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Three Phase Electric Motors – Electric Motors Guide & Range

An in-depth guide to three phase motors for industry. How they work, types, applications & how to choose – plus our stocked ranges and IE3 & IE4 options.

Aluminium IE3 Motors

Aluminium IE3 Motors

Lightweight IE3 three phase motors for general industrial use. Ideal for extractor fans, compressors, conveyors, and packaging Machinery. 0.09kW (0.12hp) to 22kW (30hp) from stock.

Cast Iron IE3 & IE4 Motors

Cast Iron IE3 & IE4 Motors

Robust and rugged IE3 & IE4 three phase motors for harsh environments. Ideal for crushers, mixers and quarry machinery. Available from 0.75kW (1hp) to 355kW (470hp) from stock.

Hazardous Area Motors

Hazardous Area Motors

ATEX-certified flameproof motors for Zone 1 & 21 hazardous locations in oil, gas, chemical and pharmaceutical industries. 0.75kW (1hp) to 18.5kW (25hp) from stock.

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What is a Three Phase Motor?

A three phase electric motor uses three AC waveforms that are 120° out of phase with each other, compared to single phase AC motors which operate on a single alternating waveform. This creates a continuous rotating magnetic field in the stator, which produces a smooth, constant torque output. Three phase motors require a three-phase power supply (typically 400V).

Due to the design, three phase motors:

  • Start without the need of capacitors or auxiliary windings thus making them more reliable during start up.
  • Run more efficiently compared to single phase motors, with the current highest single phase motor efficiency at IE2 (which we stock!), and three phase motors now able to achieve IE3 & IE4 saving you on energy costs.
  • Deliver high power in a more compact frame size. We also stock the increased output three phase motors.
  • Are better suited to continuous duty work as well as frequent start/stop applications.

At MM Engineering, we stock a comprehensive range of three phase motors from 0.09kW (0.12hp) to 355kW (470hp) in both 230V/400V and 400/690V configurations. Our motors are IE3 & IE4 efficiency design, have metal terminal boxes, manufactured to IEC standards, and supplied with a 12-month warranty. Another benefit our motors have over others is they all have a PTC Thermistors as standard and our Aluminium range have multi-mount feet allowing you to have the terminal boxes positioned on top, left or right hand side. With same day despatch, FREE next day delivery on UK mainland orders and expert technical support, we make buying the right three phase motor simple.

Three Phase Motor Types Compared

Choosing the right type of three phase motor depends on your area classification requirements and application.

Aluminium IE3 Safe Area Motors

  • Best For - Lightweight general industrial use
  • Voltage - 230/400V or 400/690V
  • Applications: Fans, Pumps, Conveyors
  • Key Benefit: High resistance to corrosion, lightweight and multi-mount design.
  • Power Range: 0.09kW (0.12hp) - 22kW (30hp)

    • View Catalogue

    Cast Iron IE3 & IE4 Safe Area Motors

  • Best For - Robust and rugged harsh environments
  • Voltage - 230/400V or 400/690V
  • Applications: Crushers, Mixers, Quarries/Mining
  • Key Benefit: Superior vibration damping & durability
  • Power Range: 0.75kW (1hp) - 355kW (470hp)

    • View Catalogue

    Brake Motors

  • Best For - Lightweight general industrial use with a braking requirement.
  • Voltage - 230/400V or 400/690V
  • Applications: Circular Saws, Conveyors, Elevators
  • Key Benefit: High resistance to corrosion, lightweight and multi-mount design.
  • Power Range: 0.18kW (0.25hp) - 15kW (20hp)

    • View Catalogue

    Hazardous Area Motors

  • Best For - Explosive environments with flammable gases/combustible dust.
  • Voltage - 230/400V or 400/690V
  • Applications: Fans, Pumps, Conveyors
  • Key Benefit: High resistance to corrosion, lightweight and multi-mount design.
  • Power Range: 0.12kW (0.16hp) - 18.5kW (25hp)

    • Aluminium IE3 Three Phase Motors

    Aluminium IE3 three phase motors are engineered for general industrial applications where reliability, low weight and cost efficiency is important.

    An aluminium frame construction keeps the weight low, making installation simpler than heavy Cast Iron alternatives. A Multi-mount design allowing the terminal box to be positioned top, left or right hand side on the stator frame allows flexible installation into the tightest of spaces. The aluminium frame is also corrosion resistant which proves to be a real benefit in damp environments.

