Detecting Sheared Motor Shaft
When several motors are used to drive an equipment section composed of several mechanically coupled rolls, loosing one motor will cause a redistribution of the load among the remaining motors. This can become an issue if the necessary load exceeds the remaining motor capacity.
Among the 225 KPIs calculated every 10 min., the relative motor current level KPIs enable us to detect any change in the load distribution among motors driving physically coupled loads.
In this specific case, the shaft between the gear box and the center press roll sheared while none of the load of the remaining motors reached the level required to trigger an alarm.
The SPN continuous and automated data analysis system detected the shift in load distribution and alerted the mill and triggered our experts’ attention.
Further diagnostic led our experts to conclude that the source of the change in motor load was a broken drive train.
Exchanges with the mill confirmed that the jack shaft of one of the motors was sheared.
The mill began securing all the parts and manpower to correct the situation. Meanwhile, the other motor temperatures of the machine section were closely monitored.
Early detection of this issue allowed the mill to take precautionary measures to protect the machine section and the motors as well as to immediately plan parts and resources for an orderly repair work.
In the absence of the above diagnostic, difficulties in restarting the machine section would have resulted in tremendous production losses (in the millions) and significant costs resulting from unnecessary repairs.