| 摘要 |
PURPOSE: To provide overload protection with high accuracy and responsivity by detecting the torque of the shaft of a generator, comparing the detected torque with a set torque, and, if the detected torque is lager, tripping a circuit breaker. CONSTITUTION: When the load on a generator G driven by a motor P is increased, the speedωof the motor P is reduced, and further the torque T of the generator shaft, detected from signals of a sensor ST by a torque detecting circuit 1, is increased in inverse proportion to the speedω. When the detected torque T is larger than a set torque T set through a torque setting circuit 2, a comparison circuit 3 judges that as overloading and produces output to a trip command circuit 4. As a result, the trip command circuit 4 outputs a trip command to a circuit breaker CB, which is then tripped to protect the generator G from overload. Since the generator is protected from overload by directly detecting fluctuation in torque as the primary cause of overloading, as mentioned above, overload protection is accomplished with higher accuracy and responsivity, as compared with conventional schemes using secondary detection.
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