GB569021A - Improvements in electric indicating devices applicable to gate end boxes and the like for use in mines - Google Patents

Abstract

569,021. Protective cut-out arrangements ; indicators for switches. VICTOR PRODUCTS (WALLSEND), Ltd., [formerly CROFTON & CO. (ENGINEERS), Ltd., C.], and MANN, R. W. July 24, 1943, No. 12076. [Class 38 (v)] In a leakage-indicating arrangement for gate end boxes in mines, a lamp is arranged to emit a beam under all working conditions and to go out on leakage occurring or the main isolator being opened, and is associated with a press button employed for resetting overload contactors and the leakage relay. The lamp d is placed behind a red glass rod c let into the push button a in the front x of the gate-end box, and is placed in series with normally closed contacts of the leakage relay n across a transformer, the primary of which is energized by the main circuit controlled by an isolator y, Fig. 4 (not shown). The lamp thus indicates the condition of the isolator and transformer fuses, in addition to showing that the leakage relay has operated, the latter operation causing a lever o to assume the dotted position shown in Fig. 2. Each of these contactors 4 ... 6 has a push button m which assumes the position m<1>, Fig. 2, when the contactor trips on overload. In order to reset the push buttons m, an insulating bar k, guided on pins l, is adapted to be pushed backwards against spring-action by means of an arm f on the inner end of push button a when the latter is depressed. A further arm g on the end of button a carries a projection q, Fig. 2, adapted to engage and reset the lever o, for which purpose the button a is depressed and then rotated anti-clockwise, Fig. 1, by means of a special key fitting over, and engaging a notch p in, the button. A third arm h on the button normally works in a slot t between two projections r, s on the front x and is urged by spring u against projection r. When the button a is rotated after depression, the arm h being clear of the gap t moves along the back of projection s against the enlarged end s<1> thereof. When released, the button is first rotated by spring u and then restored by spring b. The leakage relay coil is in a circuit connecting the neutral wire of the 3-phase supply to earth, so as to be energized only when unbalance current flows in the neutral.