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:
Dec. 13, 1983
Filed:
Sep. 22, 1982
Rafael Hernandez, Jimenez, MX;
Edmund E Chow, Lilburn, GA (US);
Marion L Moncrief, Jr, Stone Mountain, GA (US);
Frank S Glass, Stone Mountain, GA (US);
Process Technologies, Inc., Tucker, GA (US);
Abstract
Apparatus for operating a motor driven device and testing the state of a limit switch in series with the motor, in the environment of a field interface device in a tank farm is disclosed. During operation of a relatively high power relay (115), a latched (145) signal ties one side (130) of the two-wire circuit to ground through a low impedance (139). When testing of the state of a series limit switch (119) is needed, the same supply voltage is switched onto one side of the two-wire circuit (147) but the low side of the two-wire circuit is grounded through a relatively high impedance (135, 136) to prevent sufficient current for operating the relay coil (117) from flowing. The presence or absence of current through the high impedance is detected through a coupling device (137) which provides a logical one or zero on an output line (68) to determine whether the limit switch is open or closed.