Method for detecting insufficient contact pressure in a switch unit and device for implementing the method

Abstract

The invention relates to a method for detecting an insufficient contact pressure between two contacts of an electrical switching unit, the unit comprising means for resetting the mechanism after closing of a mechanism for controlling the switching unit, the resetting means comprising an electric motor capable of completing a closing operation of the control mechanism in the case of an incomplete closing by the control mechanism and before resetting or in the case of an incomplete closing without any wear, the insufficient contact pressure being caused by wear in the mechanism, the kinematic chain, the motor, the parts involved in compressing the closing spring. The method consists in detecting, by analyzing the envelope curve of the current consumed by the motor over time, whether the motor has completed closing and / or whether the resetting torque corresponds to a resetting torque called the normal resetting torque to perform the resetting after the closing operation of the control mechanism, and if the motor has completed closing, inferring that the wear is caused by wear in the mechanism, the kinematic chain or even the motor.

Description

Technical Field

[0001] The invention relates to a method for detecting an insufficient contact pressure between two contacts of an electrical switching unit, the unit comprising means for resetting a mechanism for controlling the switching unit after the mechanism has been closed, the means comprising means for compressing a closing spring intended to bring the mechanism for controlling the unit to a position in which it is ready to close, the resetting means also comprising an electric motor capable of completing the closing operation of the control mechanism in the event of an incomplete closure by the control mechanism and of being reset before execution or in the event of an incomplete closure that does not involve any wear (for example in periods of low temperatures that cause grease to freeze), the insufficient contact pressure being caused by wear in the mechanism, in the kinematic chain, in the electric motor, in the components involved in compressing the closing spring.

[0002] The invention also relates to a detection device for implementing the method and a switching unit, such as a circuit breaker, comprising such a device. Background Art

[0003] A device for operating a circuit breaker is known, such as the one disclosed in document EP0221430, which allows to perform rapid cycles to open, close and reopen the circuit breaker, generally called OCO, the circuit breaker comprising a set of fixed contacts and a set of movable contacts, an operating rod for connection to said set of movable contacts, a first spring (which, when expanded, transmits a movement to the rod in a direction corresponding to the opening of the circuit breaker), a second spring (which, when expanded, transmits a movement to the rod in a direction corresponding to the closing of the circuit breaker), said device comprising means for ensuring that the expansion of the second spring causes the resetting of the first spring, each of said springs being connected to a controllable locking member.

[0004] In such circuit breakers, the control mechanism always has to be reset after closing.

[0005] These units may be subject to various phenomena such as very intensive use, corrosion, low temperature use, etc. These conditions lead to ageing of the unit, in particular wear of the mechanisms, kinematic chains, electric motors or in particular of the components used to compress the closing spring.

[0006] Such wear in the machinery, kinematic chains or low temperature use will result in incomplete closure of the contacts of the unit during operation of the closing unit. This incomplete closure results in partial contact pressure in the vacuum tube and more generally in the switch components.

[0007] When the mechanism is of the OCO cam type, i.e. a mechanism that allows to perform a fast closing of the unit (0.3 seconds) after opening the unit, wherein the mechanism comprises a cam transmission between the shaft connected to the closing spring and the shaft connected to the kinematic chain part driving the movable contact, and when the closing of the mechanism is incomplete, the closing is completed by the motor during the reset after the closing. This does not cause problems when such closing is performed at nominal current. If the current is higher, the presence of such partial contact pressure before the closing is completed by the motor can lead to overheating or even destruction (if the current level reaches the allowed short duration level or if there is a short circuit).

[0008] When resetting is not performed by the motor, the above-mentioned problems caused by incomplete closing may occur even during closing at the nominal current.

[0009] It is important to detect the aforementioned wear and incomplete closure as this serves to indicate the need to perform maintenance and / or better protect the unit from environmental conditions.

