Patent GB-124359-A (GB)
Title: Electrical Testing Devices.
Inventor: BIERBOWER RICHARD CAREY
IPC: G01R31/00
Filed: 1918-07-15
Abstract: 124,359. Bierbower, R. C. July 15, 1918. Combinations of instruments; capacities, measuring; detecting and locating faults; continuity tests; sparks, testing by. - A portable testing-set for investigating the condition as to continuity, insulation, capacity, &c. of various parts of dynamos, motors, ignition and lighting sets, &c., mostly by spark tests, comprises an induction coil Y, Fig. 1, with interrupter B, condenser 31, and adjustable choking-coil CC, adjustable spark gaps W, X in the secondary circuit, and a rotary selective switch D for making the various connexions required for the different tests. The primary circuit also includes a battery A and switch C, and the condenser 31 and choking-coil CC are connected through switches F<1>, F<2>. A second condenser C<2> is connected between the interrupter B and a fixed terminal S, and various points in the primary circuit are connected to fixed terminals T, U, several contacts of the switch D, lamp-holders 46, 47, resistance 50, and key 51. The spark-gaps W, X are adjustable by means of levers J, K, and a short gap L can be substituted by throwing the lever K on to a lever 6. The secondary circuit is connected to the primary circuit at 3, to several contacts of the switch D, and by flexible leads to terminal clevices Z, 4. Other terminal devices 29, 30 with fiexible leads, and a combined ammeter and voltmeter H, are connected to the contacts of the rotary switch. As shown in Fig. 4, the stem 18 of the switch D carries an insulating-arm 17 and a pointer 22 moving over a dial; springs 15, 16 on the arm bear upon the concave heads of studs a, b, &c. and are connected to springs 23, 24 sliding over semicircular contact-pieces. The dial-plate 56 is connected to the primary circuit to serve as a contact in certain tests. The apparatus can be used for the following tests. Condensers, such as those associated with magneto armatures, are tested by connecting them Letween the terminals 29, 30, placing switch D in position b, opening switch F', and closing switch F<2>. Defective capacity reduces the intensity of sparks at gaps W, X, while short-circuits stop the vibrations of the interrupter B. A rough measure of capacity is obtained by opening switch F<2>, so as to insert the choking-coil CC in the condenser circuit and determining the position of the sliding core for best sparking. High-tension insulation, as between parts of distributors, brush-holders, &c., is tested by attaching one of the terminals 29, 30 to one part, placing switch D in position a, and touching other parts with the terminal 4, defects being indicated by reducing of sparking at gap W. For thin insulation the short gap L is used. Low-tension insulation, as of armature windings, is tested by attaching terminal 29 to the shaft or core, placing switch D in position e, and touching the commutator segments with terminal 30; defects are indicated by the stoppage of the interrupter. The windings of generator and motor armatures are tested by connecting the armature between terminals 29, 30 and placing switch D in position d with switch C open, faults being indicated by the interrupter. Or the armature may be connected between terminals U, V or S, T without regard to the position of switch D, and a telephone connected between adjacent commutator segments, the condition of the winding being indicated by the sound. Armatures of high resistance may be conncted between terminals T, U with the switch C closed. Sparking-plugs are tested by bringing their terminals into contact with the dial 56 and screw L, and moving lever K to widen W until the sparks are diverted by the plug. Continuity of armature windings, fuses, &c. is tested by connecting between terminals 29, 30 and placing switch D in position d with switch C open, so that the primary circuit is energized if the winding. &c. is unbroken; for low-resistance windings, such as field coils, trembler coils, magneto primaries, &c., switch D is placed in position h, and lever 51<1> is rocked, causing sparks if circuit is complete. For high-resistance windings, switch D is moved to position c, so as to connect the armature in parallel with primary coil Y; placing terminal clip Z on the slip-ring should produce sparks at J. Interrupters are tested by connecting them between terminals 29, 30 and placing switch D in position i so as to connect the interrupter across condenser 31. Horns and other devices are connected directly to the battery between terminals 29, 30, with switch D in position e for testing their condition. Lamps placed in sockets 46, 47 are connected to the battery, either directly or through resistance 50, by means of key 51. Dry cells are connected between terminals 29, 30 and coupled to the ammeter or volt-meter by placing switch D in position f or g respectively.