With regard to these problems such as high failure rates and heavy maintenance workload occurred in control of the old pressure-regulating and speed-regulating motor for the 210 t metallurgical casting crane in the steelmaking plant,upgrading the frequency conversion for the crane was carried out.Specifically,all wound-type motors for various mechanisms to the crane were transformed into variable-frequency motors,which did not need maintenance of carbon brushes and slip rings.And furthermore,the phase conversion and accelerating contactors were re-moved.Therefore,variable-frequency starting or stopping speed was stable and smooth,which ex-tended the service life of mechanical equipment,improved the motor efficiency and energy waste was avoided.After upgrading,the system failure rate was reduced by about 80％,and annual com-prehensive costs of approximately 267.5 thousand yuan could be saved.
维普
万方数据