Drives and Controls Magazine
High-inertia motors have longer stall than start times
Published:  26 July, 2013

ABB has announced a range of high-power motors designed to accelerate high-inertia loads, such as axial fans. With standard motors, the long start times of such loads can lead to overheating. The new motors have been designed to withstand the increased temperature rise during start and stall conditions, and have stall times longer than their start times.

“Our new high-inertia motors are based on our well-established modular induction motor, so customers can be confident they are getting robust, reliable motors,” says Karita Forss of ABB’s high voltage induction motor product management. “We adapted the platform by optimising the rotor bar composition, and dimensioning and overall design for high-inertia loads.

“The rotor bars are made from carefully selected materials, including higher-resistivity copper alloys,” she explains. “The motors have been re-dimensioned to accommodate the temperature rise associated with high-inertia starts, and the overall design has been optimised to achieve the optimum balance between torque and temperature performance with high-inertia loads.”

The 6–10 pole Nema-standard motors cover the power range 7,000–18,500hp (5.2–13.8MW) in frame sizes 710–900, and can be supplied for power supplies up to 13.2kV, 60Hz. There is a choice of cooling systems.

ABB's high-inertia motors can be used to drive large fans

Users can choose between motors with higher or lower stall requirements, depending on their application. The higher-stall versions have a “hot” stall time at least five seconds longer than the start time at voltage levels from 80–100% of nominal. Motors meeting the lower stall requirements have a “cold” stall time that exceeds the start time at all voltage levels from 80–100% of nominal.