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380V Motor

01/10/2016 5:24 PM

Hi Gents.

Was shown how to connect 3phase 380 v motor to 240 v single phase (live and neutral) 22 years ago. i'm very rusted. Please help.

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#1

Re: 380 v motor

01/10/2016 5:30 PM

That would be of interest to a number of readers, especially if the motor were required to turn after being energised. Do tell.

<...very rusted...>

There are a number of ways to get rid of rust:

  • Wire-brushing
  • Pickling
  • Mechanical abrasion
  • Etc.

Don't forget to paint it afterwards.

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#7
In reply to #1

Re: 380 v motor

01/12/2016 3:23 AM

GA

I'm with you!!!

http://www.theautomationstore.com/3-phase-electrical-power-from-single-phase/

I treat it as a fairy tale, but I could be wrong.....

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#2

Re: 380V Motor

01/10/2016 7:21 PM

That's OK. Nothing has changed except the codes. NFPA.

You can get the latest codes here: Codes and standards

You are probably OK doing it the same way as before.

I'd add WD-40 to the list of solutions to rust removal offered by member PWSlack.

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#3

Re: 380V Motor

01/10/2016 7:55 PM

You'll need to connect electrical wires:

If your motor is a 220/380 Volts motor, you can probably use it.

Connect the motor in delta between 2 wires and power it up. You will hear a humming sound. If that motor needs to spin, you will need to make it spin by giving the shaft a turn. You can still spin it 2 ways, left and right. Watch your fingers.

If you want to use that motor, you can make an artificial 3rd phase with a capacitor.

You connect the 3rd wire of the windings, that is left over with one side of a capacitor and the other side of the capacitor back to one of the 2 wires you have the motor already connected to.

You will notice that you can change the rotation direction by using one or the other.

Your capacitor has to be 240 volts AC or higher.

Once you know the RPM of the motor and the Power in kW or Hp, and the working frequency of your source, you can calculate the value of the capacitor in MicroFarad.

While this works, your motor will perform less than on a 3 phase system.

This method is called the Steinmetz circuit.

The capacitor:

C= P X 10|6 / (2 pie X f X 0.87 X U|2 X n)

C in micro F, P in Watts

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#4
In reply to #3

Re: 380V Motor

01/11/2016 4:56 AM

The more motors in the system the better it works.
I've not built one of these since i was an apprentice.

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#6
In reply to #4

Re: 380V Motor

01/11/2016 10:52 PM

I've been in the electrical/ electronic industry for 40+ years. I don't ever remember seeing this circuit. Question: Are S and R timed relays or pushbutton?

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#10
In reply to #6

Re: 380V Motor

01/13/2016 11:02 AM

More basic than that, a DPDT toggle switch. The pilot motor is very slow running up to speed. I suppose a centrifugal switch could be used to operate an equivalent relay.

There are other starting methods, ranging from a piece of string to a single phase pony motor. The pony motor has the advantage of acting as a flywheel for the pilot when other drives start.

Subsequent motors in the system start DOL or Y∆. They run up to speed as per normal(ish).

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#12
In reply to #10

Re: 380V Motor

01/18/2016 8:07 PM

Thanks for the help.

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#11
In reply to #6

Re: 380V Motor

01/13/2016 3:54 PM

Just for you + I was bored this afternoon.

Both self starting, the bit of string is a bit risky.

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#5

Re: 380V Motor

01/11/2016 3:27 PM

Thank you to dvmdsc and TonyS. Exactly what i was looking for. Appreciate the explanation as well

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#8

Re: 380V Motor

01/12/2016 5:24 AM

If it's a small motor (less than 3HP), why not using a variable frequency drive?

Than you can have the nominal torque out of your motor.

Keep in mind that the motor must be a 220/380 D/Y motor, a motor 400V Delta or 380/660V will not work.

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#9
In reply to #8

Re: 380V Motor

01/12/2016 12:09 PM

That would be the easiest to implement and the best choice for efficiency.

We're all trying to 'reinvent the wheel'/'build a working wheel' and you turn us around to reveal that we're in front of a Tire Store.

GA for that.

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Users who posted comments:

adreasler (1); Andy Germany (1); dvmdsc (1); jjvan (1); lyn (1); Munster (2); PWSlack (1); rudy.leurs (1); TonyS (3)

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