    Ideal Applications

    • Centrifugal Pumps
    • Air compressors and refrigeration compressors
    • Conveyors and material handling
    • Woodworking machinery (saws, planers, thicknessers)
    • Gearbox-driven equipment
    • Industrial fans and blowers
    • Car lifts/car ramps

    We stock Aluminium IE3 three phase motors from 0.09kW (0.12hp) to 22kW (30hp) in 2-pole (3000rpm), 4-pole (1500rpm), 6-pole (1000rpm) and 8-pole (750rpm) configurations. All motors feature high-quality aluminium construction, NSK bearings, IE3 design, complete with 3×PTC Thermistors for added protection and multi-mount design.

    Our most popular Aluminium IE3 Three Phase Motors

    IE2 Efficiency
    Amtecs 0.12kW (0.16HP) Three Phase Motor 4-Pole (1500 rpm) 63 Frame
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    Amtecs 0.12kW (0.16HP) Three Phase Motor 4-Pole (1500 rpm) 63 Frame

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    Amtecs 0.12kW (0.16HP) Three Phase Motor 4-Pole (1500 rpm) 63 Frame
    £105.01Inc VAT £87.51 Ex VAT
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    Cast Iron IE3 & IE4 Three Phase Motors

    Cast Iron IE3 & IE4 three phase motors for rough and rugged applications where durability and low vibration is an important factor when selecting the correct construction type for an application.

    An cast iron frame motor uses its heavier construction to absorb vibration, handle shock loads to operate reliably in harsh conditions.

    Ideal Applications

    • Large Centrifugal Pumps
    • Industrial compressors
    • Heavy-Duty Conveyors and material handling
    • Mining & Quarrying machinery
    • Gearbox-driven equipment
    • Crushers, Grinders and milling equipment
    • Other high vibration applications

    We stock Cast Iron IE3 & IE4 three phase motors from 0.75kW (1hp) to 355kW (470hp) in 2-pole (3000rpm), 4-pole (1500rpm), 6-pole (1000rpm) and 8-pole (750rpm) configurations. All motors feature high-quality aluminium construction, NSK bearings, IE3 & IE4 design, complete with 3×PTC Thermistors for added protection and solid cast feet.

    Our most popular Cast Iron IE3 & IE4 Three Phase Motors

    IE2 Efficiency
    Amtecs 0.12kW (0.16HP) Three Phase Motor 4-Pole (1500 rpm) 63 Frame
    View Details

    Amtecs 0.12kW (0.16HP) Three Phase Motor 4-Pole (1500 rpm) 63 Frame

    amtecs
    IN STOCK

    Amtecs 0.12kW (0.16HP) Three Phase Motor 4-Pole (1500 rpm) 63 Frame
    £105.01Inc VAT £87.51 Ex VAT
    View Details
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    Three Phase Motor Speed (RPM) Ratings

    Our three phase motors are available in various speeds, ranging from 750RPM to 3000RPM, covering virtually all domestic, commercial and light industrial applications.

    Speed Options

    Single phase motors are available in three standard speeds:

    • 2-Pole (3000 RPM) – Higher speed, suitable for direct-drive applications like circular saws, pumps, and machinery requiring high rotational speed but have lower torque than a 1500rpm.
    • 4-Pole (1500 RPM) – Lower speed with higher torque, ideal for car lifts, gearbox-driven equipment, conveyors, and applications requiring more turning force.
    • 6-Pole (1000RPM) – Some applications also use 6-pole (1000 RPM) motors for higher torque at slower speeds such as industrial mixers and conveyors.
    • 8-Pole (750RPM) – Some applications also use 8-pole (750 RPM) motors for maximum torque requirements such as slow running material handling applications - hoists, cranes and elevators where a controlled movement is important.

    Three Phase vs Single Phase Motors – Key Differences

    Both designs have their place, but for industrial duty three phase motors offer clear advantages in performance, efficiency and lifetime cost.

