US1135870A

US1135870A - Motor-starter.

Info

Publication number: US1135870A
Authority: US
Inventors: George H Whittingham
Original assignee: MONITOR Manufacturing Co OF BALTIMORE CITY
Current assignee: MONITOR Manufacturing Co OF BALTIMORE CITY
Priority date: 1911-09-29
Filing date: 1911-09-29
Publication date: 1915-04-13
Anticipated expiration: 1932-04-13

Description

I as,

G. H. WHITTINGHAM.

'MOTOR STARTER.

APPLICATION FILED SEPT-29, 1911.

1,135,870. Patented Apr. 13, 1915.

2 BHEETSSHEET 1. m

lvwewboz G H. WHITTINGHAM. MOTOR STARTER.

APPLICATION FILED snnzs, 1911.

' 1,135,870. Patented Apr. 13,1915.

2 SHEETSSHEBT 2.

LINE

UNITED STATES rATENT OFFICE.

GEORGE E. WHITTINGHAM, OF PIKESVI LLE, MARYLAND, ASSIGNOB TO MONITOR MANUFACTURING COMPANY OF BALTIMORE CITY, OF BALTIMORE, MARYLAND,

A. CORPORATION OF MARYLAND.

MOTOR-STARTER.

Application filed September To all whom it may concern:

Be it known that I, GEORGE H. Wnrr'rme- HAM, a citizen of the United States, residing at Pikesville, in the county of Baltimore and State of Maryland, have invented certain new and useful Improvements in Motor- Starters, of which the followingis a specification.

This invention relates to starters for electric motors of the kind in which the cutting out of the starting resistance is controlled by the quantity of current flowing in the armature circuit.

In carrying out my invention an electrol the pole-piece switch, and

magnetic switch is provided for each section of starting resistance, this switch comprising a series magnet, having its windings in series with the motor armature, a holding magnet having its windings in'a circuit independently of the armature circuit of the motor, and a rocking armature pivoted 'between'its ends and normally biased toward of the series magnet, the arrangement being such that when the motor circuits are first closed the series magnet will hold the rocking armature until the starting current falls to a predetermined amount, when the holding magnet will attract the armature and the switch contacts will be thereby closed and held together with considerable pressure, the holding ma'g-. 1

net operating like a spring to close the switch. when the current is cut off the rocking armature is released from the holding magnet and swings, by gravity, toward the pole-piece of the series magnet, thus opening the switch. a

The invention also includes means for regulating the reluctance, of the -magnetic circuit, to control the time of closure of the means for cutting down the current flow in the holding magnet after the switch has closed, in order to avoid heating of the latter magnet, which, if permitted, would change its resistance relatively to the resistance of the series magnet and therefore change the time of closure of the switch in a subsequent operation.

In the accompanying drawing which illustrates my invention, Figure'*"1 is a front elevation of one ofthe resistance-controlling switches; Fig. 2 is a side elevation of the same partly broken away, the switch being shown in closed position; Fig. 3 is a central Specification of Letters Patent.

Patented Apr. 13, 1915.

29, 1911. Serial No. esaom.

vertical section through the switch, show-.

ing the same in open position; Fig. 4 is an end view of the adjustable pole-piece, with the series coil surrounding the same; and, Fig. 5 is a diagrammatic view illustrating the starter with two steps of starting resistance. .i

Referring to Figs. 1 to 4;,inclusive, of the drawing, A indicates, as a whole, one of the electromagnetic switches for cutting out starting resistance, which is mounted upon a suitable insulating base or panel B, and C indicates an iron frame or base secured to the panel and having projecting therefrom an upper pole-piece c a central pole-piece c and a lower pole-piece 0 The upper polepiece is surrounded by a coil 1 of having considerable resistance, and the fine wire,

