Protective system against commutation failure in a chopper circuit
First Claim
1. A protective system against a commutation failure in a chopper circuit provided for controlling the speed of an electric motor, said system comprising:
- protective circuit means including means associated with the chopper circuit for detecting a commutation failure in said chopper circuit and means responsive to said commutation failure detecting means for breaking the main circuit including said electric motor from a power supply when a commutation failure takes place in said chopper circuit; and
means associated with said protective circuit means for certifying the validity of said protective circuit means in such a manner that said certifying means applies a checking signal to said commutation failure detecting means when the check of the validity of said protective circuit means is required at any time desired, said checking signal being selected to correspond to a signal applied from said chopper circuit to said commutation failure detecting means when an actual commutation failure takes place in said chopper circuit.
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Accused Products
Abstract
In a thyristor chopper circuit used for the control of the rotational speed of an electric motor and provided with a protective system for preventing problems caused by a commutation failure in the chopper circuit, the protective system is provided with means for detecting the occurrence of commutation failure and means for certifying the operative condition or validity of the commutation failure detecting means. The operative condition certifying means is provided with means for supplying the commutation failure detecting means with a checking signal corresponding to a signal which is applied to the commutation failure detecting means upon the occurrence of the commutation failure so that whether the protective system is in a normally operative or valid condition can be certified at any time desired.
21 Citations
11 Claims
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1. A protective system against a commutation failure in a chopper circuit provided for controlling the speed of an electric motor, said system comprising:
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protective circuit means including means associated with the chopper circuit for detecting a commutation failure in said chopper circuit and means responsive to said commutation failure detecting means for breaking the main circuit including said electric motor from a power supply when a commutation failure takes place in said chopper circuit; and means associated with said protective circuit means for certifying the validity of said protective circuit means in such a manner that said certifying means applies a checking signal to said commutation failure detecting means when the check of the validity of said protective circuit means is required at any time desired, said checking signal being selected to correspond to a signal applied from said chopper circuit to said commutation failure detecting means when an actual commutation failure takes place in said chopper circuit. - View Dependent Claims (2, 3, 6, 7, 8, 9)
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4. A protective system against a commutation failure in a chopper circuit provided for controlling the speed of an electric motor, said system comprising:
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protective circuit means including means associated with said chopper circuit for detecting a commutation failure in said chopper circuit and circuit breaker means responsive to said commutation failure detecting means for cutting off said motor from a power supply; means for certifying the validity of said protective circuit means, said certifying means including means for applying a checking signal in response to the closure of said circuit breaker means to said commutation failure detecting means for a predetermined period of time which is determined by time limit circuit means, said checking signal being selected to correspond to a signal applied to said commutation failure detecting means when an actual commutation failure takes place; and means responsive to the output of said commutation failure detecting means when said checking signal is applied thereto for indicating the validity of said protective circuit means. - View Dependent Claims (5, 10, 11)
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Specification