Three phase wiring problem

hotrod

Member
H
Join Date
Aug 2005
Location
ohio
Posts
48
What we have is a three phase motor with six wires and no idea how it was wound , not low voltage or high. My question is that we know the wires should be in groups of two but cannot determine which wire goes where, the last motor had color coded wires.o_O
 
It sounds - given its kW rating - like it has a star/delta starter.
If the rating plate does not give another rpm then discount two speed.
Check out the starter/control panel. star delta will have three contactors and a timer for the drive.
 
Check your leads, if they are sets of 2 tie any 3 that don`t come out on each other together. hook your lines to the remaining 3 leads and the motor will be hooked up star for high voltage.
 
This is what you need to do. Between any of the 6 wires, you need to get 3 windings. This can be determined by using a multimeter and reading the ohmic value of each winding. In order to determine the phase rotation, you can connect a DC source across 1 of the windings, and with the multimeter set on DC voltage, check the rotation on the other 2 windings. To confirm, take any of the tested 2 windings, connect the DC source the this and repeat the procedure. Mark them as you do your testing.
 
Alright I should specify that all six wires are used, not having three tied together. sets of two per line coming into the box.
 
Open the peckerhead and make sure none of the wire ends are touching each other. Take 2 wires and measure resistance between them. When you measure a low resistance between 2 of the wires you have now located one winding. Mark them U1 and U2. Now check between 2 more wires until you get a low resistance. Mark these as V1 and V2. The last 2 wires are now W1 and W2.

Now if you want a delta configuration, connect U1, W1 and L1 of your incoming power together. Connect U2, V1 and L2 of your incoming power together. Now connect the remaining three wires together and bump for rotation.

If you want a wye (star) configuration, connect U2, V2 and W2 together. Then connect L1 of the incoming power to U1, connect L2 of the incoming power to V1, and L3 of the incoming power to W1. Bump for rotation.
 
muusic_man

How do you know which end of the winding is U1 or U2? It DOES make a difference.

For one way to determine the relative start and finish of the windings, have a look at THIS thread in the Engineering Tips Forum, particularly the response from Wiretwister on 30 Apr 06.
 

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