US1539429A - Overload-circuit breaker for motors started by means of a starting resistance - Google Patents

Description

May 26, 1925. 1,539,429

w. SARTIG OVERLOAD CIRCUIT BREAKER FOR MOTORS STARTED BY MEANS OF A STARTING RESISTANCE Filed March 10, 1922 til Patented May 26, 1925.

UNITED STATES PATENT OFFICE.

WILLY SARTIG, OF ESSEN, GERMANY, ASSIGNOR 'IO FRIED. KRUIP AKTIENGESELL- SGHAFT, 0F ESSEN-ON-THE-RUHR, GER-MANY.

OVERLOAD-CIRCUIT BREAKER FOR MOTORS STAR-TED BY MEANS OF A STARTING RESISTANCE.

Application filed March 10, 192-2.

To all ill/1077b it may concern:

Be it known that I, VILLY San'ric, residing at Essen, Germany, a citizen of the German Republic, have invented a certain new and useful Improvement in Overloadlircuit Breakers for Motors Started by Means of a Starting Resistance, of which the following is a specification.

This invention relates to improvements in overload circuit-breakers which are designed to protect electric motors from overload and the sensibility of which varies automatically during the starting of the motor to be protected, such as disclosed for example in the application for Letters-Patent of the United States filed December 29, 1921, Serial N o. 525,695 in the name of Felix Tobien.

The present invention has for its object to provide an overload circuit-breaker of this character the sensibility of which is increased as. long as a body which is moved on a prescribed track by the electric motor to be protected, is within a definite section of this track.

The invention is especially adapted for use on electrically driven vehicles or cranes which should travel at reduced speed on one or more sections of their track.

lVith the aforesaid end in view the invention consists in the arrangement, construction and combination of parts to be herein described and particularly pointed out in the appended claims.

The drawing shows, by way of example, av diagram according to the invention in which the motor to be protected is designed to drive a travelling crane.

Referring now to the drawing, A designates the current feeding line and B the trolley. Connected in series with the trolley B are: the main current releasing coil C, the break of the overload circuit-breaker which consists of two stationary contact-points C and C and a movable contact member C actuated by the releasing coil C and adapt ed to bridge the two contact-points, the starting resistance D along with its sliding contact 41 and the main current motor E E, the field winding E of which is grounded by one of its ends. A current branch including a magnet coil C and a series resistance C is connected in parallel to the releasing coil C and the break C C The magnet coil 0 acts in the same sense as Serial No. 542,736.

the releasing coil 0 and it works on the same magnetic circuit as the releasing coil C. The exciting force of the magnet coil 0* is determined in such a manner as to be unable to open the overload circuit-breaker when same in closed position, while it is adapted to hold the circuit-breaker, when opened, in its cut-out position contrary to the action of a tension spring C which engages the movable contact member C Connected in. parallel with the main current motor E E is a line K which contains another magnet coil G for the overload circuitbreaker and a series resistance G. The magnet coil C likewise acts on the same magnetic circuit and is wound in the same sense as the magnet coils C and C The circuit K further comprises a contact device consisting of a conductor bar M and a sliding contact M The sliding contact M is attached to the frame N of the crane, whil the conductor bar M is arranged parallelly to the track P of the crane-frame N and is of such length as to cause the sliding contact M and the current bar M to remain in contact along the whole section of the track P on which the crane should travel at reduced speed.

In the position of the several parts, shown on the drawing, in which the sliding contact M is in contact with the conductor bar M, in, which the starting resistance D is partly switched oil and. in which the overload circuitbreakcr is closed, the magnet coils (l and C are energized so that the overload circuit-ln'eaker possesses comparatively high sensibility. The degree of this sensibility conforms to the strength of the excis tat-ion of the magnet coil 0". This excitation as well as the speed at which the crane is driven, depend u pen the size of the switchedin portion Oil: the starting resistance D. a

If the speed of the crane is increased by switching oil further steps ol the starting resistance, the sensibility of the overload circuit-breaker will. likewise be increased for the reason stated above. Now the size of the series resistance G is such as to cause the sensibility of the overload circuitbrealrer to become so high, at a definite speed of the crane which is lower than the speed attainable with entirely cut-out start ing resistance, that the circuit-breaker will enter into action, provided, of course, that the contact device M M is still closed.

As soon as the sliding contact M leaves the conductor bar M in the further course of the travelling motion of the crane, the magnet coil C Will be de-energized and the sensibility oi the overload circuit-breaker vill be accordingly reduced, so that the crane can be driven at a higher speed on the track-sections situated beyond the section limited by the current bar v1.

It will be obvious that it Will be Within the scope of the present invention to provide still other conductor bars to be connected in parallel with the conductor bar M and arranged at other places of the crane-track P, such as for example at the ends of the track. Further, the circuit K which includes the magnet coil can be connected to include the armature E alone instead of the motor E E.

Claims:

1. In combination with an electric motor, a body propelled by said motor, a prescribed track for said body, a main circuit in connection with said motor, an overload circuit breaker having a main current releasing coil in said circuit, an auxiliary coil for supplementing the action of said main current releasing coil, and means for automatically exciting said auxiliary coil at predetermined points in the travel of said body.

2. In combination with an electric motor,

a body propelled by said motor, a prescribed track for said body, a main circuit in con- I nection with said motor, an overload circuit breaker having a. main current releasing coil, a shunt circuitin connection with said main circuit, an auxiliary coil for supple menting the action of said main circuit current releasing coil disposed in said shunt circuit, and means for automatically opening or closing said shunt circuit at pro-dotermined points in the travel of said body.

3. In combination with an electric motor, a body propelled by said motor, a prescribed track for said body, a. main circuit in connection with said motor, an overload circuit breaker having amain current releasing coil, a shunt circuit in connection with said main circuit, an auxiliary coil for supplemcnting the action of said main circuit current re easir coil disposed in said shunt circuit and means for automatically opening or closing; said shunt circuit at predetermined points in the travel of said body, said means comprising a contact device disposed in said shunt circuit. one of the members of said cont-act device being arranged along said track and the other member of said contact device being attached to said body.

The foregoing specification signed at Rssen, Germany, this 26th day of January,

WILLY SARTIG.

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