[0010] Known switching units include means for providing information about the actual path of the movable contact, which allows the presence of wear in the contact to be detected and the information to be transmitted locally, in particular by optical signal means, or remotely by electrical signals. However, these means do not allow the detection of the above-mentioned wear and incomplete closure of the contacts. Summary of the invention

[0011] The present invention overcomes these problems and proposes a method for detecting wear in a mechanism, a kinematic chain, a motor or a component for compressing a closing spring, and incomplete closing, which method allows distinguishing between wear in the mechanism, the kinematic chain, an incomplete closing not comprising any wear, and wear in a specific component of the motor or the mechanism for compressing the closing spring.

[0012] Another object of the invention is a device for implementing the method and an electrical switching unit comprising such a device.

[0013] To this end, the object of the present invention is a method for detecting insufficient contact pressure between two contacts of an electrical switching unit of the above-mentioned type, the method being characterized in that it comprises detecting, by analyzing the envelope curve of the current consumed by the motor over time, whether the motor has completed closing and / or whether the reset torque corresponds to a reset torque called a normal reset torque to perform resetting after a closing manipulation of a control mechanism, and if the motor has completed closing, inferring that the wear is caused by wear in the mechanism, the kinematic chain or even the motor, and / or if the reset torque corresponds to an abnormal reset torque, inferring that the wear corresponds to wear in the motor or even in a component involved in compressing a closing spring.

[0014] According to a particular feature, if the motor has completed closing, it is detected by analyzing the envelope curve of the current consumed by the motor over time to perform a reset after the closing manipulation of the control mechanism, and by verifying whether the duration of this current is increased compared to the current duration called normal duration corresponding to complete closure, wherein this increase in the current duration is a characteristic of wear in the mechanism, the kinematic chain or a characteristic of an incomplete closure that does not include any wear.

[0015] It should be noted that the kinematic chain includes components that are located between the mechanism and the contacts, and that transmit the motion provided by the mechanism to the movable contact.

[0016] According to another feature, if the motor encounters a normal or particularly high resetting torque, this is detected by analyzing the envelope curve of the current consumed by the motor over time to complete the resetting after the closing operation of the control mechanism, and by verifying whether the current level is increased compared to a current level called a normal level corresponding to a situation where there is no wear in the motor and no wear in the specific parts of the mechanism involving the compression of the closing spring.

[0017] According to another feature, the envelope curve of the current consumed by the motor for the reset operation is compared with an envelope curve of the current, called a standard curve, corresponding to the envelope curve of the current consumed by the motor when the closing performed by the control mechanism is completed, thereby deducing whether the closing has been completed.

[0018] According to another feature, a range of durations of the current through the motor is defined and for any current duration within this range it is inferred that there is normal operation without wear in the motor and in specific parts of the mechanism for compressing the closing spring.

[0019] According to another feature, an envelope is defined which is bounded by two envelope curves of the current called end curves, and any envelope curve of the current within this envelope lying between these two envelope curves represents normal operation of the motor and of the components involved in compressing the closing spring.

[0020] Another object of the invention is a detection device for implementing a method comprising the aforementioned characteristics alone or in combination, said device being characterized in that it comprises current detection means connected to means for powering an electric motor, and a processing algorithm capable of comparing the envelope curve of the current consumed over time by the electric motor for resetting with the envelope curve of the current, called normal curve, corresponding to the full closing and / or normal resetting torque executed by the control member.

[0021] According to another feature, the device comprises current detection means connected to the means for powering the electric motor, and a processing algorithm capable of comparing the envelope curve of the current consumed over time by the electric motor for resetting with the above-mentioned two terminal envelope curves and / or with the above-mentioned normal duration range and capable of determining whether this envelope curve of the consumed current is within the above-mentioned envelope or even outside it or even whether the current duration is within or outside this range.

[0022] According to another feature, the aforementioned resetting device comprises means for storing closing energy in the control member.

[0023] According to another feature, the device comprises means for indicating, locally or remotely, the detection of one of the above-mentioned wear conditions.

[0024] Another object of the invention is an electrical switching unit, said unit being characterized in that it comprises detection means comprising the above-mentioned features, alone or in combination.

