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Students Click Here



Hi there

We are 2 students from Belgium and we need some help with our project.
So our project is an automatic cowbrush. Maybe silly but I am a famrmer so it's usefull for the future. :)
So we don't know how to change the direction of our 3 phase motor. We also want that when there's to much resistance, the motor stops.
To build it in real life, it needs to be as cheap as possible. Is there anyone that could maybe help us? We would reaaly appreciate it.

Thanks in advance


RE: Cowbrush

Direction change during operation, ie backwards and forwards, is this what you are asking?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Cowbrush

You should look up VFDs. That's what's needed for this project. About half of them have built-in PLCs that would allow you to program things like time on and reversing and stopping on too much load. They also allow you to bring the speed up smoothly instead of banging on and off and electromechanical forward and reverse contacts. A VFD also avoids chattering and over used contacts.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Cowbrush

Exchange or interchange any two of the three supply conductors and the motor will reverse.
If a motor is called upon to drive to much load, heat will be generated internally in the motor windings.
Light overloads may shorten the expected life of the motor.
Heavy overloads will lead to rapid motor burnout.
An industrial induction motor will typically stall at 2 times to 2 1/2 times full load torque.

Ohm's law
Not just a good idea;
It's the LAW!

RE: Cowbrush


An industrial induction motor will typically stall at 2 times to 2 1/2 times full load torque.
And, if the overloads don't trip in less than 3 seconds the smoke will pour out of the motor.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Cowbrush

Ohm's law
Not just a good idea;
It's the LAW!

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