In 1834, the Prussian engineer Moritz Jacobi innovated the first real rotating electric motors that successfully generated mechanical output power. After four years, he created another motor that could power a boat with 14 people on board across a wide river.
It may be hard to imagine that today, after one hundred and eighty years, electric motors can be found in almost everything, from the vacuum cleaners and dishwashers we use at home, to fans, pumps, blowers and turbines in manufacturing plants. A wide range of motors are designed and constructed to work in hazardous locations or harsh environment such as chemical plants, pulp and paper mills and foundries. In such conditions, the maintenance of electric motors can be very challenging.
Protection from contaminants
Motors operating in hazardous areas are highly exposed to damaging pollutants, including excessive moisture, electrically conductive dust, chemical fumes, explosive gases and more. To protect the working components of the motor, an enclosure can be used. There are many types of enclosures, each offering different levels of protection and cooling. The ones that are generally used for hazardous area motors and heavy-duty motors include explosion-proof (XP) enclosures, dust-ignition-proof enclosures 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. The maintenance of XP enclosures can present several challenges. Since these enclosures are used in corrosive atmospheres, materials including stainless steel or bronze need to be used. The cable entries also require a specific arrangement, which includes reductions, cable clamps, conduits and so on. The use of these particular materials and items may cause high maintenance costs. Furthermore, the safety level of XP enclosures highly depends on their proper maintenance by the plant personnel.
Motors with a TEFC enclosure have exterior surfaces that are cooled by an external fan on the motor shaft. They are widely adopted in dusty, dirty, and corrosive atmospheres. In terms of maintenance, it’s necessary to keep the motor 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 may corrode the windings.
One of the key reasons for motor’s breakdown is overheating. Particularly for motors operating in areas with extreme temperatures, excessive heat may seriously deteriorate both the winding insultation and the bearings. Moreover, contamination from dust and debris and high levels of vibration could 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 cause larger temperature swings.
To avoid these issues, thorough and regular maintenance is needed. Manufacturers could install smart sensors to detect a motor’s temperature in real time and receive an alert before the motor’s temperature reaches a dangerous threshold. Since the lack of ventilation is also a problem, manufacturers need to ensure that the ventilation holes are clear, and that fans are working properly. In liquid cooled motors, it’s important to regularly monitor coolant levels and to top up when necessary.
According to the new EU ecodesign regulation, from 1 July, motors for special purposes rated from 0.75kW to 1MW must reach 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 purchase from now on must be rated IE3 or higher.
The malfunctions of motors operating in harsh conditions are frustrating, as they cause unexpected hazards and downtime, which adversely affect businesses’ bottom lines. EU Automation offers a comprehensive supply of electric motors for operations in harsh conditions. For more information about our range of new, refurbished and obsolete electric motors, visit https://www.euautomation.com/uk/motors-encoders.