[0025] According to another feature, the unit is a circuit breaker of the OCO type, comprising means for resetting the control mechanism of the circuit breaker, said means being able to return the mechanism to its ready-to-close position after a closing operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] However, other advantages and features of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, which are provided by way of example only, in which:

[0027] - Figures 1 to 3 are three graphical representations showing curves representing current consumed by the motor during a reset based on the reset duration;

[0028] - Figure 1 is an envelope curve showing the current consumed by the motor during the reset period based on the reset duration during normal operation of the switching unit;

[0029] - Figure 2 Two curves are shown, one corresponding to normal operation of the cell and the other corresponding to incomplete closure of the cell contacts; and

[0030] - Figure 3 Two curves are shown, one corresponding to normal operation and the other corresponding to a high reset torque. DETAILED DESCRIPTION

[0031] Figure 1 Shown is an envelope representing the current consumed by a motor for performing a reset of a mechanism for controlling contacts of a switching unit, such as a medium voltage circuit breaker, based on the duration of this reset.

[0032] More specifically, these resetting means comprise means for storing closing energy in the control mechanism in order to bring the control mechanism to a position ready to close the unit contacts. Advantageously, these resetting means comprise a closing spring.

[0033] exist Figure 2 In the diagram, the first curve 1 corresponds to normal operation without any wear in the switching unit, while the second curve 2 corresponds to incomplete closure of the unit contacts after wear in the mechanism, the motion chain, or even without any wear, such as after use at low temperatures.

[0034] If the Figure 2 As shown, the reset 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.

[0035] exist Figure 3 In the example shown in Fig. 3, curve 3 corresponds to normal operation of the unit, while curve 4 corresponds to a switching unit showing wear in the motor or in particular in the components of the mechanism for compressing the closing spring. It can thus be seen that in curve 4, the maximum level n2 of the current consumed by the motor is higher than the level n1 in curve 3.

[0036] In a first embodiment of the method according to the invention, Figure 2 As shown, an incomplete closure is detected, which is characteristic of wear in the control mechanism, the kinematic chain of the switching unit, or even an incomplete closure that does not include any wear, for example after use at low temperatures, by comparing the two curves 1 and 2 and by detecting a reset duration d2 (which is greater than the reset duration d1 usually observed during normal operation of the device).

[0037] According to a second embodiment of the method according to the invention (not shown), a range or even an interval between two reset current duration values ​​is defined and the reset duration d2 corresponding to the analyzed curve is compared with this range or interval.

[0038] Similarly, if Figure 3 As shown, an abnormally high reset torque is detected by comparing two curves, which respectively represent on the one hand the reset current based on the reset time during normal operation of the unit and on the other hand the reset current based on the reset time when there is wear in the motor or in particular in the components of the mechanism for compressing the closing spring, and by detecting the difference between two maximum current levels n1, n2.

[0039] According to another embodiment not shown, an envelope is defined which is bounded by two current envelope curves, called end curves, and any current envelope curve within this envelope between these two envelope curves represents normal operation of the motor and the components involved in compressing the closing spring.

[0040] According to a particular embodiment of the invention, the detection device comprises a current detection device connected to the device for powering the electric motor, and a processing algorithm capable of comparing over time the envelope curve of the current consumed by the electric motor for the reset operation with the envelope curve corresponding to the normal operation of the unit or even with both envelope curves mentioned above, and capable of determining whether the envelope curve of the consumed current is within the above-mentioned envelope or even outside it, or even capable of comparing the reset duration with the above-mentioned normal duration range, and capable of determining whether the current duration is within or outside this range.

[0041] The invention thus allows detecting any incomplete closing manipulation of the circuit breaker, which could affect the performance of the unit and the safety of the individuals.

[0042] Of course, the invention is not limited to the embodiments described and shown here, which are provided merely as examples.

[0043] On the contrary, the invention includes all technical equivalents of the devices described herein and their combinations, provided that they are produced in accordance with the spirit of the invention.

