US2450577A - Electrical coil tester - Google Patents

Description

Oct. 5, 1948. A. 6. BROWN ELECTRICAL con. TESTER Filed March 22,. 1 944 uvmvron BY ANTHONY G1 B/aow/v I ATTORNEY Patented Oct. 5, 1948 Anthony .G. B own, I du trie n -Q of Delaware Application March 22 1 4, Serial :No.

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O o, .ass en r, y Precision Ohio, a corporation :1 c nc- 1- us -15a This invention relates to an electric coil tester and has as its object to provide a coil tester oi circuited turn or turns in coils to be tested.

A preferred embodiment of the invention is illustrated in the accompanying drawing in which the single figure is a view in side elevation, with certain parts broken away, of a coil tester constructed according to the principles of the invention. n I

The operating parts of the mechanism are carried by an insulating base I in a housing 2 having a platform or shelf -3 adapted to support a coil 4 to be tested. Supported by the base I between 2. pair of angle irons 5 is a stack of, E- shaped laminations 6, the completed stack having a central exciting leg *1, end legs 8 and 9, and short and long arms magnetic circuits are able laminated arm or armature I2 magnetically linking the upper ends of the three legs 1, 3 and 9. The armature I2 is loosely mounted on a loose pivot I3 on a pair of standards l4 and is biased to the open position shown in full lines by a r n A ai o s anda ds I 5 n sh p otal support for a shaft I1 carrying a can; I8 and an operatin handle I9. All of the aforementioned structure is contained within the housing 2 with the exception of the handle I9 which extends outside of the housing on its shaft I1 for manipulation in order to cam the armature I2 downwardly firmly against the legs of the magnetic circuit in its broken line position.

The upper ends of the laminated legs 1, 8 and 9 may be riveted as indicated by the numeral 20, and the lower extremities of the arm portions Ill and II may be clamped by bolts 2| which also serve to mount the laminated structure between the angle irons 5, the bolts 2| being located outside of the active magnetic circuits. The laminations of the armature I2 may be riveted, bolted or soldered together, the latter being at present preferred, with the solder applied only to the end portions outside of the active magnetic circuits.

In practice, the central leg 1 is ground ofi to a level very slightly below the tops of end legs 8 and 9, and the pivot I3 has sufficient looseness so that the action of the cam ill will insure a firm contact between the armature I2 and the ends of the legs 8 and 9. A slight gap between the armature I 2 and the central leg 1 is not objectionable. The central leg 1 carries preferably Ill and I I respectively. The completfid through a movan exciting coil 25 adapted to establish one magnetic circuit throughthe short 8, and a portion of the armature 1-2, and a sece ond magnetic circuit through the long arm II,

t e les 9, a d a oth portion with a neon lamp 3 I "T9 compensate for the unequal flux distribution resulting from the unequal lengths of the arms I l) and I I in the preferred embodiment, the balance coil 26 is Wound with 575 well below the ignition voltage If the test coil 4 con, ta ns no short circuited turns, the magnetic cirui is n t affected by the of the coil The values prov de a compact device, this tester ondary of a transformer. This additional flow of current in the exciting coil sends more flux through the balance coil 26, thus increasing its induced voltage. The voltage in coil 21 remains arm I 0, the "legapproximately the same, the increased difierence in voltage between the two coils being of a sufficient magnitude to ignite the neon bulb.

In the illustrated embodiment the magnetic circuit i purposely unbalanced in the manner described to increase the window area in the coil testing side. This unbalance is partially compensated for by the difference in turns in the balance coils, but the unbalance must not be allowed to become excessive if a high degree of sensitivity is desired. It is therefore desirable to remove only sufficient turns from the coil 26 to bring the voltage differential between coil 26 and 21 safely below the ignition voltage of the bulb.

The amount of voltage unbalance produced in the indicating circuit for a single short circuited turn depends upon the current flowing in the short circuit path, whereby it is apparent that coils of relatively fine wire may be tested, as well as coils of wire larger than the No. 15 wire referred to. In testing different coils in this manner it is not necessary to make any changes or adjustments inasmuch as the neon lamp will function satisfactorily on any voltage within a wide range above its ignition voltage. Likewise, the unexpected presence of a number of short circuited turns in a test coil will cause no injury to the apparatus.

This feature offers a distinct advantage over coil testers employing delicate meters subject to injury if overloaded. The present coil tester is thus seen to be electrically a well as mechanically rugged, and well adapted to use by unskilled operators, while at .the same time being always operative at its maximum sensitivity.

An advantage contributing to the rapid and efficient testing of coils by unskilled operators is that the only indication to be interpreted is the observation as to whether the lamp 3| lights or does not light to clamp the armature 12 in its lower position. The device is designed for production use to facilitate the rapid testing of a large number of coils with a minimum of manual effort and manipulation.

Various changes in the construction and. arrangement may be made, and all such modifications are included in the invention, the same bewhen the handle t9 i rotated ing limited only by the scope of the appended claim.

I claim:

A coil tester comprising a laminated iron core having a central exciting leg and a pair of end legs forming a divided magnetic circuit, a stationary upright and a laminated armature pivoted thereto adjacent one of said end legs, spring means biasing said armature out of engagement with all of said legs manually operable cam means bearing upon said armature between said end legs for moving said armature into engagement with all of said legs to establish iron paths for said magnetic circuits, an exciting coil on said central leg for producing an alternating flux in said magnetic circuits, a pair of balance coils on said end legs connected in opposition, the cores of the coils being substantially in the form of a capital E whereby said armature is adapted to engage the cores oi" all three legs to close the magnetic circuit and a neon lamp connected in series with the coils which are connected in op-' position with said balance coils, said balance coils being unbalanced only to such an extent that the difference in the voltages thereof is less than the ignition voltage of said lamp so that upon energization of said exciting coil ignition of said lamp is prevented in the absence of a short circuited turn in a coil to be tested and cause the ignition of said lamp when said test coil contains at least one short circuited turn.

ANTHONY G. BROWN.

file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Isaacson, Radio News for May 1931, pp. 1025 and 1027.

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