    • Features Three Phase Motor Single Phase Motor
    • Power range 0.09kW (0.12hp) – 400kW+ (540hp+) 0.09kW (0.12hp) - 3.7kW (5hp)
    • Efficiency IE3 (Premium Efficiency)/ IE4 (Super Premium Efficiency) IE2 (High Efficiency)
    • Torque Smooth, constant Pulsating, needs start & run capacitors
    • Starting Self-starting Needs start/run capacitor
    • Best for Industrial machinery, pumps, fans, compressors Domestic (240V) or light-duty equipment

    Three Phase Motor Frame Sizes Explained

    Electric motors come in various frame sizes which determines the physical dimensions of the motor, including the mounting hole positions, shaft height, shaft diameter, length and keyway details. It is essential to match the frame size when replacing an existing motor.

    Common Frame Sizes

    • Frame Shaft Height Typical kW Range
    • 56 56 mm 0.09kW (0.12hp) - 0.12kW (0.16hp)
    • 63 63 mm 0.12kW (0.18hp) - 0.18kW (0.25hp)
    • 71 71 mm 0.25kW (0.33hp) - 0.55kW (0.75hp)
    • 80 80 mm 0.55kW (0.75hp) - 1.1kW (1.5hp)
    • 90 90 mm 1.1kW (1.5hp) - 2.2kW (3hp)
    • 100 100 mm 2.2kW (3hp) - 3.0kW (4.0hp)
    • 112 112 mm 3.7kW (5hp) - 4.0kW (5hp)
    • 132 132mm 5.5kW (7.5hp) - 7.5kW (10hp)
    • 160 160mm 11.0kW (15hp) - 15.0kW (20hp)
    • 180 180mm 18.5kW (25hp) - 22.0kW (30hp)
    • 200 200mm 30.0kW (40hp) - 37.0kW (50hp)
    • 225 225mm 45.0kW (60hp)
    • 250 250mm 55.0kW (75hp)
    • 280 280mm 75.0kW (100hp) - 90kW (125hp)
    • 315 315mm 110 (150hp) - 132kW (180hp)
    • 355 355mm 250kW (420hp) - 315kW (420hp)

    Three Phase Motor Mounting Options

    All our three phase motors feature multi-mount design with removable feet, allowing flexible installation. Standard mounting options include:

    B3 (Foot mounted)

    The most common configuration, where the feet are bolted to a base/mounting plate.

    B5 (D Flange mounted)

    Large flange for mounting direct to equipment. No feet required.

    B14 or B14S (Small C Face mounted)

    Smaller face flange for compact installation with drilled and tapped holes.

    B14L (Large C Face mounted)

    Larger face flange for compact installation with drilled and tapped holes.

    B34S (Foot & Small C Face mounted)

    A combination of a foot mount and a small face mount for a secure fit with maximum flexibility.

    B34L (Foot & Large C Face mounted)

    A combination of a foot mount and a large face mount for a secure fit with maximum flexibility.

    B35 (Foot & D Flange mounted)

    Combination mounting with large flange providing both stability on the ground and a direct flange coupling to the driven equipment.

    V1 (Vertical Flange mounted with Rain canopy)

    Large flange for direct mounting in a vertical position to equipment. No feet required with added protective rain canopy that shields the top of the motor from water ingress, dirt, and debris.

    How to wire a Three Phase Motor

    Three phase motors have a terminal box with clearly marked connections. Typically: U1, U2, V1, V2, W1 and W2. Motors are generally wired to rotate in a clockwise direction (viewed from the Drive End (shaft end)) when the phase L1, L2 and L3 are connected to the connections U1, V1 and W1. To change the direction of rotation you simply swap any two phase lines e.g. swap L1 and L2.

    Three Phase Motor Applications

    Three phase motors power equipment across numerous industries and applications:

    Pumps & Water Treatment

    • WIMES Spec Pump Motors • Borehole pumps • Pressure boosters • Swimming pool pumps • Pond pumps • Heating circulation pumps

    Fans, HVAC & Air Handling

    HVAC & Ventilation • Extractor fans • Air handling units • Workshop dust extractor fan

    Manufacturing & Machine Tools

    • Circular Saws • Band Saws • Pillar Drill • Planer Thicknesser

    Crushers & Mining Machinery

    • Electric Rock Crusher • Quarry conveyor belts

    How to Select the Right Three Phase Motor

    Selecting the right three phase motor for your application requires matching several key specifications:

