US603778A - And samuel everett - Google Patents

Description

(No Model.)

J. P. STONE & S. E. DOANE.

STARTING DEVICE.

No. 603,778. Patented May 10,1898.

Hill.

LLLLLLL Fs E \A/ITHESEESI UNITED STATES PATENT OFFICE.

JOSEPH P. STONE, OF SCHENECTADY, NEIV YORK, AND SAMUEL EVERETT DOANE, OF MARLBOROUGH, MASSACHUSETTS, ASSIGNORS TO THE GEN- ERAL ELECTRIC COMPANY, OF NEW YORK.

STARTiNG DEVICE.

SPECIFICATION forming part of Letters Patent No. 603,778, dated May 10, 1898.

Application fil d October 22, 1897- Serial No. 656,080. (No model.)

To all whom it may concern: To carry outthe purposes of thisinvention,

Be it known that we, JOSEPH P. STONE, rewe employ a resistance, as in the device at siding at Schenectady,in the county of Schenready mentioned; but instead of an ordinary ectady,State of New YO1lC,2LI1ClSAMUEL EVER- inductance we employ a transformer or com- 5 ETT DOANE, residing at Marlborough, in the pensator or auto-transformer, and we so procounty of Middlesex, State of Massachusetts, portion the windings and the connections of citizens of the United States, have inventthe motorthatthe voltages may be in any proed certain new and useful Improvements in portion desired.

Starting Devices, (Case No. 582,) of which Our invention is illustrated in the accom- IO the following is a specification. panying drawings, in which Ourinventionrelates to apparatus for start- Figure 1 is a diagram of the connections; ing single-phase alternating-current motors, Fig. 2, a diagram of the electromotive forces, and has for its object to provide a device and Fig. 3 a modified form showing that the which shall be more efficient than those in devices may be made adjustable.

r5 common'use. In Fig. 1, A is the alternatorsupplying the Various forms of starters have been desinglephase mains ab, from which leads ab vised which depend upon supplying the mogo directly to the motor-terminals. Between tor with electroinotive force of phase disthese two leads the resistance D and the inplaced from that across the main lines, these ductance, in the form of a compensator C, are

20 devices being used to bring the motor up to connected in series, suitable switches s s bespeed and being in general cut out when ing provided to disconnect the starting detheir object has been attained. One of the vices from the circuit. A lead 0 passes from forms of this apparatus with which we are the third terminal of the motor to one end of familiar consists of a resistance and aninthe compensator, the other end of which is 25 ductance in series across the lines of the connected to the lead Z), while the connection main circuit, connection being taken from a from the resistance D is to an intermediate point between the resistance and inductance point of the compensator-coil. In Fig. 3 the to a third terminal of the motor. This desame arrangement of devices is shown, exvice gives an unsymmetrical three-phase recept that in this instance the resistance D is 30 lation. With it the switch leading to the made adjustable, the switchsbeing provided starting device should be opened before the with a number of contacts leading to differmotor has acquired full speed to avoid the ent points in the resistance, and a similar adpossibility of voltage induced in the motor justing-switch sis adjusted to different points rising above that supplied to it by the phasein the compensator coil. By changing the 3 5 displacing devices, and thus tending to feed proportions of the resistance andinductance 8 5 current back into them. Our invention obthe exact displacement of phase may be efviates the necessity for thus opening the fected to suit the required conditions. switch. By it we provide a voltage at the In Fig. 2 we show a diagram illustrative of third terminal of the motor, which may be our present understanding of the electrome- 0 anything desired, either a symmetrical threetive forces in our invention. In the triangle 0 phase relation or one which shall between a Z) 0, C61) represents the electromotive force the third terminal and either main rise above across the mains, which for the purpose of the voltage across the lines. The effect of illustration may be taken as a hundred Volts. coupling in the motor is to bring down the With the former deviceswhich wehavenamed 45 voltage at the third terminal. By our device in our statement of invention the potential 5 we may so proportion the voltage supplied to at c, as shown by the dotted lines, only difthe motor that when it is connected and starts fers from that of each main by about seventy up the displaced electromotive force will be volts. By our invention, however, the poreduced, so that a symmetrical three-phase tential being stepped up by the compensator 5o relation is established. or transformer 0, this displaced. voltage is raised to a degree illustrated by the point 0, being the usual equilateral arrangement illustrating three-phase electromotive forces. This is, however, the condition which is preferred after the motor has started. To obtain it, the compensator is so wound as to raise the voltage a little more than would normally be desired, or to the point 0 which gives an unsymmetrical three-phase relation where the split-phase electromotive force is higher upon one side of the circuit than the other, so that the difference between it and the outside mains would be, for example, one hundred and twenty volts on one side and approximately one hundred volts on the other. When the added inductance of the motor is brought into circuit, the relation of phase is as shown in the black-line triangle a b c. The compcnsator is for several reasons the preferred form of the device, but an ordinary transform er might be used without departing from our invention, and such a variation or other ordinary engineering variations we aim to include in our claims. The inductive connection to the mains is also within our invention. A diagrammatic indication of such a connection is shown in Fig. 3, the transformer T having its primary in the generator-circuit, and the motor being connected to the secondary.

In Fig. 1 we show in dotted lines that the phase-displacing devices may be themselves included in the circuit of a step-up transformer T, the effect of which would be to raise the potential difference between the middle terminal of the motor and the mains, so that the point e of the triangle in Fig. 2, representing the split-phase electromotive force,

would be, for instance, at thus giving a greater starting torque.

lVhat we claim as new, and desire to secure by Letters Patent of the United States, is

1. A starting device for a single-phase alternating-current motor, comprising two phasedisplacing devices in series across the mains, and in shunt to the motor, one of the phasedisplacing devices consisting of a step-up transforming device designed to deliver from a point between the phase-displacing devices to a third terminal of the motor a higher than normal voltage.

2. In combination, a motor having three terminals, two of which are connected to a source of singlephase current directly or inductively, and the third terminal of which is connected to the mains through phase-displacing devices consisting of a resistance and step-up transformer in series across the mains, the third terminal of the motor being connected between the phase-displacin g devices.

3. As a means of starting a single-phase alternating-current motor, a resistance and a compensator in series across the main circuit, the resistance being connected at one end to one side of the main circuit and at the other end to an intermediate point of the compensator, the latter being connected at one end to the other side of the circuit and at the other end to the third terminal of the motor.

In witness whereof we have hereunto set our hands this 10th day of October, 1897.

JOSEPH P. STONE. SAMUEL EVERETT DOANE. Witnesses:

B. 1;. HULL, HARRY Bo'rTonLEY.

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