Improving the energy efficiency ratings of electric motors is a worldwide goal, but exemptions in the regulations mean that for applications in potentially explosive atmospheres there is no obligation to implement the latest technology. However, for one oleochemical processing company improving energy efficiency is an important objective, which led it to consult with Bauer Gear Motor when a number of ATEX motors needed to be replaced.
The manufacturing processes involved in the production of oleochemicals are analogous to those in the petrochemical industry; often involving potentially explosive atmospheres which require specialist equipment to ensure safe operation. The level of additional protection required is determined by the classification of the area in which the equipment is operating.
In this particular case, the application involved a number of mixing vessels that were located in a Zone 1 atmosphere and powered by explosion-proof gear motors. The company needed to replace the gear motors with new equipment of a similar specification but with improved energy efficiency and the ability to operate via inverter control.
The application engineers at Bauer assessed the requirements of the equipment and designed a drivetrain that consisted of an inverter duty IE4, ATEX rated permanent magnet synchronous motor (PMSM), coupled to a BG70 gearbox and controlled via a Danfoss FC-302 inverter. This combination provided the necessary control with the all-important energy efficiency while meeting the required increased safety levels.
Markus Kutny, Product Manager, Energy Efficiency Solutions at Bauer Gear Motor, explains the concept behind the design: “In today’s market energy efficiency has to be one of the key determining factors when specifying geared motor solutions. Energy prices are only going to go one way so it is important that a drive’s lifelong running costs are considered; rather than simply the cost of procurement. We have developed the new motor range in anticipation of the new IE4 classification and to offer our customers the very best in terms of efficiency.
“It is well known that electrical motors use 65% of the energy used in industry, but a lesser known fact is that 96% of the lifetime costs of an electric motor is associated with the energy consumption. This shows the importance of the overall efficiency compared to the initial purchase cost in the terms of the total cost of ownership (TCO).
“The design of modern drivetrains requires specialist knowledge and expertise in order to produce a product which will deliver efficiency, smoothness and low noise qualities as well as excellent reliability. However, further benefits of a good design can be gained by ensuring the drivetrain is properly integrated into the application.”
The original asynchronous motors (ASM) installed in the oleochemical process were designated as Ex d (explosion proof) and suitable for operation in zone 1. A detailed survey by Bauer engineers concluded that the new equipment could be rated to Ex e (increased safety) while still meeting the necessary requirements of zone 1 operation.
The final proposal submitted to the chemical processor showed significant savings in the initial purchase price of the gear motors as well as greatly reduced running costs. All of this, coupled with the experience of the Bauer engineers to complete the build and installation of the new equipment, was more than sufficient to sign the deal.
Ultimately, Bauer gear motors offers a high quality, well-engineered and above all reliable and efficient solution; with responsive engineering capabilities, prototyping and delivery times as well as an extensive global sales and service network, which provides local contacts and support wherever in the world the final application is located.
The design and manufacture of explosion-proof motors often results in the overall size and weight of the motor increasing. Bauer’s design and engineering has incorporated energy saving technology as well as the additional requisite protection while minimising the overall footprint of the motor.
Comparing the frame sizes of similarly rated IE3 ASMs to Bauer’s PMSMs up to the 11 kW model shows that the Bauer models are either equal to, or one frame size smaller than, the equivalent ASM. This optimises the integration possibilities for this range of motors as well as assuring increased power and torque compared to a motor of the same frame size.
The proposed solution was based around the PMSM series, which is an environmentally-friendly range of motors, employing a highly efficient rotor design that integrates embedded permanent magnets made from rare-earth metals, in place of a squirrel-cage rotor found in most low voltage induction motors.
The design of the PMSM offers a number of key benefits. It reduces heat losses from the rotor by 100%, total losses by approximately 25%, and increases total efficiency by 10% or more compared to the most efficient conventional motors. For the PMSM user, this improved performance translates into lower total cost of ownership, a reduction in CO2 emissions and on-going savings that buffer against future increases in energy costs. This was coupled to the BG series of helical geared motors which were chosen as they offer torque values of up to 18,500 Nm with high output speeds. The motors can be easily integrated with an inverter, such as the Danfoss FC-302 to ensure that the required speeds at each stage of the mixing process are maintained.
The gears are designed with ingress protection of up to IP66 and lubricant changes are only required after 15,000 operating hours, which is ideal for an application where reliability is key. These features also help to reduce the maintenance costs associated with the application.
In many cases, manufacturers of specialist motors such as these specify a particular inverter that has to be installed as part of the application. Bauer does not place any such restrictions on an application, preferring to allow the client to use an inverter that best suits the situation. This ensures that maintenance managers can optimise their spares inventory as well as avoiding the need for additional technical training on a new inverter.
Applications in explosion hazardous areas are currently exempt from the EU regulations on minimum energy efficiency because, clearly, explosion protection takes precedence over energy savings. This puts industries such as petrochemical, oil and gas and mining at a disadvantage when trying to improve overall site efficiency. As such Bauer has developed the world's first Ex rated IE4 PMSM geared motor, which offers the same levels of energy efficiency as the rest of its range as well as ATEX classification for Zones 1 and 21.