Method for detecting insufficient contact pressure in a switching unit, device for implementing such a method, and switching unit including such a device

Abstract

A method for detecting insufficient contact pressure between two contacts of an electrical switching unit, including a device for resetting a mechanism for controlling the switching unit following a closure maneuver of the mechanism, the resetting device including a motor configured to complete the closure maneuver of the control mechanism. The method involves detecting whether the motor completes the closure and whether a resetting torque corresponds to a normal resetting torque, by analyzing an envelope curve of current consumed by the motor over time, and, if the motor completes the closure, deducing that a wear is a result of wear in the mechanism or a kinematic chain, and if the motor completes the closure and the resetting torque corresponds to an abnormal rescuing torque, deducing that the wear corresponds to wear in the motor or parts involved in compressing the closure spring.

Claims

1. A method for detecting insufficient contact pressure between two contacts of an electrical switching unit, said electrical switching unit comprising means for resetting a control mechanism for controlling the electrical switching unit following a closure maneuver of the control mechanism, said resetting means comprising means for compressing a closure spring intended to bring the control mechanism for controlling the electrical switching unit to a position in which the control mechanism is ready to close, and a motor configured to complete the closure maneuver of the control mechanism in an event of incomplete closure by said control mechanism and before carrying out the resetting as a result of said insufficient contact pressure being a result of wear in one of the control mechanism, a kinematic chain, the motor, and parts involved in compressing the closure spring, or in an event of incomplete closure exclusive of any wear, the method comprising: detecting whether the motor completes the closure maneuver and whether a resetting torque corresponds to a normal resetting torque by analyzing an envelope curve of current consumed by the motor over time in order to carry out the resetting following the closure maneuver of the control mechanism; if the motor completes the closure, deducing that the wear is the result of wear in one of the control mechanism and the kinematic chain; and if the motor completes the closure and if the resetting torque corresponds to an abnormal resetting torque, deducing that the wear corresponds to wear in one of the motor and the parts involved in compressing the closure spring.

2. The detection method according to claim 1, wherein it is detected that the motor has completed the closure by analyzing the envelope curve of current consumed by the motor over time, in order to carry out the resetting following the closure maneuver of the control mechanism, and by verifying whether a duration of said current has increased compared to a normal duration, corresponding to complete closure, with this increase in the duration of the current being characteristic of wear in the control mechanism, the kinematic chain, or of incomplete closure exclusive of any wear.

3. The detection method according to claim 2, wherein the envelope curve of current consumed by the motor for the resetting is compared with a standard curve, corresponding to the envelope curve of current consumed by the motor when the closure maneuver carried out by the control mechanism is complete, and it is thereby deduced whether or not the closure has been completed.

4. The detection method according to claim 2, wherein a range of duration of the current passing through the motor is defined and, for any current duration found within this range, it is deduced that there is normal operation without wear in the motor and in specific parts of the mechanism for compressing the closure spring.

5. The detection method according to claim 1, wherein it is detected that the motor encounters a normal or particularly high resetting torque by analyzing the envelope curve of current consumed by the motor over time, in order to complete the resetting following the closure maneuver of the control mechanism, and by verifying whether a current level has increased compared to a normal level corresponding to a case whereby there is neither wear in the motor nor wear in specific parts of the mechanism involved in compressing the closure spring.

6. The detection method according to claim 5, wherein an envelope is defined that is delimited by two end curves, and any envelope curve of current located between these two envelope curves expresses normal operation of the motor and of the parts involved in compressing the closure spring.

7. A detection device for implementing a method according to claim 1, wherein said detection device comprises current detection means that is connected to means for powering the motor, and a processing algorithm configured to compare the envelope curve of current consumed by the motor for the resetting, over time, with a normal curve, corresponding to at least one of complete closure maneuver carried out by the control mechanism and a normal resetting torque.

8. The detection device according to claim 7, wherein said detection device comprises current detection means that are connected to the means for powering the motor, and a processing algorithm able to compare the envelope curve of current consumed by the motor for the resetting, over time, with at least one of two end envelope curves and a normal range of duration, and configured to determine whether this envelope curve of consumed current is found within or even outside the envelope, or even whether a current duration is found within or outside the range.

9. The detection device according to claim 7, wherein said resetting means comprises means for storing a closure energy in the control mechanism.

10. The detection device according to claim 7, wherein said detection device comprises means for locally or remotely indicating a detection of one of wear conditions.

