Monitoring system for high-voltage switches
AssigneeABB Technology AG
InventorsMarek Hagel, Patrick Fehlmann
Life of this patent
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Abstract
A method and an apparatus are disclosed for measuring contact erosion in an electrical switching device by a dynamic resistance measurement (DRM). To determine an overlap time and a contact erosion in an exemplary switching device, a change in current across the switching device can be measured indirectly by a measurement current being passed across the switching device and a parallel conductor, the change in current in the parallel conductor being measured. Exemplary embodiments relate, to the following: detection of a differential current measurement signal in the parallel conductor with the aid of a Rogowski coil; and selection of a parallel conductor resistance on an order of the switch resistance.
Claims20
A method for measuring contact erosion in an electrical switching device, which has a rated current path having a rated current contact system, and a consumable contact current path having a consumable contact system, an overlap time between the separation of the rated current contacts and of the consumable contacts being measured from a change in resistance when the rated current contacts and the consumable contacts are separated, and erosion of the consumable contacts being determined from this, comprising:
- a) branching a first current and a second current from a feed current of a measurement current source;
- b) passing the first current through the switching device, and passing the second current in parallel with the switching device;
- and
- c) detecting the second current with the aid of a measurement system, and determining the overlap time from a change in the second current as a function of time.
A measurement system for measuring contact erosion in an electrical switching device, which has a rated current path having a rated current contact system, and a consumable contact current path having a consumable contact system, the measurement system, comprising:
- a measurement current source, a sensor, and an evaluation unit, which serve for measuring resistance across the switching device as a function of time, for determining an overlap time between a separation of rated current contacts and consumable contacts, and for determining erosion of the consumable contacts;
- and
- a parallel conductor provided in parallel with the switching device, the sensor being arranged on the parallel conductor, wherein
- the measurement current source is connected to the switching device for feeding a first current, and to the parallel conductor for feeding a second current;
- and
- the sensor detects the second current, the evaluation unit having means for determining the overlap time from a change in the second current as a function of time.
Dependencies are inferred from the claim text.