Low current binary input subsystem
AssigneeABB Power T&D Company Inc.
InventorsRaymond E. Johnson, deceased, B. S. Johns, administrator, Janusz W. Dzieduszko
Life of this patent
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Abstract
Disclosed is a low current binary input subsystem for providing a binary input signal to a data acquisition system. The binary input subsystem monitors the open/close state of a field contact and provides galvanic isolation of noisy field contacts, high noise immunity, a steady state current of approximately 1.2 milliamps resulting in power dissipation of approximately 0.25 watts for a 125 VDC input, and a momentary high current pulse of approximately 150 milliamps for a duration of approximately 4 milliseconds during field contact closure to aid in cleaning of oxides from the field contact.
Claims9
A binary input subsystem for providing a binary input signal to a data acquisition system, comprising
- (a) a pair of terminals (T1, T2) for receiving an electrical signal indicative of the open/close state of contact (FC);
- (b) threshold means (20) operatively coupled to said terminals for receiving an applied voltage and ensuring that the binary input will remain in an "off" state until said applied voltage exceeds a prescribed threshold, said "off" state indicating that said contact is open;
- (c) isolation means (22) operatively coupled to said threshold means for providing a galvanically isolated binary input signal ("IN") to the data acquisition system;
- (d) constant current means (24) operatively coupled to said isolation means for ensuring that a prescribed operating current is applied to said isolation means;
- and
- (e) current pulse means (26) operatively coupled to said isolation means for providing a current pulse through said contact when said contact closes, said current pulse being of a designed duration and amplitude sufficient to clean a dielectric film from said contact.
A binary input subsystem for providing a binary input signal to a data acquisition system, said binary input signal being indicative of the open/close state of field contact (FC), comprising:
- (a) a pair of terminals (T1, T2) coupled to a series combination of a battery (B1) in series with said field contact (FC);
- (b) circuitry for providing a galvanically isolated binary input signal ("IN") to a data acquisition system while requiring low current during steady state operation and providing a momentary high current pulse to said field contact upon closure of said contact, said circuitry comprising an optocoupler receiving a signal indicative of the open/close state of said field contact and providing a galvanically isolated binary input signal;
- (c) a constant current source operatively coupled to said optocoupler for ensuring that said optocoupler consumes a predetermined maximum amount of power;
- and
- (d) a high current pulse circuit operatively coupled to said constant current source and to said field contact, said high current pulse circuit providing a momentary high current pulse through the field contact when the contact closes, wherein the duration of the pulse and the amplitude of the pulse are predetermined.
Dependencies are inferred from the claim text.