Did you know that today’s induction motors were first patented by Nicola Tesla in 1887? Over the last 130+ years, they have become integral to our everyday lives. For example, you’ll find a small induction motor powering most pumps, food service equipment, and even your air conditioning unit. But you’ll also find an induction motor powering larger industrial machines, such as hoists, crushers, and oil extraction mills.
With such a wide variety of sizes, you’re probably wondering if an induction motor suits your business or industry. So, let’s start with a quick review of induction motor components and what they do.
Induction Motor Components
No matter the size or application, every induction motor has the same essential components.
- Case or housing
- Stator
- Rotor
- Bearings
Like a building, the induction motor housing protects the internal components from exposure to the elements. Most cases feature an electrical connection box and exterior cooling fins or vents to dissipate the heat generated during operation. Induction motors also utilize a frame, mounting plate, or tabs to attach to other machinery or a concrete slab. Induction motor housings are available in the following configurations.
- Open Motor
- Open Drip-proof Motor (ODP)
- Screen Protected Drip Proof Motor (SPDP)
- Drip-Proof Fully Guarded Motor (DPFG)
- Splash-proof Motor
- Totally Enclosed Motor
- Totally Enclosed Non-Ventilated (TENV) Motor:
- Totally Enclosed Fan-Cooled (TEFC) Motor
- Totally Enclosed Blower-Cooled (TEBC) Motor:
- Encapsulated Motor
- Totally Enclosed Explosion Proof (TEXP) Motor
The stator uses electromagnets made from slotted steel or layers of iron “stacked” upon each other to create a cylinder around the rotor. Once formed, copper wire is wound in alternating directions throughout the cylinder to create magnetic poles. As the AC current travels through the windings, the directional flux causes the polarity to move back and forth with each half-cycle. This process creates an alternating magnetic field that “induces” the rotor to turn.
The rotor contains a second set of electromagnets arranged to create another cylindrical shape. This rotor is mounted to an axle assembly that allows it to spin within the stator. The fields induced within the rotor are naturally attracted to the stator’s magnetic field as it rotates with each half-cycle of alternating current.
Bearings at each end of the rotor shaft allow the rotor to spin freely at different speeds and loads. Properly maintained bearings reduce rolling friction, improving operating efficiency and extending the motor’s life cycle.
Single Phase Induction Motors
While not suitable for heavy-duty industrial applications, single-phase induction motors are found in pumps, fans, household appliances, and compressors. There are four specific types of single-phase induction motors.
- Split Phase – utilizes split-phase wiring to provide moderate starting torque.
- Capacitor-Start – incorporate a capacitor to increase the starting torque.
- Capacitor-Run – feature a capacitor in the running circuit to improve efficiency.
- Capacitor Start Capacitor Run – include capacitors on the start and run circuits for maximum efficiency.
- Shared Pole – this simple and reliable design is ideal for small appliances.
Three-Phase Induction Motors
Three-phase induction motors are available in two different configurations.
Squirrel Cage—Due to their simple design and improved reliability, squirrel cage motors are ideal for various industrial applications, such as conveyors, compressors, and pumps.
Slip Ring/Wound Rotor – these motors provide superior control over speed and starting torques, making them ideal for elevators and cranes.
Induction Motor Efficiency
The conversion of electrical energy to mechanical work is typically referred to as motor efficiency. The higher the efficiency rating, the easier it is for the motor to deliver the desired mechanical output. The International Electrotechnical Commission (IEC) has established the following efficiency classes.
IE1 includes Standard Efficiency level motors
IE2 for High-Efficiency level motors
IE3 covers Premium Efficiency rated motors
IE4 includes Super Premium Efficiency rated motors
IE5 for all motors rated Ultra-Premium Efficiency
Using a high-efficiency motor reduces energy usage, delivers cost savings across the motor’s lifecycle, and lowers local environmental impact.
Electric induction motors can power your business in many ways, from small fans to massive machines. Therefore, choosing the best vendor and service team is paramount to selecting the best induction motor for your specific business needs.
With over 75 years of experience keeping our customers up and running, the Hi-Speed team is ready to answer all your questions about electric induction motors, from choosing the best motor to routine maintenance needs. You can email the Hi-Speed Electric Motor Experts or call us at 800-713-0103 to learn more about electric induction motors or any other services we provide, including electric motor rewinds or regular maintenance contracts to reduce emergency repairs.