US1447026A - Automatic liquid starter for alternating and three-phase current motors - Google Patents

Description

Feb. 27, 1923. 1,447,026

Y J. LEWIN AUTOMATIC LIQUID STARTER FOR ALTERNATING AND THREE P ASE QURR T QTQRS Filed June 5, 1.922

Patented Feb. 27, 1923.

UNITED STATES PATENT OFFICE.

JOHN LEWIN, 0 F BEBLIN-HALENSEE, GERMANY.

CURRENT MOTORS. v

Application filed June 5, 1922. Serial No. 565,950.

To all 407mm it may concern: I

Be it known that I, JOHN Lawn, a citizen of the Republic of Germany, residing at Berlin-Halensee, Germany, have invented certain new'and useful Improvements in Automatic Liquid Starters for Alternating and Three-Phase Current Motors; and I do hereby declare the following to be a full, clear, and exact description of the invention. I

For starting alternating and three-phase current motors it has been suggested to effeet a diminishing of the resistances within the armature winding, automatically, by forming the said resistances by a conducting liquid, which latter under the influence of centrifugal force is distributed within a casing attached to the shaft of the motor in such a. manner, that the effective crosssection of the liquid is increased, while the resistances are gradually diminished. The insulated electrodes electrically connected with the windings of the armatures are of annular shape but rigidly secured within the casing.

In contradistinction to this arrangement, the electrodes of the present centrifugal liquid starter are constructed as swinging segments of a concentric ring in such a manner, that not only the effective crosssection of the liquid layer is increased on account of the action of the centrifugal force, but also the distance of the electrodes from the walls of the casing will be diniinished gradually. The liquid resistances connected to the armature windings are thus effectively diminished toa far greaterextent than is possible with the annular fixed electrodes.

The swinging electrodes are advantageously made of flexible material so that they will be capable of better clinging to the walls of the casing during rotation. Besides, the electrodes may be provided at certain points of their surfaces facing the walls of the said casing, with insulating material, so that in this instance a contact of the electrodes with the metal walls of the casing is avoided.

Inthe drawings Fig. 1 is a starter in cross-section of a starter at rest, perpendicularly to the axis of rotation of the casing.

Fig. 2 is a cross-section thereof parallel to the axis of rotation of the casing.

Figs. 3 and 4 show the starter during rotation.

Fig. 5 shows the final trodes.

Figs. 6 and 7 illustrate the connection of the starter with the armature winding.

On the shaft WV of the motor.(Fig. 2) is secured the casing A, containing the electrodes B and B pivoted on pins S and S respectively. The pins S and S and likewise the electrodes B and B electrically connected with said pins, are insulated from the casing A and connected with the armature windings E and E (Fig. 6), while the casing A is connected to the common point of connection of the armature Winding by means of the shaft W. This arrangeposition of the elecment will be suitable for a rotor wound for two phases.

The electrodes are caused by springs F and F to engage insulated stop pins P and P respectively, so that the former will only be able to swing outwardly under the action of centrifugal force when the speed of rotation increases (Figs. 3 and 4). Part of the casing A is filled with a conducting liquid suchas for instance, soda-water, which will remain at the bottom part thereof while the device is at rest. lvlien the motor is started the effective cross-section of the liquid formed at first by the liquid X is too small for the armature current, but as soon as the casing X carried along so that the immersed surface of the electrodes B and B gradually increases. that is the resistance diminishes. until. the liquid according to Figs. 3 and 4 is caused to form an annular layer. into which the electrodes B and B are totally immersed. The quantity of the liquid must be adapted in accordance with the respective distance. of the electrodes from the inner walls of the said casing. At a further increase of the speed of rotation the electrodes B and B will swing outwardly and approach the wall of the casing. thus further diminishing the resistance. It the motor ultimately has reached its proper number of revolutions, the electrodes will come near the wall of the casing A (Fig. 5) to an extentequal to the thickness of the insulating members J and J attached to the electrodes. whereby the tension of the springs F and F is overcome. The thickness of the layer of liquid between the elec- A is rotated. the liquid Hit) ti'odes l3 and B andthe walls of the casing A so snlallthat practically through said layer of liquid a short-eireuiting of the rotor-windings is efl'eeted, without running the danger of: the electrodes burning fast on the Walls of the easing.

Fig. 2' shows diagrainniatieally the armature starter of a rotor WOIIIKl for threephases.

I claim 1,. An automatic liquid starter for alternating and three-phase current motors eon yn'ising a casing mtatahle with the shaft of the motor and "partially filled with a condueting liquidforming resistances included in the winding of the armature, and segi'nental electrodes in the casing arranged to swing outwardl under the action of (en- -Vlt ILQSSQSI E. HI. Cinema,

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