GB427409A - Improvements in and relating to "tell-tale" devices for indicating the failure of anelectric circuit - Google Patents

Abstract

427,409. Electromagnetic interrupters. DONALDSON, F. G., 14, The Parsonage, Manchester. Oct. 20, 1933, No. 29046. [Class 38 (v)] [See also Group XXXVIII] For giving an intermittent alarm when failure takes place in a circuit, the core of a solenoid is arranged when de-energized to close contacts in its own circuit, and that of the alarm and to open the circuit when energized, the core contacting with and so operating the member controlling the contacts after a certain amount of lost motion. The circuit of the apparatus is shown in Fig. 2 in which the coil a and controlled circuit m are normally connected in series energizing the coil to hold open the contacts j. When the circuit m fails the core a is de-energized closing at j the circuit to alarm l and its own circuit so that the alarm is operated intermittently. As shown in Fig. 1, the core d is pressed by spring e away from the coil a. When the coil is energized, the core moves to the position shown, the plate g after a certain amount of movement contacting with the switch member i to force the member to move with the core and open the circuit between spring blades and conducting ring k. When the coil is de-energized, the core is moved away from the coil by spring e and before reaching the end of its travel the plate g engages the shoulder on member h to move the member to allow springs to be reconnected by conducting ring k. The clearances in the unit are made small and the unit is made airtight to allow the displaced air to slow down the movement and if the current through j is heavy or of high voltage, the whole core may be immersed in oil to give an oil break on the spring contacts.