The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 22, 1995
Filed:
May. 14, 1993
Mark E Innes, Asheville, NC (US);
Rick A Hurley, Fletcher, NC (US);
Eaton Corporation, Cleveland, OH (US);
Abstract
A controller such as a programmable logic controller (PLC) is coupled to a load such as a contactor or motor starter through an interface that operates over a range of DC or AC voltage and couples a Start output of the controller to the load through a low current switch such as an opto-relay. The interface has a charging circuit coupled to the controller output, with a switching transistor, a load resistor and a capacitor in series. The low current switch is operated from accumulated charge in the capacitor and couples power to the load device. Charging of the capacitor to a threshold switches off of the transistor for an interval timed by a one-shot, during which the low current switch remains activated due to current draining from the capacitor. In an AC embodiment with a triac controller output, the capacitor continues to power the low current switch for the remainder of the positive AC half cycle, regardless of the triac, which may cease conduction due to lack of sufficient loading. The circuit substantially reduces the current dissipation of an interface between a PLC and a motor starter or contactor. The interface can include optically isolated signalling in both directions, including feed back of contact status and trip indications to inputs of the PLC.