DAC February 2022

40 n HAZARDOUS AREAS February 2022 www.drivesncontrols.com Maintaining motors for use in hazardous areas I n 1834, the Prussian engineer Moritz Jacobi invented the first rotating electric motors that successfully generated mechanical output power. After four more years of work, he created a motor that could propel a boat with 14 people onboard across a wide river. Today, 180 years later, electric motors can be found almost everywhere, from the vacuum cleaners and dishwashers, to fans and pumps. A variety of motors have been designed to work in hazardous locations or harsh environment such as chemical plants, pulp and paper mills and foundries. In such conditions, maintaining the motors can be a challenge. Contaminants Motors operating in hazardous areas can be exposed to damaging pollutants and contaminants including excessive moisture, electrically conductive dust, chemical fumes, explosive gases and more. An enclosure can protect the working components of the motor. There are many types of enclosure, offering different levels of protection and cooling. Those typically used for hazardous area and heavy-duty motors include explosion-proof (XP), dust-ignition-proof and totally enclosed fan-cooled (TEFC) enclosures. XP enclosures are designed to contain an internal explosion of a specified hazardous substance inside the motor without igniting flammable gases or particles surrounding the motor. Maintaining XP enclosures can pose several challenges. Because they are installed in corrosive atmospheres, materials such as stainless-steel or bronze need to be used. The motors’ cable entries also require specific arrangements such as reductions, cable clamps and conduits. The use of these materials and components can result in high maintenance costs. The safety performance of XP enclosures depends on their proper maintenance. Motors with TEFC enclosures have exterior surfaces that are cooled by an external fan mounted on the motor shaft. They are used widely in dusty, dirty and corrosive atmospheres. In terms of maintenance, the motor needs to be kept clean to minimise heat transfer. Also, the internal temperature of the motor always needs to be kept higher than the surrounding environment to prevent condensation from forming inside the motor, which could corrode the windings. Overheating A key reason for motors failing is overheating. Particularly for motors operating in areas that experience extreme temperatures, excessive heat can deteriorate both the winding insultation and the bearings. Moreover, contamination from dust and debris and high levels of vibration can increase the internal temperature of a motor to an unsafe level. Additionally, motors running at higher altitudes might be more likely to suffer from overheating, because the reduced air pressure and density in these locations results in larger temperature swings. To avoid these issues, thorough and regular maintenance is needed. Manufacturers can install smart sensors to detect a motor’s temperature in real time and receive an alert before it reaches a dangerous level. Since the lack of ventilation is also a problem, users need to ensure that the motor’s ventilation holes are clear, and that fans are working properly. In liquid- cooled motors, it’s important to monitor coolant levels regularly and to top them up when necessary. According to the new EU ecodesign regulation, motors for special purposes with ratings from 0.75kW to 1MW must achieve an efficiency level of at least IE3. The new directives don’t mean that manufacturers in the EU need to replace their existing motors, but that all the new hazardous area motors they buy from now on must be rated at IE3 or higher. Malfunctions of motors operating in harsh conditions can be frustrating, because they cause unexpected hazards and downtime, which can adversely affect a business’ bottom line. Fortunately there are a variety of electric motors available to suit all types of harsh conditions. n To keep motors reliable and efficient, well-planned maintenance is essential, especially when operating in hazardous areas. Neil Ballinger, head of EMEA at automation parts supplier EU Automation, discusses the maintenance challenges of motors used in harsh environments. Hazardous environments such as offshore oil and gas production platforms require specialised electric motors that need to be carefully maintained