1120–1720kW 4-Pole 6kV IP55 Three-Phase High-Voltage Squirrel Cage Induction Motor – AMI 450L4A

The ABB AMI 450L4A is a medium-frame modular high-voltage squirrel-cage induction motor developed on ABB’s proven AMI product platform, with rated power coverage from 1120kW to 1720kW. Featuring a 4-pole configuration, it runs at a synchronous speed of 1500rpm, with a standard rated voltage of 6kV and 50Hz frequency. Designed and manufactured to comply with IEC and NEMA international standards, this welded steel-plate motor is built for S1 continuous heavy-duty operation. The standard configuration adopts IC611 air-to-air closed cooling and IP55 protection grade. Thanks to its modular mechanical design, cooling units, condition monitoring sensors and auxiliary assemblies can be flexibly configured to satisfy various demanding site requirements. It is widely deployed in thermal power, cement, mining, water conservancy and petrochemical industries to drive medium-speed heavy-duty equipment such as large centrifugal fans, circulating water pumps and process compressors.

Core Technical Parameters 

Electromagnetic performance is optimised by multi-working-point finite element simulation, specially tuned for the medium-speed load characteristics of 4-pole motors, adapting to long-term continuous operation and frequent partial-load cycles of fans and pumps. The stator core is stacked with premium low-loss silicon steel laminations to reduce iron loss, stray loss and magnetic leakage under both full-load and partial-load operating conditions. The stator winding uses high-grade corona-resistant magnet wire and undergoes complete VPI vacuum pressure impregnation treatment. The reinforced winding-end structure enhances mechanical rigidity, dielectric strength and resistance to electrical ageing, enabling the motor to withstand industrial grid voltage fluctuations and impact loads generated during repeated startup. The rotor adopts a heavy-duty copper-bar squirrel cage structure, delivering excellent mechanical stability, low rotor losses and consistent starting performance. Each rotor assembly is processed with multi-stage high-precision dynamic balancing to control vibration and noise strictly within IEC allowable limits for long-term medium-speed continuous service.

The welded modular steel-plate frame is a signature advantage of the ABB AMI series, supporting flexible matching of cooling systems and auxiliary accessories according to on-site environmental conditions. The AMI 450L4A is normally fitted with the IC611 air-to-air closed cooling system. Two independent air circuits are arranged inside the motor: internal hot air circulates in the sealed frame and transfers heat to external ambient air via the top-mounted air-to-air heat exchanger. The IP55 enclosure provides reliable protection against dust ingress and water splash, making the motor suitable for humid and dusty industrial sites where open-ventilated motors cannot operate steadily. For locations with poor ambient air quality or insufficient heat dissipation capacity, the IC81W air-to-water cooling option can be selected to improve heat exchange efficiency.

The bearing system is customised for 4-pole medium-speed heavy-load continuous working scenarios. Heavy-duty rolling bearings are standard for this frame size, while sliding bearings can be supplied for the upper power range or applications with notable impact and vibration loads. PT100 temperature sensors can be factory-preinstalled in stator windings and bearing housings, transmitting real-time temperature data to the plant DCS system for remote condition monitoring and overtemperature protection. Space heaters are available as an option to prevent winding condensation when the motor stays on standby. For variable-frequency energy-saving retrofit projects, an IC616 cooling variant can be provided to guarantee adequate cooling airflow during low-speed variable-frequency operation. Customisable options include ATEX explosion-proof modification, high-altitude adaptation, tropical anti-humidity and anti-corrosion coating, special terminal box layout and double shaft extension to meet complex project specifications.

Typical driven machinery includes large centrifugal induced draft fans, circulating water pumps, process compressors and medium-flow centrifugal pumps. The motor supports direct-on-line starting or high-voltage soft starter starting, subject to the short-circuit capacity of the on-site power grid. Before shipment, every motor undergoes comprehensive factory acceptance tests, including insulation resistance test, power-frequency withstand voltage test, no-load running test, efficiency verification, vibration and noise measurement. Built on ABB’s mature AMI modular platform, AMI 450L4A delivers stable and dependable operation, convenient spare parts interchangeability and low life-cycle cost for critical medium-speed heavy-duty industrial applications.