Author Topic: VFD connected to Single Phase Induction Motor  (Read 300 times)

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Offline made2hack

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VFD connected to Single Phase Induction Motor
« on: February 27, 2019, 11:36:31 am »
Hi all,

I've got this induction motor which I've mentioned in a previous post: Electric Motor Specs
The motor has 4 connection points, U1, U2 and Z1 and Z2. U1 & U2 are the primary coil (approx 5 Ohm) and Z1 & Z2 is the secondary coil (approx 10 Ohm).
There is also a start capacitor of 20uF to get it started.

I want to connect it to a VFD. The VFD I have is your typical chinesium AT1/AT2 model with Single Phase In (ie 220V) and either Single Phase Output or 3 Phase Output. The output terminals are U, V, W. As per the instructions, they say to connect W and V terminals across the main coil (so U1 & U2 on my motor). And they say connect secondary coil after removed capacitor to U. So I assume to connect U to one end of either Z1 / Z2. The other end is left floating.

I cannot get the motor to start under it's own power. The VFD throws error 6 (over current). I can get it to start and work by manually twisting the motor shaft until it starts working under it's own power and then the VFD works as expected (adjust speed / frequency, fwd, reverse etc).

I am assuming I still need to connect the starting Capacitor but I'm not sure over which terminals to connect it to or how it would work together with the VFD.

Any thoughts?

Thanks,

Offline Wolfram

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Re: VFD connected to Single Phase Induction Motor
« Reply #1 on: February 27, 2019, 11:47:56 am »
The motor will not be able to start if one end of the start winding is left floating. Connect the other end of the starter winding to the corresponding end of the run winding, as you would when using it as a capacitor-run motor.
 

Offline made2hack

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Re: VFD connected to Single Phase Induction Motor
« Reply #2 on: February 27, 2019, 11:59:06 am »
Is the start winding the higher ohm one ? Ie Z1 / Z2?

Offline made2hack

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Re: VFD connected to Single Phase Induction Motor
« Reply #3 on: February 27, 2019, 12:18:49 pm »
Ok, so I got it to work by connecting one end of Z (start winding? The one with higher resistance) to one end of the running winding. It starts fine but it goes into Overcurrent at around 3.3 - 4 Amps. Before, it would be running at 1.8 Amps full speed (when only one winding was connected). Now, it cuts out not quite full power. The VFD is purported to be a 1.5KW VFD with a rated current of 8A.
 


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