3 phase rotation direction?

Jan 26, 2011 36 Replies

I thought of that. Smallest gear motor I could find cheaply was 1/2 HP!

I will have to rearrange my troubleshooting schedule so that 'rotation direction' is at the top of the list.

--Winston

Hey Winston,

I don't know what "the Borg" is, but any industrial/wholesale electrical supplier should have "Reverse Phase" relays available. Just do a Google to see them. Most have a secondary function to drop out if the applied voltage goes too low, and the really expensive ones check for over-voltage too.

Take care.

Brian Lawson, Bothwell, Ontario.

Hi Brian,

'The Borg' is an affectionate diminutive for the various mega stores who have assimilated all of our small 'mom and pop' hardware stores. over the last 15 years or so.

Thanks for the 'reverse phase' relay suggestion. As Spehro mentioned, there are many tools available that provide more information at reasonable price points.

Spehro pointed out this- and other similar tools. It is priced about the same as the relay but will display phase information from a motor disconnected from power. A very nifty trick!

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Thanks!

--Winston

I've seen three phase motors down to about 1/10 HP (small fan), but those are really difficult to locate through any normal US sources.

Oriental motor makes 3 phase gearmotors as small as 6W. Not cheap new (around $75 for a motor, ~$150 for a gearmotor) but there are usually quite a few on ebay.

"SW" in the part number signifies 200/220/230V 3 phase.

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If anyone is interested in fractional HP 3-phase motors, I have a couple. O= ne is 90 watts with a keyed shaft. One is 180 watts, with a "V" pulley, als= o keyed. Both are 220 V 3-phase and both have a variable speed box between = the motor and a speed reduction box.

Both came from a German-made wave solder machine. The 180 watt unit ran the= solder pump and the 90 watt unit ran the conveyor chains.

Would trade for something useful!!

Paul

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In that 'price ballpark', I would just buy one of the purpose-built testers cited by Spehro, for example.

Of course, if I happened to have one of those neat motors in my 'stock of spares', I would definitely put it to use.

Thanks!

--Winston

I could strip out the PWM drivers from a brushless fan motor and drive the windings via step down transformers, conceivably. The test instruments revealed earlier still sound like the best bet, (time and money wise) though.

--Winston

I've seen small fans that run on three phase, muffin fans.

John

Of course! BLDC (BrushLess DC) motors have a little three- phase oscillator, but to use one of those for phase testing you'd have to hack into it and bypass the internal 3-phase oscillator.

Good Luck! Rich

The GRC-106 had small three phase 400 Hz fans.

How about a small, inexpensive 3-phase motor?

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For me, the instruments Speff indicated are much less time and about the same money as a small motor, so I'm going with the instrument rather than the motor. Three of us had the same idea so it'd be a worthy notion if it weren't for the good quality tools Speff mentioned.

--Winston

But shiny new made-offshore electronic instruments are so sterile, lacking the character and ambience of a small but suitably grungy

3-phase motor of suitable antiquity. Have you no principles, mon?

If memory serves (and it may not), many years ago, the phase testers actually had a little 3-phase motor with one of those hypnotist spiral disks behind a clear window.

If I were shorter on money than time, I'd salvage the motor of a 3 phase brushless fan by liberating it's circuitry and driving the windings directly via three carefully chosen capacitors.

--Winston

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