Title: Frequecy feedback on current loop of current-to-pressure converter
Application Number: 87106633 Application Date: 1987.09.30
Publication Number: 1019429 Publication Date: 1988.07.06
Approval Pub. Date: 2000.08.16 Granted Pub. Date: 2000.08.16
International Classifi-cation: F15B5/00;G05D16/00
Applicant(s) Name: Rosemount Inc. Address:
Inventor(s) Name: Gregory C Brown
Attorney & Agent: DU RIXIN
Abstract:
    A current-to-pressure (I/P) converter provides an output pressure as a function of the magnitude of a variable input DC current. The I/P converter includes a pressure sensor which produces a feedback signal representative of the output pressure. Based upon the feedback signal and the magnitude of the input DC current, an electrical control signal is produced which controls a device for varying the output pressure. The I/P converter also includes a circuit for generating a time-varying signal which is sent back over the current loop wires through which the input DC current flows. The time-varying signal provides an indication of whether the I/P converter is functioning properly. This permits diagnosis of possible causes of control system malfunctions without having to inspect the I/P converter itself.
Time: 8