Motor drive with low leakage surge protection
AssigneeRockwell Automation Technologies, Inc.
InventorRangarajan M. Tallam
Life of this patent
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Abstract
A motor drive employs a combination of gas discharge tubes and metal oxide varistors to create precisely tailored surge protection that has a low leakage current minimizing the triggering of ground fault detection circuitry when multiple motor drives are attached to a single line source.
Claims20
A motor drive with integrated surge protection comprising:
- three-phase power line inputs receiving AC power;
- a rectifier unit communicating with the power line inputs and converting the AC power to a DC bus voltage;
- an inverter receiving the DC bus voltage to synthesize a motor drive current and from the DC bus voltage;
- a surge protection network providing an interconnection between each line input and ground and an interconnection between each line input and each other line input, the surge protection network controlling a maximum surge voltage across each interconnection, the surge protection network further providing a metal oxide varistor on each interconnection and at least one gas discharge tube between each line input and ground;
- and
- whereby low leakage current to ground is ensured.
A method of providing electrical protection to a motor drive of a type connected to three-phase power line inputs to receive AC power at a rectifier unit communicating with the power line inputs and converting the AC power to a DC bus voltage, and further having an inverter receiving the DC bus voltage to synthesize a motor drive current and from the DC bus voltage, the method the steps of:
- (a) providing an interconnection between each line input and ground;
- (b) providing an interconnection between each line input and each other line input;
- (c) controlling a maximum surge voltage across each interconnection with a metal oxide varistor on each interconnection and at least one gas discharge tube between each line input and ground;
- whereby low leakage current to ground is ensured.
Dependencies are inferred from the claim text.