Fail transistor detection and display system for electrical discharge machining apparatus
AssigneeColt Industries Inc.
InventorsKuang-Ta Ho, Oliver A. Bell, Jr.
Life of this patent
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Abstract
An EDM circuit that detects power transistor switch failure. A comparator 62 and a sample and hold stage 60 are used during a window of time formed by the off-time of a pulse generator to determine whether power switch MOSFET 30 is conducting. If MOSFET 30 is conducting during the off-time of the pulse generator LED 72 will emit light to indicate a failed power transistor switch.
Claims6
In an electrical discharge machining apparatus including an electronic power switch and a power supply connected to a gap and a drive circuit for periodically turning said switch on and off for providing machining power pulses to the gap, a system for detecting power switch failure, comprising:
- detecting means coupled to said electronic switch for responding to its conduction;
- means for keying the operation of said detecting means only during normal pulse off time of said power switch;
- indicating means operatively connected to the output of said detecting means for providing a visual failure signal responsive to conduction during normal off time.
Dependencies are inferred from the claim text.