US940550A - Apparatus for starting electric motors. - Google Patents

Description

S. B. PAIN'E. APPARATUS FOR QTABTING ELECTRIC MOTORS. APPLICATION, PIL D HAY 2a, 1909.

940 55 0. Patented N0v.

Witnesses:

Inventor Sidney B. Paine,

may.

lil-

6, switch losing connected in series SIDNEY B. PAINE, Q NEWTON, IiidSSACE'USETTS, ASSIGNOR T0 GENERAL ELECTRIC GQEIPANZ, CORPORATION OF NEW! YORK.

WPABATU$ 'E'QR STARTING- ELECTRIG MOTORS.

Specification of Letters Eatent.

Patented 31 d,

application filed May 28, 1969. serial lilo. 498,948.

VMassachusetts, have invented certain new and useful lmprovements in Apparatus for Starting Electric Motors, of which the following is a specification.

My invention relates to the starting of a plurality of electric motors, and has for its object on improvement in the apparatus used in such a connection.

ll accomplish the object of myinvention by the employment of certain forms of apparatus and connections pertaining thereto, the novel features of my invention being pointed out with more particularity in the claims annexed to and forming a part of this specification. 4 For a further understanding of my invention reference may be had to the accompanying drawing, which shows diagrannnatically the connections and apparatus which I employ.

1 is a source of voltage which is illustrated as bein a three-phase'generator connected by con uctors 2 to a suitable/switching device 3, which is shownas being of the usual type of starting compensator employed with induction motors. Conductors i, 5 and 6 are shown also connected to this starting device, the starting device being connected between the source and the conductors. The essential features of this starting device consist of a plurality of movable contacts 7, which may he made to engage with stationary contacts 8 and 9. When contacts 7 are in connection with contacts 8, conductors l, 5 and 6 are energized from a portion of the voltage of the source; this being accomplished by suitable compensator windings 10, which are connected across conductors 2 and have connected to them ta 5 11 which energize conductors d, 5 and 6 in the well known manner. When contacts 7 are in contact with contacts 9, the conductors l, 5 and 6 are energized from full voltage from the source, loses 12. losing placed in serice with these conductors in the usual man'- ner. p

A plurality oi motors 13, as shown, are connected in parallel to conductors d, 5 and lac-tween motor and the conductors, These switches are diagraminaticaldv illus rated as being of the usual oil-insulatedtype, and have in connection with them an electromagnetic under-voltage tripping device which consists of a coil 15, and tripping device 16, which, in conjunction with theusual mechanism, not shown, opens switch ll when the voltage across coils 15 is lower than a predetermined amount. Connected in series with coil 15 is shown a resistance 17, the coil and resistance being connected by conductors 18 to conductors 2,- either directly as shown or through a suitable transformer. Thus, 'l'he energization of these coils will be independent of the position of the starting device 3. @ondactors 18 are shown having placed in 'sc 1 1 for purposes of oat w placed in series wr In addition to the undo gs til, devices, in connection with switches 1% are also shown overload tripping devices 20. These devices consist of a magnetic core which will be raised when a current above a predetermined amount flows in coil 22,

shown in operative relation with core 21,

and is connected in series with one of the phases of the 'circuits leading to the motor. When the core' has been raised a certain amount contact 23 will make contact-with contacts 24 and thus short circuit coil 15 of the under-voltage tripping device, and cause the switch ll to open. In operative relation with movable core 21 is shown a dashpot mechanism 25, which retards the 1110- tion of the overload device so that it will require-a considerable period of time before-it makes contact with contacts 24:" The object of this mechanism is that when an induction motor is starting, it requires a current considerably in excess of the usual current which it takes when running. If the overload tripping devices are adjusted to be actuated slowly and not instantaneously when the motors are started with such excessive current as would normally cause these devices to be actuated, their movement is adjusted so as to be of such slow nature that there will not he suflicient time for them to trip the oil switches before the heavy starting current becomes reduced through the speeding up of the mot-01's.

- The operation of my apparatus will then be as follows Nhen it is desired to start up a plurality of motors the under-voltage by Letters Patent of the United States is,-

tripping devices are connected up as shown, so that in case the voltage from the source is below normal, switches 14 will be open and it will be impossible to start motors 13. The starting device 3 is then placed in such a position'that Contacts 7 are in connection with contacts 8, and conductors 4, 5 and 6 are, therefore, energized with a portion of the voltage from the source. The motors will start up with a currentin excess of the normal running current and. the overload devices 20 will begin to be actuated, but their movement will be. comparatively slow, because of the action of the dash-pot mechanism 25. After the motors have speeded up the usual amount, switching device 3 will be so operated that contacts 7 are in connection with contacts 9 and the motors will be energized with the full voltage from the source. The current flowing in the coils of the overload tripping devices will be greatly diminished and the cores of these devices will tend to move downward due to the action of spring mechanism, not shown. The running conditions will now prevail for the motors. If the voltage on the line decreases below a certain amount, oil switches 14 will be opened and if an overload occurs on any motor, the switch in series with it will be opened to the action on' the overload tripping device.

WhileI have shown my invention as applied to a certain form of apparatus and connections therefor, it is obvious that a number of such forms and connections will be obvious to those skilled in the art, and I seek in the appended claims to cover all such forms and connections which will be in the spirit of my invention. a

What I claim as new and desire to secure 1. In a system of distribution, a sourceof voltage, a plurality of conductors, a starting device connected between the source and the conductors for simultaneously energizin the conductors alternately with a portion 0% the voltage'from the source and with full voltage from the source, a plurality of motors connected in parallel to the conductors, switches connected in series between the motofs and the conductors, overload tripping devices for the switches, under-voltage electromagnetic tripping devices for the switches and conductors connecting said tripping devices to the source independently from the starting device.

2. In a system of distribution, a source of voltage, a plurality of conductors, a compensator connected between the source and the conductors adapted in one position to energize the conductors with a portion of the voltage from the source and in another position with the full voltage from the source, a plurality of motors connected in parallel to the conductors, switches connected in series between the motors and the conductors, undervoltage electromagnetic tripping devices for the switches, conductors connecting said tripping devices to the source so as to be independent of the position of the compensator, and means operative upon an overload for actuating said tripping devices.

3. In a system of distribution, a source of voltage, a plurality of conductors, a compensator connected between the source and the conductors adapted in one position to energize the conductors with a portion of the Voltage from the source and in another position with the full voltage from the source, a plurality of .motors connected in parallel to the conductors, switches connected in series between the motors and the conductors, under-voltage electromagnetic tripping devices for the switches, conductors connecting said tripping devices to the source so as to be independent of the position of the compensator, and means operative upon an overload to short-circuit said v tripping devices after a predetermined time.

In witness whereof, I have hereunto set my handthis 26th day of May 1909.

SIDNEY B. PAINE. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

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