the accelerating current and by the load on the motor.

The present invention has among its objects to provide a plugging controller of the character disclosed in the aforementioned application in which the delay in closure of the first accelerating switch is influenced to a large extent by the relation between the line voltage and the C. E. M. F. of the motor armature, while each of the other accelerating switches is adaptedto operate after a given period of delay, which is uninfluenced by the relation between the line voltage and the C. E. M. F. of the motor armature.

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

The accompanying drawing 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 appended claims.

In the drawing: 7

Figure 1 is a diagrammatic view of a preferred form of the controller.

2 is a simplified diagram of the motor connections and the control circuits shown in Fig. 1. I

Referring to Fig. 1 the controller is employed in connection with a direct current motor having an armature A, a series field winding F and a shunt field winding F, it

Renewed October 25, 1928.

being understood that the motor may be of any other preferred type.

The controller includes an electro-responsive main switch 1 and electro-responsive reversing switches, 23 and 45, for establishing reverse power connections for the motor between lines L and L through starting resistances R R R and R in series it being understood that the main switch and reversing switches may be replaced by double pole switches and that any number of starting resistances ma be employed. troller includes resistance control switches 6, '7, 8 and 9 for shunting resistances R R R and R", respectively.

Each of the resistance control switches is of the two magnet type, the same being provided with a shunt operating winding X and a restraining winding Y. The shunt operating windings of the several resistance control switches are arranged tobe connected in par allel between lines L and L by a master switch S, and said master switch, as hereinafter set forth, also serves to control the energizing circuits of main switch 1 and reversing switches 23 and 45. All of the resistance switches tend to respond upon completion of the motor circuit, but each of such switches has its restraining winding normally energized to prevent response thereof.

More particularly, each of the switches 7, 8 and 9, as shown, has its restraining winding connected in parallel with the resistance controlled by the preceding switch, and each of such restraining windings is so proportionedrelatively to its respective parallel resistance, that the voltage drop across the latter when included in series with the motor, will insure adequate energization of the former for holding out action thereof. Accordingly, response of each of the switches 7, 8 and 9 is positively prevented until closure of the preceding switch to shunt the step of resistance paralleling its respective restraining winding whereby sequential operation of the accelerating switches is insured without requirement of the usual interlocking contacts. In this connection it is to be noted that the restraining windings of the switches 7, 8 and 9,1nay be connected in series with the resistances R R and R respectively to the same end, but the arrangement described is preferred where the motor current is of relatively high value.

Also the con- Also the restraining windings Y of the several resistance control switches are subtween main switch 1 and switch 6 and the restraining winding of the latter switch is connected in parallel with said coil. Winding 11 is connected between main switch 1 and switch land the right hand terminal of resistance R is connected to an intermediate tap on said coil. A portion of winding 11 is thus subjected to the initialsu'rge in motor currentupon completion of the motor current and in consequence induces a current in winding 10, whichis supplied to the restraining winding Y of switch 6. The transient current thus supplied to the restraining winding of switch 6 will elfect a delay in the response of said switch.

'Closure of switch 6, as more clearly shown in Fig. 2, connects the motor armature across line L1 L2, through the inductor coil 10 and resistances B2B and R, in series, thereby shuntingthe resistance R and the portion of inductor coil 11, which is included between said resistance R and switch 1. Thus, closure of switch 6 tends to de-energize the restrain ing winding of switch 7, which parallels resistance R but due to. the inductive effect of coil 11 the supply of current to said restrainling winding ismomentarily maintained and .111 the meantime the inductor coil 10, which 18 wound oppositely to the coil 11, induces a current in the latter winding, which further tends to maintain said restraining winding energized. Accordingly, switch 7 is prevented from responding until the current thus induced in its restraining winding is reduced to a given value. 1 I

In this connection, it should be noted thatclosure of switch '6 subjects inductor coil. 10 to a current, increasing from zero value, whereby the transientcurrent induced and supplied to therestraining winding Y of switch 7', insures a definite minimum delay in responseof such switch, irrespective of the peak in motor current incident to inclusion of resistance R On the other hand the peak in notor currentdue to exclusion of resistance R tends to prolong the period of delay in release of switch 7, but the eifect of such peak in motor current is necessarily transient thus precluding the possibility of arrestof switch 7 for any protracted period.

