US1723322A - Electrical relay-control apparatus - Google Patents

Description

1929- F. ANDORFF ET AL 7 1,723,322 I ELECTRICAL RELAY CONTROL APPARATUS Filed March 8, 1926 I v fix/6735m- 2717 dzzabrflf m? Zarzcbmamz Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

FRITZ ANDORFF, OF VIERNHEIM, AND KURT LANDSMANN, OF MANNHEIM, GER- MANY, ASSIGNORS TO AKTIENGESELLSCHAFT BROWN BOVERI & CIE., OF BADEN, SWITZERLAND, A JOINT-STOCK COMPANY OF SWITZERLAND.

ELECTRICAL RELAY-CONTROL APPARATUS.

Application filed March 8, 1926, Serial No. 93,025, and in Germany March 16, 1925.

This invention relates to electrical relay apparatus, particularly to the type designed to be operated by overloads in the controlled circuit.

The general object of the invention is the provision of apparatus whereby the tripping time of the relay may be varied without necessitating a corresponding variation in the minimum tripping current.

Another object is the provision of such apparatus in a construction which may be built in small space, which is certain in operation, and which is adapted to handle heavy overload currents without danger.

Other and further objects of the invention will be pointed out or indicated hereinafter, or obvious to one skilled in the art upon an understanding of the invention.

In the drawing forming a part of this specification we show in diagrammatic fashion a structural arrangement in which the invention may be embodied, but it is to be understood that this is presented for illustration only and is not to be given any interpretation having the efiect of limiting the invention claimed, short of its true and most comprehensive scope in the art.

The drawing is a diagrammatic illustration of relay apparatus embodying the invention, arranged to operate a circuit breaker.

Current relays designed to operate with a time la usually involve more or less complocated constructions in the nature of clockwork, Ferraris disc apparatus, or the like, which render the apparatus costly and more or less susceptible to functional derangements. The simpler constructions, such as those generally used for protection of motors, etc., of which thermic relays and other delayed action relays are examples, do not admit of desired variation of the tripping time without variation of the tripping current. By the present invention I make possible such variation in the tripping time more or less independently of the tripping current, so that the tripping time may be lengthened to accommodate high overloads for a short period, Without necessitating an increase in the load requisite to trip the relay when such a load is continued for a dangerously extended period. One example of the application of the invention is in the protection of squirrel cage motors which have to accelerate large masses on starting, the action being such as to cause an overload conditi on for a starting period of comparatively short duration.

The nature of the invention will be understood immediately upon an understanding of the illustrative form.

As shown in the drawing, 10 designates the switch or circuit breaker which is operated by the relay 11. The time operation of 15 includes the adjustable portion made up Y of two arms m and 'n. which are rotatably mounted on the axis 0 so that either may be swung into or out of cooperation with the ends of the core member to complete the magnetic circuit of the third limb. The arm in is of greater cross section than the arm a, and consequently when positioned to close the magnetic path through the limb 15, introduces more iron into the core circuit than does arm n. The adjustable arm member may also be moved to a third position, wherein the radius designated I is interposed in the limb 15, thus opening the magnetic path through that limb. As a result of this arrangement, the amount of iron in the core is variable in three quantities, viz, a maximum quantity when the arm 'lIL is in the core circuit, an intermediate quantity when arm n is in the core circuit, and a minimum quantity when the limb 15 is open. In the latter instance, the entire core flux passes by way of the limb 14:. The result of this variability is a selective variation in the saturation requirements of the core, whereby the quantity of secondary current obtainable with a given primary current may be varied and the rate of increase in the secondary current relative to a given increase in the rate of the primary current is likewise varied. The action results from the fact that when the transformer is working at a high saturation an increase in primary current does not give a proportional increase in secondary current, as compared with operation at a low saturation, the reason being that as the saturation is raised, an increase in proportion of the primary ampere circuit of the core, a secondary current will not increase with a given increase of primary turns are required to magnetize the iron. As a consequence of the arr ngement illustrated, thcreiore, when the arm m 1s in the magnetic current so rapidly as when the lesser arm n is in the core circuit. Accordingly, the time required for operation of the relay 11 after the startof the overload in the controlled circuit may be varied selectively, the relay being operated on the same overload in any instance. I a

, The eii ect may also be obtained by other arrangements for varying the leakage reactance of the transformer and in a fashion varying the saturation. It is a comparatively simple matter to provide an arrangement in which the conditions are such that with any of the relative arrangements, there is no appreciable proportionaldecrease of secondary current after some selected limit of primary current is reached. For this purpose it is desirable that, in adjustment, the whole iron path be not entirely interrupted, for example as shown in the drawing, wherein it is bridging pos tion.

possible to always maintain a closed iron circuit, the active iron cross section, however, being varied.

What we claim is:

1. Intransformer apparatus, a. core having an air gap, operating winding means disposedon said core, and a member having ditterent reluctance values between different pairs of oppositely-disposed points on its outer surface and being supported for movement in such wise as to place any one of such pairs of points in said gap to the exclusion of the remainder of such pairs of points.

2. In transformer apparatus, a core having an air gap, operating winding means disposed on said core, and a member-comprising arms having different reluctance values and each being operable to substantially bridge said gap, said member being supported for movement in such wise as to provide for movement ofsaid arms selectively into FRITZ ANDORFF. KURT LANDSMANN.

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