    • Specification Description
    • Power Rating Match or slightly exceed the power (W/kW/hp) requirement of your application. Check the existing motor nameplate or equipment manual.
    • Speed (Poles) 2-pole (3000 RPM) for high-speed applications. 4-pole (1500 RPM) for higher torque applications, 6-pole (1000 RPM) for slow and high torque or 8-pole (750 RPM) for maximum torque.
    • Frame Size Measure the existing motor frame size to ensure correct mounting dimensions and shaft height.
    • Motor Type Aluminium, Cast Iron, Brake Motor, Hazardous Area
    • Voltage 230/400V or 400/690V
    • Mounting Type B3 foot, B5 flange, B14 face, or combination mounting (B34 foot & face or B35 foot & flange)

    Three Phase vs. Single Phase Electric Motors:Quick Comparison

    Not sure on one or more of the steps above? Use our Motor Selection Wizard or contact our technical team and we'll recommend a suitable three phase motor for your application.

    • Feature Three Phase Motor 400V Single Phase Motor 230V
    • Voltage (UK) 400V 230V/240V
    • Wiring Connections L1 + L2 + L3 (+ Earth) Live + Neutral (+ Earth)
    • Starting Method Self-starting Capacitors + Centrifugal Switch
    • Max Power Limit Almost Unlimited (up to High Voltage) 3.7kW (5HP)
    • Efficiency High Efficiency (IE3/IE4/IE5) Standard - IE1 & IE2
    • Starting Torque High Medium
    • Full Load Torque High Medium
    • Variable Speed Control Suitable for Speed control Not suitable for speed control
    • Cost Lower Higher
    • Typical Use Factories, Large Industrial/Manufacturing sites Home, Domestic, Small workshops

    Three Phase vs. Single Phase Electric Motors:Real World Example (0.75kW/1hp)

    See below the actual difference between a 0.75kW (1hp) three phase motor vs a 0.75kW (1hp) single phase motor.

    • Frame Three Phase Motor 400V Single Phase Motor 230V
    • Voltage (UK) 400V 230V/240V
    • Power 0.75kW (1hp) 0.75kW (1hp)
    • Speed (RPM) Approx. 1400rpm Approx. 1400rpm
    • Frame Size 80 (80mm shaft height) 80 (80mm shaft height)
    • Wiring Connections L1 + L2 + L3 (+ Earth) Live + Neutral (+ Earth)
    • Starting Method DOL Starting 2 x Capacitors + Centrifugal Switch
    • Max number of start/stops 10 per hour 4-6 per hour
    • Efficiency IE3 - 82.5% IE2 - 79.6%
    • Starting Torque 14.88Nm 12.29Nm
    • Full Load Torque 4.96Nm 5.12Nm
    • Full Load Current 3.04A 4.4A
    • Cost £ 132.15 + VAT £ 144.71 + VAT
    • Availability In stock - FREE delivery to UK In stock - FREE delivery to UK

    Frequently asked questions
    What is a three phase electric motor?

    A three phase motor uses three alternating currents to deliver smooth, efficient industrial power.
    Where are three phase motors used?

    Three phase motors are commonly used in pumps, fans, compressors, conveyors, and process machinery.
    Why choose a three phase motor over a single phase motor?

    Three phase motors provide higher efficiency, smoother torque, better reliability, and improved performance for larger industrial loads.
    What three phase motor voltages are available?

    Typical supply voltages include 230/400V, 400/690V, and other IEC standard three phase voltages.
    What do 2 pole, 4 pole, and 6 pole mean?

    Motor poles determine operating speed:

    • 2 Pole ≈ 3000 RPM
    • 4 Pole ≈ 1500 RPM
    • 6 Pole ≈ 1000 RPM
      (at 50Hz supply frequency)
    How do I size a three phase motor?

    Motor sizing depends on the required kW, speed, duty cycle, starting method, and the driven load/application.
    What IP rating do three phase motors have?

    Standard industrial motors are typically rated IP55. Higher protection ratings such as IP65 and IP66 are available for harsh or demanding environments.
    Do you supply IE3 and IE4 efficiency three phase motors?

    Yes, IE3 premium efficiency and IE4 high efficiency three phase motors are available from stock.
    Can three phase motors be inverter driven?

    Yes, most modern three phase motors are compatible with VFD (Variable Frequency Drive) speed control.
    Do you offer ATEX rated three phase motors?

    Yes, ATEX certified three phase motors are available for hazardous and explosive environments.