Improvements in, or relating to, combined 'on' or 'off' indicator and overload protective systems for electric switchgear

摘要

439,655. Protective cut-out arrangements. SADLER, A., 65, Temple Row, Birmingham.-(Schiele & Bruchsaler Industriewerke Akt.-Ges. ; Baden-Baden, Germany) Sept. 12, 1934, No. 26121. [Class 38 (v)] In an overload protective system for an electromagnetically operated switch b, control contacts operated by the protective device are adapted to control both the operating coil d of the switch and an auxiliary circuit containing an indicator, such as a discharge lamp m. In the arrangement shown, the control contacts i, k are normally held closed, against the action of a spring h, by a latch f. The overload device comprises three bimetallic strips c included in the phase wires R, S, T, the strips being connected to a pin or rod e adapted to release the latch f in the event of an overload in any of the phase wires. When the control contacts are closed the indicator lamp m is short-circuited, and the switch b can be closed by closing a switch n, which may be located at any desired distance from the switch b. On overload, the contacts i, k separate and the lamp m is thrown into circuit with the coil d, the current being reduced to a value which is insufficient to hold the switch b closed but sufficient to light the lamp. The control contacts are reset by a push-button l.