3-Phase Wiring on Electrical Motor

Not with a multi-meter, can't check the phase sequence with that! What you could do is connect the three phases to the motor and give the switch a quick jab, see if the motor turns in the correct direction, if not, change two phases so it does! There is a little meter that can check the phase sequence, it has 3 leads that you connect to the phases, press a button and an arrow spins round. If it's spinning in the same direction as the arrow, then you have your phase sequence! Hey presto!

There are of course some devices where the incorrect rotation of the motor will spell disaster a vacuum pump for instance.

In this case don't risk it, find another motor to test out the phase sequence or make sure the motor you wish to use is disconnected from its load

If there's only three terminals then it doesn't matter; all that will happen is that it will go either the right way round or the wrong way round.

If there's more than three terminals then remember that three-phase wiring usually comes in multiples of three big terminals, and everything else is a monitoring circuit of some kind. Three small terminals can relate to a resistance-temperature device [RTD] and those will be much smaller than the threes of big terminals.

Anyway, if it blows up on test then a bloke coming out of Boots' back door dropped a couple from his pocket on the way out. I've snaffled them away. Come and get one if you want it.

Yes there is a way, but you must be able to identify the nameplate ratings of the motor to start with. Can you? If so, post it (hint: ALL of it).

I think you're talking about a dual voltage motor that, for example, can be wired for 240VAC or 480VAC. That being the case, give us the complete nameplate information and if there is a separate plate defining the wiring for each voltage arrangement, give us that also. How many winding leads are there? Twelve (three pairs of four) is the usual for six windings. For the higher voltage, each group of two windings is wired in series, and for the lower voltage setting, they are wired in parallel. Once the windings have been properly paired, you'll have to deal with how the pairs are wired to the supply. Is the motor currently wired for the lower voltage or are all the winding leads hanging loose and un-connected? Get us the info on the motor and we can get started.

Most dual voltage motors I have seen have 9 wires, 3 groups of 3 and are connected in differing fashions depending on 230 or 460 application. Most of the motors I have seen have the wire number printed on the insulation, P1-P9. Not sure if its possible to use an ohmeter to figure out what wire is what if there are no marking. Good luck!

Shawn

Three phase dual voltage motors can have 6, 9, or 12 leads. They may also be a Y or Delta configuration. I would take the information from the motor name plate and contact the manufacture to get the specific configuration of the motor. Once you know this you can use an ohm meter to determine how to connect the leads for you application.

Mike

If you have a 3 phase, squirrel-cage, induction motor, which is designed for dual voltage such as 230/460, then there is a way to identify the windings. With an ohm meter you can identify the internal leads 7, 8 & 9, which are tied together. Leads 1 & 4 are together, 2 & 5 and 3 & 6.

Please post parts of this picture so we could see what it is.

Use Irfanview. A verstile program for PIX

Pointless to discuss what it could be, he needs to identify what it is.

The majority of three phase industrial motors have just three windings,or 'coils'

The ends of the coils are connected to six terminals.

With an ohmeter,or a continuity tester,connect to any one terminal,test the other terminals until you find a low resistance or continuity,this will identify the ends of one winding.

Connect to another terminal and test for the other end of the next winding.

The remaining two terminals will be the third winding,but just test to confirm.

If during testing any terminal shows continuity or low resistance with more than one terminal you've got a fault.

The windings are normally connected in 'star' for the highest voltage that the motor is rated. Connect any three ends of the windings together,the 'star' point.Dont connect this point to the supply or neutral.just leave it insulated.

Connect the free ends of the windings one to each supply phase.

If rotation is incorrect swap the connections of two of the supply wires only.

Happy motoring,oldeng.

Thank everyone for their help and comments. In the future I will try and provide more information. The name plate on this motor suffered from another persons stupidity, in that it was painted over and ended up being virtually unreadable. the wires that come off of the windings suffered a similar fate and the numbers are unreadable. so in the end, the best solution may be to send this one to the scrap heap, and replace it with a new one. However, I really hate replacing things that can still function. Once again, Thank you everyone.