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A typical 2 speed three phase motor will have 6 leads on the motor windings which will require 3 contactors to incorperate both the "high" and the "low" speeps.

Inorder for the motor to run on "low" speed you need to have a contactor (c1) that pulls in for the L1, L2,L3 leads... that should achieve the "low" speed of the motor..

To achieve the "high" speed you will need a contactor (c2) to shun or short L1,L2,L3 together... and another contactor (c3) to pull in the L4,L5,L6 leads...

to recap ... Low speed will requrie c1= L1,L2,L3 powered by phase 1, phase 2, phase 3 of the primary source voltage.

High speed requires c2 to short or shun L1,L2,L3 together while c3= L4,L5,L6 to be powered by Phase 1, Phase 2, Phase 3 fo the primary source voltages.

Be sure to check for proper rotation of the motor and by reversing any 2 leads of the primary source voltage you will change the rotation for the motor.

This can also be done using two contactors by having L1,L2,L3 connected to the first contactor and also the additional contacts mounted on top of the second contactor.

L4,L5,L6 are connected to the second contactor. The important thing to remember is to use an interlock which fits into both contactors when they are clipped together. This stops both contactors operating at the same time!!! ( the additional contacts mount on top of a contactor and are mechanically connected to it so that they act together)

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13y ago
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15y ago

A three phase motor will not work on a 2-phase power supply, it needs a 3-phase power supply.

Two phase electrical services are no longer the standard for electrical distribution. You would need to get an expensive phase-changer to convert your normal single phase power supply to three phase. Depending on the power output you require from the motor, it can often be much cheaper to buy a suitable single phase motor, new or secondhand, instead of buying a phase-changer as the power supply for a three phase motor.

If you really do want use that three phase motor you may find it worthwhile to contact your electricity supplier first, to ask if they can install a three phase service for you to use and what the cost would be. Otherwise, after you have bought the expensive phase-changer unit, you may find out later that your electricity supplier could have upgraded your service to three phase for a lower cost!

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14y ago

A three phase motor requires a three phase power supply. You can not run a three phase motor on a single phase power supply unless you provide some kind of converter, such as a motor-generator set or an inverter. You might be able to get the motor to rotate on single phase, if you provide starting torque somehow, but you will not get rated power in that configuration.

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14y ago

It depends , on the situation you need this setup to work .

if you need a fix speed up or down grade , the gear box is the fast solution , or if you need variable speed , you better offend go with a frequency drive , or soft start , that can give you lots of flexibility

regards

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12y ago

Hi guy its good question, pl connect one ac drive vary the two speed its possible, also you asked reverse option in the drive to supplier ,otherwise pl use 2 contactors configure with plc or pushbutton

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14y ago

You install a three phase, two speed fan motor switch. You'll need to get it from an electrical parts dealer, it's not a Home Depot or hardware store item.

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