. "Switch 7, in closing connects the motor armature across lines L L through the in- V ductor coil 11 and'resistances and E 'in series, thus shunting resistance R and induc- I tor coil 10 and consequently tending to release switch 8 for response-thereof. However,

the-inductor functions as above described,

but in a reverse manner to maintain the re straining wlnding Y of switch 8 energized for a given minimum period, subject to a slight increase as described in connection with switch 6.

Closure of switch 8 connects the motor across lines L .L through inductor coil 10, switch 6 and resistance R thus shunting the resistance R and inductor coil 11 and consequently tending 'to release switch 9 for response thereof. On the other hand the in ductor is again caused to function as described but with its winding 10 acting as a primary thereof to maintain restraining winding Y of switch 9 energized for a given minimum period subject to aslight increase as described in connection with switches 6 andZ. Closure ofswitch 9 connects the motor across lines L -L through conductor coil 10 and switches 6 and 8 thereby shunting all of the starting resistance.

Upon plugging of the motor all of the resistance switches drop out prior to establishment of reverse power connections for the motor and upon establishment of such reverse power connections, resistances R to R are included in series with the motor together with the portion of inductor winding 11- which is connected between the right hand terminal of resistance R and switch 1. lVhen the motor is plugged at full speed its C. E. M. F. is in the same direction and of substantially the same value as the line voltage impressed upon its armature. The current flow through the motor with all of its starting resistance in series is therefore substantially twice the current which flows when the motor is startedfrom rest. The inductor is designed so that the portion of coil 11 which is connected between resistance R and switch 1 is insufiicient to effect saturation of the core member'12' when starting from rest, and in practice it has been found that due to this fact the current indu'cedin winding 10 will be a. function of the relation between the line voltage and the C. E. M. Ffof the motor armature whereby a longer period. 0t delay will be obtained in closure of the first acshould be noted that due to inclusion ofthe inductor coil 10 in the motor circuit upon eX- clusion offal] the resistance, reversal of the fiuX of said winding will be obtained upon plugging of the motor. Such reversal ofthe flux ofwinding 10 tends to augment the delay in closure-of switch 6 under plugging conditions.

Following closure of and 11 as above set forth act alternately to supply transient currents to the several restraining windings. The ampere turns of each of the windings 10 and 11 are suificient to effect saturationof the core member of in ductor I under current conditions corresponding to starting of the motor under light loads and in practice it has been found thatby deswitch 6 windings 10 signing the inductor windings in this manner the period of delay in closure of the resistance control switches 7 8 and 9 will be sub stantially constant for both heavy and light loads.

As before stated, a master switch S is provided for controlling the energizing circuits of main switch 1, reversing switches 23 and 4 5 and the resistance control switches 6 to 9, inclusive. The master switch S includes a series of stationary contacts 14 to 18, inclusive, and two sets of movable contacts arranged on opposite sides thereof. One set of movable contacts includes electrically connected contacts 14, 15, 16 and 1S, and the other includes electrically connected contacts 1 1, 15, ll and 18 Upon movement of the master switch towards the right, the left hand set of movable contacts is connected to line L through contact 14;, and main switch 1 is then energized through the medium of contacts 15 and 15; reversing switches 2 and 3 are energized through a medium from contacts 16 and 16, while the operating windings X of switches G to 8, inclusive, are energized through the medium of contacts 18 and 18" and auxiliary contacts 2". Upon movement of switch S towards the left, the right hand set of movable contacts is connected to line L through contact 1 and main switch 1 then energized through the medium of contacts 15 and 15"; reversing switchesd and 5 are energized through the medium of contacts 17 and 17 while the restraining windings X of the switches 6 to 8 are energized through the medium of contacts 18 and 1.8" and auxiliary contacts 5 The control means still further includes a jamming relay 19 arranged in the energizing circuit of switches 6 to 8 inclusive. Relay 19 is normally closed and has an operating winding 19 included in series in the motor circuit. Under given overload conditions in the motor circuit, relay 19 responds to interrupt the energizing circuit of all of the operating windings X of resistance switches 6 to 8, inclusive.

