Plant & Works Engineering May 2022

How planned maintenance increases the sustainability of electric motors Maintenance Matters Problem Solver 16 | Plant & Works Engineering www.pwemag.co.uk May 2022 E lectric motors account for up to 40% of electricity consumption worldwide and 70% of industrial electricity consumption. International regulations, such as the recent EU ecodesign requirements, help ensure that motors operate as sustainably as possible. However, underlying issues with motors, which often go unnoticed for long periods of time, can jeopardise these efforts and cause motors to consume more energy than necessary. To maximise a motor’s energy efficiency, monitoring it throughout its lifecycle is essential. Following an effective preventative maintenance plan and carrying out restorative work can help increase the length of time that a motor is in operation. Electric motors and the circular economy According to a recent paper titled, A Review of Circular Economy Research for Electric Motors and the Role of Industry 4.0 Technologies, to reach its goal of 80% reduction in carbon emissions by 2050, the UK needs to take immediate action to move towards a more resource-efficient circular economy. With electric motors, this can be approached in two ways: optimising their energy consumption and extending their lifespan to avoid contributing to waste. With older assets that are showing signs of slowing down, this can be tackled with regular maintenance and rewinding in specialist facilities. The importance of planning A wide range of tests can be performed as part of a robust preventative maintenance regime to analyse a motor’s efficiency. A thermal imaging analysis can be used to assess the condition of the bearings. This can determine whether there is wear on the bearings or if an individual bearing’s temperature is much higher than the others. Similarly, a vibration analysis test can indicate whether there are issues with the running gear. This way, broken components can be repaired or replaced without the need to buy an entirely new motor. Initially resistance tests can be performed to ensure the phases are balanced and continuity is present. Insulation Resistance tests can also be performed on offline motors to make sure the insulation quality is to a good standard and no breakdown to earth is present. On higher voltage machines, engineers would perform polarisation index tests over a ten-minute period to check if there is any contamination or moisture on the windings. Another test is high potential, which measures the voltage of the machine using the twice line voltage plus one thousand. The test stresses the insulation system and detects dielectric weaknesses to ensure the equipment can withstand unplanned surges. A surge test can then be performed which detects weaknesses or breakdowns in the interturn insulation. Based on the reports from these tests, engineers can suggest maintenance strategies and recommend the most appropriate interval for having the motors retested. Regular test reports will indicate any changes in the machine and signal potential issues that can be addressed in a timely manner. From this collected data, periodic testing can take place and the information can then be trended to provide a clear image of the machine’s health over a period of time. There are also strategies that equipment owners can implement without testing, which can drastically contribute to their machines’ health, such as storing motors in a clean and dry environment to avoid damage from moisture and pollutants. When electric motors work at optimal levels and are used as part of a circular economy model based on repairing and reusing, their sustainability can be massively improved. Chris Measor, Winding Assistant Manager at electro-mechanical specialist Houghton International explains how preventative maintenance can improve the sustainability of electric motors.