lower pole piece is provided with a coil 2, I

of coarser wire and lowvresistance. An iron armature D is pivoted, between its ends, upon a pin 3 passing through ears 4 on the armature and 5on the central pole-piece. The, armature tends to swing by gravity pole-piece 0 but it is normally held out of away from the pole piece 0 and toward the engagement with the latter pole-piece-by a v tubular stop 6, preferably of non-magnetic material," .which surrounds the pole-piece. The pole piece 0 comprises a tubular part 'Z, integral with the base C, and a rod or bolt 8 having a threaded connection with the part 7, the part 8 being adjustable relatively to the stop 6 so that the distance of the pole-piece regulated'to vary the attractive force of the series magnet upon the armature. The belt 8 has one or more slots 8 extending diametrically thimughit thekbolt in the drawing being shown with two such slots. I pin 9 extends diametrically through the tubular stop 6 and through one of the slots 8 in the adjustable pole-piece and therefore locks the latter in its position of ad-' the series coil upon the pole piece,, A cop-s fromthe armature may be A cotter between the pole-pieceand the armature 45 "i then to engage the contact 18 and close the per cross piece 1.0, secured to the upperend of the armature, carries contacts 11, adapted to engage suitable stationary contacts 12 12 and 12 indicate the stationary contactsof such switches, these contacts, in the diagram, being shown above the cross bars in order to indicate the open positions of the switches. The switch for connecting the starter, and the motor M with the supply circuit is indicated at S and the armature circuit of the motor extends from the stationary contact 13 of said switch, through conductor 14:, series coil 2*, and section of starting resistance 15, series coils 2", and section of starting resistance 16, and thence through the'motor armature 17 to the negative supply wire. The coils of the holding magnets of the resistance-controlling switches are in a circuit 19 which extends from a stationary contact 18, on the switch S, through the

holding coils

1 and 1 in series,.and thence through a fixed resistance 20 to the negative side of the supply circuit. The total resistance of the circuit 19 is high, and normally only a small quant'ty of currentpasses through the holding oils of the switches; Another high resistance coil 21 is arranged'so that when the switch A closes this resistance will be connected in series with the resistance 20 and in shunt to the holding coils 1- and 1 the resistance 21 being proportioned so that when thrown in circuit the current flowing through the hold:

ing coils of the switches will be very small in quantity and not sufficient to cause the coils to heat. The supply circuit switch S comprises a pivoted arm 22 adapted, in closing, to first engage the contact 13 and close the armature circuit through the series coils of the resistance-controlling switches, and

circuit 19 through the holding coils of said switches and through the resistance 20. The switch S is represented in the drawing as an electromagnetically-controlled switch, the magnet 23 of which is arranged in a circuit 24, connected at one end to the negative supply wire and a manual-controlled'switch' 25 is provided for connecting the circuit 24 with the positive supply wire. The motor is shown with a shunt field 26, connected at one end to the negative supply wire and having its opposite end connected through conductors 27 and 14 to the contact 13.

In operation, when the manual switch 25 is closed, the magnet 23 is energized and the switch arm 22is attracted thereby and first engages the contact 13 and then engages the contact 18. i/Vhen the contact 13 is engaged current flows through the conductor 27 and the field of the motor and it also flows through the series coils 2*, 2 'and the starting resistance sections 15 and 16' and through the motor armature 17. Thexrock ing armatures D of the switches normally rest against the tubular stops 6, and closer to the pole-pieces of the series magnets than i to the pole-pieces of the; holding magnetsny -Hence these arm'atures will be strongly attracted by the series magnets which carry holding magnets and the resistance 20', andthese magnets also exert an attractive force on the armaturesD, but insuificient to rock the same away from the series magnets so long as the starting current remains above predetermined limits. It will be noted that the projection 0 upon which the armature D of each resistance controlling switch is mounted, is a part of the magnetic circuit of both the series and holding magnets; but the heavy magnetic flux created by the current'in the series coil, when the starting' current 18 a maximum, practically saturates the common pole-piece 0, and by properly connecting the coils the flux created by the series coil may be made to oppose the flux set up by by the holding coil so that while the starting current is 'a maximum the attractive force of the holding coil upon the armature will be small, whereas when thecurrent in the series coil falls this opposition of the magnetic fluxes will be correspondingly reduced force as the current in the series coil diminishes.

In Fig. 3, the dotted lines and arrows s and h indicate the opposing magnetic fluxes set up by the current in the series and holding coils, respectively. When the starting current falls to a predetermined amount, the

and the holding coll Wlll attract with greater.

attractive force of the series magnet 2 of the switch A will be overcome by the attractive iorce of the holding'coil' 1 and the armature will be moved by the latter magnet to close the switch, the bridge piece 10 of which will then connect the

stationary contacts

12 and 12*. Current will then fiow from'the contact 13, through conductors 27 and 28 to the contact 12 thencev through bridgepiece 10 and contact 12 and through conductor 29 to an intermediate portion of the coil 2 of the switch A thence through a portion of said coil and through resistance section 16 to the armature. The series coil 2 of the switch A, the resistance section 15 and a portion of the series coil 2 will then be sho'rtcircuited and the switch A will be held closedby the shunt magnet 1. After the temporary rise in current which follows the'cutting out of this first resistance section, as the motor armature gains speed, the armatureicurrent- I will again fall. When it falls to-a predetercontact 12, bridge-piece l and 12 and conductor 81 to the motor armature, the resistance section 16 and the remaining windings of the series coils 2 being short circuited. The armature D of the switch A will be held closed by the holding coil 1.

