Does your VFD allow for wiring a two speed motor?Damn right, I have the German version and the Czech version and the Czech one is a lot better, even has the wiring schematic.
So, today I have been figuring out how to wire the 2-speed motor to a VFD and I think I've got it figured but I've never done a 2-speed one before so I'm putting it up here to see if anyone has any constructive input.
The machine has a motor that has 6 wires which can be connected to make it a 4-pole motor or a 2-pole motor, both 415V input. It's called a Dahlander winding. I've got the schematic from the manual and mapped where each connection goes for the two forward speeds and two reverse speeds. Low speed has the motor wired in 4-pole delta and high speed makes it a 2-pole star.
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Now the two top ones suit me a basic delta 4-pole winding EXCEPT that it's configured for 415v input. It's 4-pole so slow speed and I can speed the motor up with higher frequency if I need to. Only problem is that VFD is 240V input so would lose huge amounts of power connected to that motor. What I want to do, though I can't until after I get the thing home, is pull the motor apart and see if I can re-connect it like this:
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I figure if I do only one pair at a time I can make sure I keep the winding orientation right. Finding the correct ends will be easy with an ohm meter - it will read 5 times the resistance one way compared to the other. Splitting the winding pairs and putting them in parallel will put the correct (more or less) voltage across them and the direction of current will be the same in series as in parallel so they should be 'pushing' in the same direction.
That's what I'm hoping anyway. If anyone sees a flaw in my plan please speak up. I know there's a small risk of voltage spikes etc from the VFD but I'll take that chance. If it goes bang I'll swap the motor out.
The problem as I would see it is most VFD ask you to choose RPM and Poles as a set variable.