Fuse loss indicating circuit
First Claim
1. In an SCR motor bridge circuit including a power source, at least one fuse for limiting the amount of current supplied by the power source to a motor, a gate circuit for supplying gating signals to the SCR'"'"'s, and a normally closed motor contactor for supplying power to the motor armature, a fuse loss monitoring and protection circuit comprising:
- optical isolator means coupled to monitor the one fuse for generating a set signal when the one fuse has opened;
latching means responsive to said set signal for generating a fuse loss signal;
indicator means responsive to said fuse loss signal for indicating that the one fuse has opened; and
protection means responsive to said fuse loss signal for generating a first disable signal to the gate circuit for disconnecting the gate circuit for supplying the gating signals from the SCR'"'"'s and for generating a second disable signal to the motor contactor for opening the motor contactor.
1 Assignment
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Accused Products
Abstract
The present invention relates to a fuse loss indicating system for monitoring the condition of a plurality of fuses in an electric circuit. The indicating system includes a plurality of individual indicator circuits, one for each fuse to be monitored. Each indicator circuit includes an optical isolator for electrically isolating the indicator circuit from the monitored circuit. When a monitored fuse blows, the associated optical isolator triggers a flip flop to generate a fuse loss signal to cause a warning LED to light and alert an operator as to which fuse has blown. In its preferred embodiment, the fuse loss indicating system is utilized to monitor the fuses in an SCR motor bridge circuit. In this embodiment, the fuse loss system also generates a bridge disable signal when a fuse blows to cause a bridge lockout circuit to disable the gating signals to the SCR'"'"'s, thereby disconnecting power from the motor.
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Citations
3 Claims
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1. In an SCR motor bridge circuit including a power source, at least one fuse for limiting the amount of current supplied by the power source to a motor, a gate circuit for supplying gating signals to the SCR'"'"'s, and a normally closed motor contactor for supplying power to the motor armature, a fuse loss monitoring and protection circuit comprising:
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optical isolator means coupled to monitor the one fuse for generating a set signal when the one fuse has opened; latching means responsive to said set signal for generating a fuse loss signal; indicator means responsive to said fuse loss signal for indicating that the one fuse has opened; and protection means responsive to said fuse loss signal for generating a first disable signal to the gate circuit for disconnecting the gate circuit for supplying the gating signals from the SCR'"'"'s and for generating a second disable signal to the motor contactor for opening the motor contactor. - View Dependent Claims (2, 3)
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Specification