Protective mechanism in electrically operated devices

摘要

PCT No. PCT/EP83/00062 Sec. 371 Date Nov. 7, 1983 Sec. 102(e) Date Nov. 7, 1983 PCT Filed Mar. 4, 1983 PCT Pub. No. WO83/03160 PCT Pub. Date Sep. 15, 1983.To protect the operator of an electrically powered apparatus in a damp room or in the presence of water or other electrically conductive fluid against an electric shock, there is provided a protective device comprised of a probe in the form of a double conductor which the user cannot contact when handling or operating the apparatus. In the presence of a conductive fluid the impedance of the probe changes. The probe is connected to the input of a trigger switch circuit which includes a semiconductor switch. The trigger circuit triggers the semiconductor switch when the impedance of the probe changes. The current which flows as a result of the closing of the semiconductor switch releases an automatically opening switch, the contacts of which lie in the incoming power supply wires of the apparatus, which contacts are normally held closed by means of a material which is fusible upon direct or indirect heating by means of said current.