As previously stated the total resistance of the circuit 19, including the high

resistance holding coils

1 and 1 and high resistance 20, is such, as compared with the voltage of the supply circuit, that the on rent which flows initially through the lib 'ing coils is small, being only a fraction of an ampere and insuflicient to heat the coils during the starting interval. When the switch Aicloses the high resistance coil 21 is connected in parallel with the holding magnets and in series with the high resistance coil 20. As shown in the drawing the high resistance 21 is connected by the conductor 32 to the wire 19 between the resistance 20 and the holding coil 1 and the opposite end of the resistance coil 21 is connected by a conductor 33 to the armature D of the switch A. It will be seen that as soon as the switch A closes the conductor 33 will be connected "through the bridge piece 10 to the contact 12 and thence through conductors 30, 27 andl l to the contact 13 and thence through the switch arm 22 to the positive supply wire. Thus the limited quantity of current passing through the resistance 20, becomes divided between the circuit 19, which includes the holding coils, and thecircuit which includes the resistance 21-and the current flowing through the holding coils will be reduced to a very small quantity, but sufiicient to hold the switches in their closed. positionswith firm contacts. Whenever the manual switch 25 is opened, it will be evident that the switch S will be released by its magnet 23 and the motor circuits will thereby be opened and the armatures I)' will fall by gravity away from the holding

magnets

1 and 1 toward the series magnets, thus causing the starting resistance to be reinserted in the armature circuit of the motor. In this switch it is important to prevent heating of the holding coils, as an increase in resistance due to heating would prevent "be no mal current from flowing through the coils of the holding magnets, in starting, and hence would decrease the' attractive power of these magnets, and destroy-the adjustment, since the time i of closure of the switches is controlled by the relative attractive forces of the holding and series magnets.

For convenience, the magnets having their windings in series with the armature of the motor will be referred to in the claims as series magnets, and the magnets having their windings in a circuit independent of the I armature circuit will be-referred toiasholding magnets. i

What I claim is l. The combination'with an electric motor and its circuits, including a starting resistance in the armature circuit thereof, of a switch for cutting out said resistance com:-

prising a rocking magnetizable arm, pivoted between its ends, for opening and closing the switch contacts, two'magnets having stationary pole pieces arranged adjacent said rock-' ing arm on opposite sides of its pivotal axis and adapted to oppositely attract the arm,

one of said magnets having low resistance windings in series with the motor armature and the starting resistance and the other having high resistance windings'in a-separate circu t, said arm being'biased to'ward the former "magnet, and means for opening and closing the circuits through said magnets,

2 The combination with an electric motor and its circuits, including a starting resistance in the armature circuit thereof, of a switch for cutting out -said resistance comprising a-rocking magnetizable arm, pivoted between its ends, for opening and closing the switch contacts, tw'o magnets having stationary pole pieces arranged adjacent said rocking arm on opposite sides of its pivotal. axis and adapted to oppositely attract the arm, one of said magnets having low resistance windingsv in series with the motor armature and the starting resistance'and the other having high resistance windings in1aseparate circuit, said arm being biased toward the former magnet, means for varying the relaictarice of the magnetic circuit through one of said magnets and said arm,

and means for opening andclosing thecircuits through said magnets.

3. The combination with an electric motor and its circuits, including a starting resistance in the armature circuit thereof, of a switch for cutting out said resistance comprising a rocking ma gnetizable arm, pivoted between its ends, for opening and closing the switch contacts, two magnets having station- I my pole pieces arranged adjacent said rock-' ing arm on opposite sides of its pivotal axis and adaptedto oppositely attract the arm, one of said magnets having low resistance windings in series with the motor armature and the startin resistance and the other.

having high resistance windings in a separate circuit, said arm being biaseditoward the former, magnet, means for varying the reluctance of the magnetic circuit through the coreof'the magnet having low resistance windings and said arm, and means for opening and closing the circuits through said magnets.

, windings in series withthe motor armature 4. The 'c ombination with an electric motor and its circuits, including a starting resistance in the armature circuit thereof, 01' a switch for cutting out said resistance comprising a rocking magnetizable arm, pivoted between its ends, for opening and closing the switch contacts, two magnets having stationary pole pieces arranged adjacent said rock- .ing arm onnopposite sides of its pivotal axis and adapted to oppdsitely attract the arm, one of said magnets having low resistance and the starting resistance and the other having high resistance windings in a sepa rate circuit, the core of the magnet having low resistance windingsbeing adjustable in length and said arm being biased toward said magnet, a stop for limiting the movement of the arm toward the latter core, and means for opening and closing the circuits through said magnets.

