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EP0326237A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Control circuit with validity-determining arrangement

Assignee: S&C Electric Co
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Filing: 1989-01-05
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Granted: —
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Expires: 2009-01-05
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Abstract

Abstract An arrangement is provided for checking the validity of a sensed-current signal (at 20) from a current-sensing device (24). The sensed-current signal (at 20) represents the current in a line (22). An associated control circuit (15,10) utilizes the sensed-­current signal (at 20) to indicate or predict the presence of undesired overcurrent conditions. When such conditions may be present, the sensed-current signal (at 20) is checked to determine if the sensed-current signal is valid; i.e., whether the sensed-­current signal (at 20) accurately represents the current in the line (22). If the sensed-current signal is invalid, no trip signal (at 25) is generated to interrupt the current (via 30). If the sensed-current signal (at 20) is valid, the control circuit (15,10) generates a trip signal (at 25) to control operation of a circuit-­interrupting device (30). In a particular arrangement, the load on the current-sensing device (24) is changed (via 35,40) to determine if the sensed-current signal is valid. If the sensed-current signal (at 20) is valid, the level of the sensed-current signal remains in a valid range and the control circuit issues the trip signal (at 25). If the sensed-current signal is invalid, the level of the sensed-current signal changes. In response, the control circuit (15,10) does not issue the trip signal (at 25) and is reset to an initialized mode to monitor for a valid overcurrent condition in response to the sensed-current signal. In a specific arrange­ment, the current-sensing device is an iron-core transformer which saturates at high current levels.

Inventors

  • 👤 Joseph W. Ruta

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-08 16:56
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/08; H02H3/093; H02H1/00; H02H1/04; H02H1/046

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 117 words
A control circuit (15,10) for detecting the presence of overcurrent conditions comprising: current-sensing means (24) responsive to the current in a line (22) for providing a sensed-current signal (at 20) that represents the current in the line (22); and means (15) responsive to said sensed-current signal (at 20) for detecting overcurrent conditions and for generating a control signal (at 88), the control circuit being characterized by validity-checking means (10) responsive to said control signal (at 88) for determining whether or not said sensed current signal (at 20) accurately represents the current in the line (22), said validity-checking means (10) comprising means (10 via 35 and 40) for changing the load on said current-sensing means (24 at 20).
Claim 2
Dependent Claim 117 words
A control circuit (15,10) for detecting the presence of overcurrent conditions comprising: current-sensing means (24) responsive to the current in a line (22) for providing a sensed-current signal (at 20) that represents the current in the line (22); and means (15) responsive to said sensed-current signal (at 20) for detecting overcurrent conditions and for generating a control signal (at 88), the control circuit being characterized by validity-checking means (10) responsive to said control signal (at 88) for determining whether or not said sensed current signal (at 20) accurately represents the current in the line (22), said validity-checking means (10) comprising means (10 via 35 and 40) for changing the load on said current-sensing means (24 at 20).
Claim 3
Dependent Claim 48 words
The control circuit of claim 1 further comprising means (e.g., 90, 94, 96 and 101 of 10) responsive to said control signal (at 88) for generating a trip signal (at 25) when said sensed-current signal (at 20) is determined to accurately represent the current in the line (22).
Claim 4
Dependent Claim 50 words
The control circuit of claim 1 wherein said validity-­checking means (10) comprises means (e.g., 90, 94, 96, and 101 of 10) for generating a trip signal (at 25) after a decision-delay interval (e.g., see 97 of FIG. 3) if a control signal (at 88) is present after the decision-delay interval.
Claim 5
Dependent Claim 41 words
The control circuit of claim 1 wherein said current-­sensing means (24) comprises a magnetizable device (24 in FIG. 2) and said validity-checking means (10) comprises means (90, 94, 96, and 101 of 10) for determining whether said magnetizable device is saturated.
Claim 6
Dependent Claim 44 words
The control circuit of claim 1 wherein said detecting means (15) generates a control signal (at 88) only during the time when predetermined current parameters (e.g., at 68, 69, and 70 of 16 - FIG. 2) are satisfied in said sensed-current signal (at 20).
Claim 7
Dependent Claim 50 words
The control circuit of claim 5 wherein said validity-­checking means (10) further comprises means (90, 94, 96, and 101 of 10) for generating said trip signal (at 25) if said control signal (at 88) is being generated after the load presented to the sensed-­current signal (at 20) has been changed.
Claim 8
Dependent Claim 114 words
A control circuit (15,10) for detecting the presence of overcurrent conditions comprising: magnetizable current-sensing means (24) responsive to the current in a line (202) for providing a sensed-current signal (at 20) that represents the current in the line (22); and means (15) responsive to said sensed-current signal for detecting overcurrent conditions and for generating a control signal (at 88), the control circuit being characterized by validity-checking means (10) responsive to said control signal (at 88) for determining whether or not said sensed-current signal (at 20) accurately represents the current in the line(at 22), said validity-checking means comprising means for generating a trip signal (at 25) if said magnetizable current-sensing means (24) is not saturated.
Claim 9
Dependent Claim 114 words
A control circuit (15,10) for detecting the presence of overcurrent conditions comprising: magnetizable current-sensing means (24) responsive to the current in a line (202) for providing a sensed-current signal (at 20) that represents the current in the line (22); and means (15) responsive to said sensed-current signal for detecting overcurrent conditions and for generating a control signal (at 88), the control circuit being characterized by validity-checking means (10) responsive to said control signal (at 88) for determining whether or not said sensed-current signal (at 20) accurately represents the current in the line(at 22), said validity-checking means comprising means for generating a trip signal (at 25) if said magnetizable current-sensing means (24) is not saturated.

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