Protective mechanism in electrically operated devices

US4589047A · kind A · utility

Inventors

• Harry Gaus · Kronberg, DE
• Hagen Gross · Bad Homburg vor der Höhe, DE

Key dates

• Filing date: Nov 7, 1983
• Grant date: May 13, 1986
• Expiry date: Nov 7, 2003

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02H5/083
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

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.