5. The combination. with an electric motor and its circuits, including a starting resist-- ance in the armature circuit thereof,'of a switch for cutting out said resistance com prising a magnetizable arm pivoted between its, ends to rock in a vertical plane, two,

magnets having stationary pole pieces arranged respectively above and below the axis of said arm and adapted to oppositely attract the arm, the lower magnet having low resistance windingsin series with the motor armature and starting'resistance, and the upper magnet having high resistance windings in a separate circuit, said arm being biased toward the lower magnet, and means for opening and closing the circuits through said magnets.

' 6. 'llhe combination with an elecfiic motor and its circiiits, includingv a starting resistance in the armature circuit thereof, act a switch for cutting out said resistance comprising a magnetizable arm pivoted be can its ends to rock in a vertical plane,; two magnets having stationary pole pieces arranged respectively above and below the axis on said arm and-adapted to oppositely attract the arm, the lower magnet having low resistance windings in series with the motor armature and starting resistance, and the upper magnet having high resistance windings in a, separate circuit, said arm being biased toward the lower magnet, means for varying the reluctance of the magnetic circuit through the lower magnet and said arm, and means for opening and closing the circuits through said magnets.

7. The combination with an electric niotor and its circuits, including a starting resistance in the armature circuit thereqflof a switch forcutting out said resistance comprising amagnetizable arm pivoted between its ends to rock in a vertical plane, two magnets having stationary poleipieces arranged respectively above and below the axis of said arm and adapted to oppositely attract the arm, the lo'wer magnet having low resistance windings in series with the motor armature and starting resistance, and the upper magnet having high resistance windings in a separate circuit, said arm being biased toward the lower magnet and the core of said lower magnet being adjustable in length, a stop for limiting the movement of the arm toward the latter core, and means for opening and closing the circuits through saidv magnets. i

8. The combination with an electric motor and its circuits, including a starting resistance in the armature circuit thereof,.of a switch for cutting out said resistance comprising a magnetizable arm pivoted between its ends to rock in a vertical plane, two magnets having stationary pole"pieces arranged respectively above and below theaxis of said arm and adapted to oppositely attract the arm, the lower magnet having low resistance windings in series with the motor armature and starting resistance, and the upper magnet having high resistance windings in a separate circuit, said arm having a fixed range of movement and the'core of the lower magnet being adjustable to vary the reluctance of the magnetic circuit through said latter core and said arm, and means for opening and closing the circuits through said magnets.

The combination with an electric motor and its circuits, including a starting resistance in the armature circuit thereof, of means for cutting out thestarting resistance comprising switch contacts, a base of magnetizable material having a central and two end pole pieces, a magnetizable switch arm for opening and closing the switch contacts, said arm pivoted between its ends on the central pole piece, low resistance windings in series with the motor armature and the starting resistance .on one end pole piece, high resistance windings in a separate cir- 1'10 cuit on the other end pole piece, said arm being biased toward the pole piece having the low resistance windings, and means for opening and closing the circuits through the windings of said magnets.

10. The combinationwith an electric m0- tor and its circuits including a starting re sistance in the armature circuit thereof, of means for cutting out the starting resistance comprising switch contacts, a base of mag 12 netizable material having a central and two end polepieces, a magnetizable switch arm for opening and closing the switch contacts, said arm pivoted between its ends on the central pole piece, low resistance windings Z in series with the motor armaturcand the starting resistance on one end pole piece, high resistance windings in a separate circuit on the other end pole piece, said arm h'aving a fixed range of movement and being 130 biased toward the pole piece having the low resistance windings, and said I latter pole piecev being adjustable tovary the reluctance of the magnetic circuit through said latter pole piece and said arm, and means for opening and closing the" circuits through the windings of said magnets.

- 11 Switch members and means for controlling the same comprising relatively high and low resistance magnets, an armature biased toward the low resistance magnet and adapted to close the switch when moved t0- ward the high resistance magnet, an external high resistance normally lll'SGllQS with the high resistance magnet and another external 15 high resistance adapted to-be included in series with the first mentioned high resistance and in parallel with said high resistance magnet when said switch closes.

In testimony whereof I aliix my signature 2 in presence of two witnesses. GEORGE H. WHITTINGHAM.

Witnesses:

HERTHA ERN$T, CARL W. HAMILL.