,VVhat I claim as new and desire to secure by Letters Patent is:

1. In a motor controller, in combination, accelerating means and means to arrest for temporary periods the accelerating action of the former means in different stages thereof,

the latter means including a plurality of windings arranged in an inductive relation, and each to be included in the motor circuit in certain of said stages, and means for varying the mutual inductance of said windings in certain of said stages.

2.111 a motor controller, in combination, accelerating means and means to arrest for temporary periods the accelerating action of the rormer means in different stages thereof, the latter means including a plurality of windings arranged in an inductive relation,

and commutatable connections providing for inclusion of each of said windings 1n the motor circuit in certain of said stages, and for variation of the mutual inductance of said the former means in different stages thereof,-

the latter means including inductive windings adapted to act alternately one upon the other in successive stages of acceleration, and

means associated with one of said windings to provice for differentiation of the condi tions under which the action of the first men tioned means is arrested in different stages thereof.

1. in a motor controller, in combination, accelerating means and means to delay for temporary periods the accelerating action of the former means in different stages thereof, the latter means including inducthe windings adapted to act alternately one upon the other in successive'si ages of acceleration, and means associated with said windin s to provide a variable delay in certain of said stages and a substantial ly uniform delay in the other of said stages.

5. In a motor controller, in con'ibination, acelerating means and means to delay for teml'iorary periods the accelerating action of the tormer means in dill'erent stages thereof, the latter means including inductive windings adapted to act alternately one upon the other in successive stages of acceleration, and means associated with said windings to provide a variable delay in certain of said stages and a substantially uniform delay in the other of said stages, said former delay being a function of the relation between the C. E. M. F. of the controlled motor and the supplied voltage.

6. In a motor controller, in combination, accelerating means and means to arrest for temporary periods the accelerating action of the former means in different stages thereof, the latter means including windings arranged in an inductive relation, and comvmutatable connections for said windings to cause the same to act alternately, one upon the other, as the accelerating action of the first mentioned means progresses, said connections providing for influence of one of said windings by a portion of the other in certain of said stages and for influence of the former winding by all of the latter winding in other of said stages. v

7. The combination with a motor and a supply circuit therefor of accelerating means for the motor, means to arrest for temporary periods the accelerating action of the former means in different stages thereof, the latter means including windings arranged in an. inductive relation, and commutatable connections for said windings to cause the same -tor from said supply circuit, a plurality of accelerating switches operable sequentially, said switches having indivldual restralning coils, and means for supplylng said restraining coils with inherently transient currents to delay operation of said switches, said latter means being adapted to subject the restraining winding ofthe first accelerating switch to a transient current, which is a function of the relation between the voltage of the supply circuit and the C. E. M. F, of

themotor,,and to subject the other restraining windings to transient currents of a given value under variable current conditions in the motorcircuit. V

9. In combination, a motor, accelerating means therefor, means including a pluralityof windings arranged in a mutually inductive relation, to arrest the accelerating action of the former means indifferent stages and commutatable connections subjecting said windings alternately to motor current as acceleration progresses and including 1n the motor circuit for different stages of acceleratron different numbers of turns of one of said wlndmgs.

10; In combination, a motor, reversing and accelerating means'therefor, means including a plurality of windings arranged in a mutually inductive relation, to effect arrestof the accelerating action of the former means in different stages, and commutatable connections for said windings subjecting the same alternately to motor current and encludingfrom circuit for the first stage of acceleration, a part of the winding subjected to the motor current. V

11. In combination, a motor, reversing means therefor, accelerating means for the motor and means controlling said acceleratthereof in different stages, said last mentioned means comprising windings arranged in amutually inductive relation and controlled by said accelerating means to be subjected to the motor current alternately asthe acceleration of the motor progresses and further controlled by said accelerating means whereby the winding first subjected to the motor current is in part excluded from circuit for the first step of acceleration. V In witness whereof, I have hereunto subscribed my name.

NIELS L. MORTENSEN! ing means to arrest the accelerating action

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