Thermal Imaging Scan
Why Thermal Imaging?
In order to run thermal imaging diagnostics on electric motors, it is always best to use a good quality infrared cameras when the motors are running under normal operating conditions. That gives us baseline measurements of the temperature of the motor main components, such as motor stator, shaft coupling, motor and shaft bearings, and the gearbox.
When working with low electrical loads, the indications of a problem may be subtle. Thus a minimum of 40 % of design load is recommended and the higher the load, the better the resultant output. As a load increases, the temperature will increase too and if a problem exists, expect greater temperature differences at higher but rated for the motor loads.
All motors having the normal operating temperature listed on the nameplate. The exterior surface temperature is usually a good indicator of the internal temperature. As the motor gets hotter inside, it also gets hotter outside. When motor is overheating, the internal windings will start rapidly deteriorate. Every increase by 10°C above the designed operating temperature decreases the life of motor windings insulation by 50 percent.
An infrared image of the motor gives a good indication where the high temperature is coming from, i.e. windings, bearings or coupling. If a coupling is running warm it is an indicator of misalignment.
Three primary causes of abnormal thermal patterns are: high-resistance contact surface, Load imbalances and failed components.
Regular inspection routines that include thermal imaging of all critical motor and drive combinations and comparing those with baseline images will help to determine whether or not an apparent hotspot is unusual. This will also help to verify if the motor repairs were successful.