ABB has announced a range of large Nema-frame AC motors for hazardous area applications which, it says, deliver an average of 15% more power than conventional designs. The AXR 5000 and 5800 motors meet American Petroleum Institute 541 and 547 standards for motors used in the oil and gas industry.

The motors are said to achieve higher power/weight ratios than conventional TEFC (totally-enclosed, fan-cooled) motors, with smaller frame sizes in some power ratings. This can reduce their overall length by up to 8 inches (20cm), saving space on oil platforms and in refineries.

The new motors also offer improved cooling, helping to extend their lives. An internal cooling loop circulates air inside the motor, moving heat to the frame. An external fan blows air over the frame to remove the heat.

“The new cooling configuration offers a more thermally equalised motor, eliminating hot spots that have been seen in TEFC motors,” says Charles Blankenship, ABB’s product manager for large AC motors. “Better cooling reduces the thermal stresses on the insulation system, which helps improve the motor’s longevity.”

The main terminal boxes and auxiliary boxes can be mounted in several positions, simplifying installation and maintenance. This also means fewer spares are needed. The rigid frame increases stability so that the motor meets stringent API vibration limit specifications.

The new motors have sleeve bearings that operate at lower temperatures, last longer and are easy to maintain. The motors are available in ratings up to IP56, providing protection against contamination and dust ingress.