Apparatus to sense a silicon controlled rectifier short circuit
First Claim
1. An apparatus to sense an SCR short circuit failure comprising:
- a detector circuit configured to sense each voltage of a poly-phase input and generate a fault signal upon substantially simultaneous detection of a zero-cross voltage condition for each phase of the poly-phase input; and
a control circuit configured to receive the fault signal of the detector circuit and generate an output to interrupt current flow through each SCR.
1 Assignment
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Accused Products
Abstract
An apparatus to sense an SCR short circuit failure and prevent overheating of solid-state power supply equipment, such as a welder, during an occurrence of the short circuit failure is provided. The apparatus includes a detector circuit capable of sensing a short circuit of an SCR in the power supply equipment. The detector circuit senses each voltage of a poly-phase input and generates a fault signal upon substantially simultaneous detection of a zero-cross voltage condition for each phase of the poly-phase input. A control circuit is configured to receive the fault signal of the detector circuit and generate an output to prevent fault current flow through to power supply equipment.
14 Citations
25 Claims
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1. An apparatus to sense an SCR short circuit failure comprising:
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a detector circuit configured to sense each voltage of a poly-phase input and generate a fault signal upon substantially simultaneous detection of a zero-cross voltage condition for each phase of the poly-phase input; and
a control circuit configured to receive the fault signal of the detector circuit and generate an output to interrupt current flow through each SCR. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system to detect a short circuit of an SCR in a welder, the system comprising:
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an electric current regulator for controlling electric current flow in a welder and configured to receive a three-phase power supply input;
a three-phase transformer connected to the electric current regulator and capable of transforming the three-phase power supply input into three single-phase detector inputs;
a plurality of SCRs configured to receive the three single phase detector inputs and generate a welder output; and
a detector circuit configured to receive the three single phase detector inputs and create a fault condition output signal capable of preventing electric current flow through the electric current regulator if any one of the SCRs is shorted. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of sensing an SCR short comprising:
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sensing input voltage to a plurality of SCRs; and
comparing the input voltage sensed at each SCR and if each input voltage is within a common given range at a substantially similar time, then interrupting line input voltages to the plurality of SCRs. - View Dependent Claims (19, 20, 21, 22, 23)
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24. An apparatus for detecting an SCR short circuit condition in a welder comprising:
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means for controlling electric current flow through at least one silicon controlled rectifier;
means for sensing instantaneous voltages of each single phase input; and
means for generating an output signal to interrupt the means for controlling electric current flow when each of the sensed instantaneous voltages is in a common specified voltage range. - View Dependent Claims (25)
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Specification