Electric Motors 3 Phase
3 Phase Electric Motors
What is a 3 Phase Motor?
A 3 Phase Motor is an induction motor or asynchronous motor. In these motors, the electric current in the rotor is supplied by 3 separate phases, this then produces torque by means of electromagnetic induction from the stator winding. Induction motors are available in two types, the squirrel cage motor or the wound type.
At ACDC we supply the squirrel cage type motors due to their compatibility with Inverters and the compact size and reliability. Historically, these types of motors would have been used in a single-speed application, varying the number of poles to enable an element of speed control or selection, but with VFD's now becoming far more affordable and their cost savings becoming widely recognised, these motors are now used more and more in variable speed applications.
An estimated 30-40% of all newly installed asynchronous motors now include a VFD to control the speed or to offer enhanced functionality or cost savings on energy.
Aluminium or Cast Iron Framed Motor?
Aluminium 3 Phase Motors
Aluminium 3 Ph Motors offer a great compromise between weight and efficiency. They are perfectly suited to industrial use and in the smaller frame sizes are more frequently used than cast iron. An Aluminium frame motor will often weigh up to 30% less than its equivalent cast-iron motor although dimensionally the same. We offer Aluminium motors in 3 phase between 0.75kW and 37kW up to frame size 200.
Our Aluminium motors all feature sealed for life bearings. The fan and covers (cowls are independent and can be replaced if damaged or even swapped out for a Force Vent Unit if the motor will be used at low speeds for prolonged periods.
Our aluminium ranges feature Cast Feet, which can be bolted in different locations on the motor body to allow the motor in effect to be 'rotated', allowing for greater flexibility when mounting the motor. This also changes the position of the terminal box so it can be located on either side of the motor, again maybe saving space or making the location of the terminals easier to reach for servicing.
Aluminium motors due to the nature of the material also offer better resistance to corrosion in areas where the air or atmosphere is damp or contains corrosive particles.Aluminium Motors can often be found in these applications:
- Water Treatment / Sewage Plants
- HVAC Systems
- Food and Drink Manufacturing
- Conveyor systems
Cast Iron 3 Phase Motors
Cast Iron Motors are identical in size, but obviously, due to the nature of the material they are made from, weigh considerably more. Although this can be negative, there are a lot of beneficial aspects of this material; due to the material being stronger, the bearing seats will be better suited to larger loads, including side loads such as those exerted when using pulleys or belts, the cast iron also aids inductance, which is why the IE3 motors are usually only available with Cast iron frames.
Due to the costs of production, the prices of Cast iron start to become more competitive in the mid ranges of 11kW and above.
Our range of Cast Iron Motors are available from 0.75kW up to 355kWCast Iron 3Ph Motors can often be found in these applications:
- Large Fans
- High powered pumps
- Scrap metal Plants
- Heavy Industry
|Aluminium 3 Phase Motors||Cast Iron 3 Phase Motors|
|kW Ratings||0.75kW - 37kW||0.75kW - 315kW|
|Frame Sizes||80 - 200||80 - 355|
|Suitable For Corrosive Environments|
|Available in IE2 Efficiency|
|Available in IE3 Efficiency|
|Multi-Mount||Moveable Feet||Moveable Feet|
|Frequency||50 / 60 Hz||50 / 60 Hz|
Can I Use 3 Phase Motors With An Inverter?
All motors in our range are inverter compatible and include the appropriate ratings on the name-plate on the side of the motor.
Slow Running For Prolonged Periods With An Inverter?
Please note that if the motor will be used to run at low speeds with an inverter for periods longer than a few seconds, the standard fan will not provide enough flow and you will require a Forced Vent Unit which will run off a separate supply and supply sufficient air to cool the motor.
This is due to the fact that a standard fan runs off the rotor and therefore operates at the same speed as the motor at any given time. If the motor is turning at 100rpm but under high load for example, then the fan will not be supplying enough airflow over the cooling fins to sufficiently cool the motor. The forced ventilation unit replaces the standard fan and is powered by a separate supply, maintaining airflow and cooling.
What Determines The Speed Of My Motor?
A motors base speed (or maximum RPM) is usually determined by the number of poles it has. The fewer the number of poles, the higher the maximum speed; inversely with more poles, the speed decreases, but the torque produced by the motor increases. The table below is a rough guide to the base speeds, these vary due to efficiency differences and are only nominal figures.
|Number of Poles|
If the Output speed you require from your motor doesn't match the ones in the chart above, don't worry. By using either an Inverter or a Motor Gearbox, we can give you a solution for almost any speed you may require. By adding a gearbox, you will also significantly increase the final torque output from your motor. See our Gearbox section for more details.
How Configuring Your Motor For Use in Star Or Delta
If you are using a 3 Phase motor with an inverter with an input of 230VAC, you will need to ensure the motor is configured with its windings in a Delta arrangement. If you require help in doing this, please use the videos below.
Motor in Star Configuration
If you need guidance in checking which way your motor is currently configured, then please watch our useful tutorial on configuring your 3 phase motor in Star here:
Motor in Delta Configuration
If you need guidance in checking which way your motor is currently configured, then please watch our useful tutorial on configuring your 3 phase motor in Delta here:
Why Buy 3 Phase Motors from ACDC Drives?
We use these motors every day, so if you have any questions, just ask! We all know that in the modern workplace often things are needed as fast as possible. That is where we can help. We can also get engineers out to the site, to carry out surveys, or to install and commission motors on existing or new applications. Call our sales team today by phone on 01905 887 667.