Application of Infrared Thermal Imager in Motor Inspection

Electric motors are the backbone of industry. According to estimates by the U.S. Department of Energy, there are 40 million motors operating in the industry in the United States alone. These motors consume 70% of the electricity consumed by the entire industry. This is enough to illustrate the importance of motors.　　 Incorporating thermal imaging into your company's maintenance plan as a motor condition monitoring technology to avoid costly failures can bring you great benefits. By using an infrared camera, you can capture the infrared temperature measurement value of the motor as a two-dimensional image.　　　　 The thermal image of the motor can reveal the operating conditions reflected by its surface temperature. This condition monitoring is an important method for avoiding motor failures in systems that are critical to production, business, and institutional processes. This kind of predictive measure is very important, because when the key system fails, it will inevitably increase costs, and need to redistribute workers and materials, thereby reducing production efficiency. If not corrected, the company’s profits will suffer and may Affect the safety of employees and customers.　　　　　　 Ideally, you should check the running motor under normal operating conditions. Unlike infrared temperature, which only collects temperature at a single point, a thermal imager can capture temperatures at thousands of points at a time for all key components: motors, couplings, motor and shaft bearings, and reducers.　　 Each motor runs at a specific internal temperature. The temperature of other parts should not be as high as the temperature of the motor housing. The standard operating temperature should be listed on the nameplate of all motors. Although the infrared imager cannot see the inside of the motor, the external surface temperature is sufficient to indicate the internal temperature. As the internal temperature of the motor increases, the temperature of its outer surface also increases. Therefore, experienced imaging personnel who are familiar with motors can use thermal imaging to identify abnormal conditions, such as insufficient air flow, imminent bearing failure, coupling problems, and deterioration of the motor stator or rotor insulation.　　 Generally speaking, it is a very good practice to design a regular inspection path that includes all key motor/drive combinations. After the inspection, save the thermal image of each device to the computer and track the measurement results over time. In this way, you will get a basic image that can be used for comparison, which can help you determine whether a hot spot is normal, and help you confirm whether the repair is effective after the repair.　　Equipment conditions with safety issues should have the highest priority for maintenance. The guidelines provided by NETA (International Electrical Testing Association) stipulate that when the temperature difference of similar components exceeds 15 °C (27 °F) under similar loads, repairs should be carried out immediately. The organization also recommends that when the temperature difference between the components and the ambient air exceeds 40 °C (72 °F), repairs should also be carried out immediately.　　　　　　 If you think that the overheating is caused by the following reasons, consider taking the measures introduced: 　　a Insufficient air flow. If the occurrence of a short production suspension does not affect the production process, turn off the motor long enough to clean the air inlet grille on a small scale. In the next planned plant shutdown, arrange a thorough motor cleaning.　　B Unbalanced voltage or overload. Common causes of overheating (high resistance in switch cabinets, circuit breakers or motor junction boxes) can generally be found through thermal imaging inspections and confirmed with a multimeter, clamp meter or power quality analyzer.　　C Impending bearing failure.　　 When the thermal image indicates an overheated bearing, a maintenance decision should be made to replace or lubricate the bearing. Although vibration analysis is expensive and requires an expert, it can usually help you determine the best course of action.　　D Insulation failure. If the impact on production is not significant, the motor should be operated at a lower rated value in accordance with the NEMA standard. Issue a job notice to replace the motor as soon as possible.　　 The e axis is not aligned. In most cases, an unaligned coupling can be confirmed through vibration analysis. If the motor can be turned off, the dial of the laser alignment device can be used to correct the misalignment condition.　　　　　　 Whenever a problem is found with the thermal imager, please use the relevant software to record the result in a report, including a thermal image and digital image of the device. This is the best way to report the problems you find and suggest repairs