11. An electrical switching unit, wherein said electrical switching unit comprises the detection device according to claim 7.

12. The electrical switching unit according to claim 11, wherein said electrical switching unit is an OCO circuit breaker, comprising means for resetting the control mechanism of the circuit breaker that is configured to return the control mechanism to a position in which said control mechanism is ready to close, following a closure maneuver.

Description

DESCRIPTION OF THE FIGURES

(1) FIGS. 1 to 3 are three graphical representations showing curves representing the current consumed by the motor during the resetting on the basis of the resetting duration;

(2) FIG. 1 is an envelope curve showing the current consumed by the motor during the resetting on the basis of the resetting duration, during normal operation of the switching unit;

(3) FIG. 2 shows two curves, one of which corresponds to normal operation of the unit, and the other one of which corresponds to incomplete closure of the contacts of the unit; and

(4) FIG. 3 shows two curves, one of which corresponds to normal operation, and the other one of which corresponds to a high resetting torque.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS OF THE INVENTION

(5) FIG. 1 shows an envelope curve representing the current consumed by a motor, said motor being intended to carry out the resetting of a mechanism for controlling the contacts of a switching unit, such as a medium voltage circuit breaker, on the basis of the duration of this resetting.

(6) More specifically, these resetting means comprise means for storing the closure energy in the control mechanism so as to bring this control mechanism to a position in which it is ready to close the contacts of the unit. Advantageously, these resetting means comprise a closure spring.

(7) In FIG. 2, the first curve 1 corresponds to normal operation without any wear inside the switching unit, whereas the second curve 2 corresponds to incomplete closure of the contacts of the unit following wear in the mechanism, the kinematic chain, or even incomplete closure of the contacts of the unit exclusive of any wear, such as incomplete closure following use at low temperature.

(8) As shown in this FIG. 2, the resetting duration d2 is higher in the case of the second curve 2, corresponding to incomplete closure of the contacts, than in the case of the first curve 1, corresponding to normal operation of the unit.

(9) In FIG. 3, the curve 3 corresponds to normal operation of the unit, whereas the curve 4 corresponds to a switching unit exhibiting wear in the motor or specifically in the parts of the mechanism for compressing the closure spring. Thus, it appears that, in the curve 4, the maximum level n2 of current consumed by the motor is higher than the level n1 in the curve 3.

(10) In a first embodiment of the method according to the invention, as shown in FIG. 2, incomplete closure is detected, which is characteristic of wear in the control mechanism, the kinematic chain of the switching unit, or even of incomplete closure exclusive of any wear, such as that following use at low temperature, by comparing the two curves 1 and 2, and by detecting a resetting duration d2 that is greater than that of d1 usually observed during normal operation of the device.

(11) According to a second embodiment (not shown) of the method according to the invention, a range, or even an interval of two resetting current duration values, is defined, and the resetting duration d2 corresponding to the analysed curve is compared with this range or scope.

(12) Similarly, as shown in FIG. 3, an abnormally high resetting torque is detected by comparing two curves, respectively representing, on the one hand, the resetting current on the basis of the resetting time, during normal operation of the unit, and, on the other hand, the resetting current on the basis of the resetting time when wear is present in the motor or specifically in the parts of the mechanism for compressing the closure spring, and by detecting a difference between the two maximum current levels n1, n2.

(13) According to another embodiment, not shown, an envelope is defined that is delimited by two envelope curves of current, called end curves, and any envelope curve of current found within this envelope between these two envelope curves expresses normal operation of the motor and of the parts involved in compressing the closure spring.

(14) The detection device according to a particular embodiment of the invention comprises current detection means connected to the means for powering the motor, and a processing algorithm able to compare the envelope curve of current consumed by the motor for the resetting operation, over time, with an envelope curve corresponding to normal operation of the unit, or even with the two aforementioned end envelope curves, and able to determine whether this envelope curve of consumed current is within or even outside the aforementioned envelope, or even able to compare the resetting duration with the aforementioned normal range of duration, and able to determine whether this current duration is found within or outside the range.

(15) The present invention thus allows detection of any incomplete closure manoeuvre of a circuit breaker that can affect the performance of the unit and the safety of individuals.

(16) Of course, the invention is not limited to the embodiments described and illustrated herein, which have been provided solely by way of an example.

(17) On the contrary, the invention includes all the technical equivalents of the means described herein, as well as their combinations, if they are produced according to the spirit of the invention.