Claims

1. A method for detecting an insufficient contact pressure between two contacts of an electrical switching unit, the unit comprising means for resetting a mechanism for controlling the switching unit after the mechanism has been closed, the resetting means comprising means for compressing a closing spring intended to bring the mechanism for controlling the unit into a position in which it is ready to close, the resetting means also comprising an electric motor capable of completing the closing operation of the control mechanism in the event of an incomplete closing by the control mechanism and before performing a reset or in the event of an incomplete closing not comprising any wear, the insufficient contact pressure being caused by wear in the mechanism, in the kinematic chain, in the electric motor, in the components involved in compressing the closing spring, It is characterized in that It includes detecting whether the motor has completed closing and / or whether the reset torque corresponds to a reset torque called a normal reset torque by analyzing the envelope curve of the current (2, 4) consumed by the motor over time to perform reset after the closing operation of the control mechanism, and if the motor has completed closing, inferring that the wear is caused by wear in the mechanism, the kinematic chain or the motor, and / or if the reset torque corresponds to an abnormal reset torque, inferring that the wear corresponds to wear in the motor or a component of a compression closing spring; If the motor has completed closing, it is detected by analyzing the envelope curve of the current (2) consumed by the motor over time to perform a reset after the closing operation of the control mechanism, and by verifying whether the duration of this current (d2) increases compared to the current duration, called normal duration (d1), corresponding to complete closing, wherein this increase in the current duration is a characteristic of wear in the mechanism, the kinematic chain, or a characteristic of an incomplete closure that does not include any wear.

2. The method according to claim 1, characterized in that If the motor encounters a normal reset torque or a reset torque higher than the normal reset torque, it is detected by analyzing the envelope curve of the current (4) consumed by the motor over time to complete the reset after the closing operation of the control mechanism, and by verifying whether the current level n2 increases compared to the current level n1 called the normal level corresponding to the situation where there is no wear in the motor and no wear in the specific parts of the mechanism involving the compression of the closing spring.

3. The method according to claim 1, characterized in that The envelope curve of the current (2) consumed by the motor for the reset operation is compared with the envelope curve of the current (1) called the standard curve corresponding to the envelope curve of the current consumed by the motor when the closing performed by the control mechanism is completed, thereby inferring whether the closing has been completed.

4. The method according to claim 1, characterized in that A range of durations of current through the motor is defined, and for any current duration within this range, it is inferred that normal operation exists without wear in the motor and in specific parts of the mechanism for compressing the closing spring.

5. The method according to claim 2, characterized in that: An envelope is defined which is bounded by two envelope curves of the current called end curves, and any envelope curve of the current within this envelope which lies between these two envelope curves represents normal operation of the motor and the components involved in compressing the closing spring.

6. A detection device, the detection device is used to implement the method according to any one of claims 1 to 5, characterized in that: It comprises current sensing means connected to the means for powering the electric motor, and a processing algorithm capable of comparing the envelope curve of the current consumed over time by the electric motor for resetting with the envelope curve of the current, called normal curve, corresponding to the full closing and / or normal resetting torque executed by the control mechanism.

7. The detection device according to claim 6, characterized in that: It comprises a current detection device connected to a device for powering an electric motor and a processing algorithm capable of comparing an envelope curve of the current consumed over time by the electric motor for resetting with two end envelope curves and / or with a normal duration range, and capable of determining whether this envelope curve of the consumed current is within or outside the envelope or whether the current duration is within or outside the range.

8. The detection device according to claim 6 or 7, characterized in that: The above-mentioned resetting device comprises means for storing closing energy in the control mechanism.

9. The detection device according to any one of claims 6 to 8, characterized in that: It includes means for indicating, locally or remotely, the detection of one of the above-mentioned wear conditions.

10. An electrical switch unit, characterized in that: It comprises a detection device according to any one of claims 6 to 9.

11. The electrical switching unit according to claim 10, characterized in that It is a circuit breaker of the OCO type comprising means for resetting the control mechanism of said circuit breaker, said means being able to return said mechanism to its ready-to-close position after a closing operation.

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