Relay driving circuit for a latch-in relay

US5079667A · kind A · utility

Assignee

• Matsushita Electric Works, Ltd. · JP

Inventors

• Fumihiro Kasano · Sakai, JP
• Hans Sauer · Bamberg, DE
• Heinz Ritter · Schongau, DE
• Wolf Steinbichler · Bad Feilnbach, DE
• Sepp Antonitsch · Otterfing, DE

Key dates

• Filing date: Nov 30, 1989
• Grant date: Jan 7, 1992
• Expiry date: Nov 30, 2009

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01H47/226
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A relay driving circuit for a latch-in type magnetic relay having an excitation coil, generating a set current and a reset current of opposite polarity for the coil. A capacitor is provided between the input terminals of the circuit in series with the coil. A set switch is connected in series with the coil and the capacitor, and a reset switch is connected across the series combination. An input voltage level detector is provided to make the set switch conductive, thereby applying the input voltage to the excitation coil and the capacitor to provide the set current. As the input voltage decreases below the trigger level, the detector makes the reset switch conductive to allow the capacitor to discharge current in the opposite direction through the excitation coil. The circuit includes a disable switch responsive to the capacitor being charged to a voltage level sufficient to provide the reset current, the disable switch setting the set switch to a non-conductive state to thereby prevent the capacitor voltage from being reversely applied.