Mines safety alert no. 30 | 26 July 2000 | Version 1
Electric motor overheats
Investigations are ongoing and further information may be published as it becomes available. The information in this publication is what is known at the time of writing.
We issue Safety Notices to draw attention to the occurrence of a serious incident, raise awareness of risks, and prompt assessment of your existing controls.
Mine type
All mine types
Incident
Induction motor found with 40% of rotor bars broken causing the motor to loose torque, generate heat and run rough. The damage was caused by operators attempting repeated motor starts on a belt conveyor.
The repeated motor starts generated high internal heating in the rotor bars and windings that was not given time to dissipate before more attempts to start the motor were made.
Equipment
AC induction (electric) motor
Hazard
Excessive heat, noise, vibration and reduced starting torque
Cause
Excessive number of motor starts generated high internal temperatures
Comments and recommendations
It is recommended that the Site Mine Electrician/Electrical Supervisor either nominate the number of times each motor can be started each hour or automatically control the time between successive starts to allow heat generated to be safely dissipated.
Contact: Greg Lyne, minesafetyandhealth@dnrm.qld.gov.au
Issued by Queensland Department of Mines and Energy
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