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Three Phase motor on Single Phase with VFD

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Andrew Schembri26/12/2021 11:54:22
1 forum posts


I bought a Chinese VFD off E-bay and I am having a couple of issues and looking for help.

This is the model: See CofC

Motor is rated 1.1kw 415V in Y ( I have wired it in delta 220V ). Supply to VFD is single phase 220V. All seem to be wired correctly, however the motor has little to no power and runs very slowly at 50Hz.

Anyone has any ideas?

I have checked motor windings ( all ok) and continuity of wire going between VFD output and motor. I cannot check voltage with multimeter at motor terminals due to the SPWM output of the VFD. Anyone has expecience with scoping the terminals of the motor to check what is actually going on? Seems to me that either voltage being supplied is low or a phase is missing.



Edited By JasonB on 26/12/2021 12:55:05

Emgee26/12/2021 13:04:41
2404 forum posts
285 photos


Check the top menu bar for INBOX, you have a message.

John Haine26/12/2021 14:47:48
4622 forum posts
273 photos

Hi Andrew, when wiring a star connected motor to delta, it is possible to get one of the windings connected in the wrong sense relative to the other two. This matters because in a 3ph motor the windings are mutually coupled and all the couplings need to be in the same sense. So, if you called the windings A, B, and C, with ends marked 1 and 2 on each, assume to start with that all the "2" ends are connected to the star point. Then the correct delta connections should be:

A2 to B1
B2 to C1
C2 to A1

...and the 3 phase supply connects to A1, B1, C1 just as for the star connection.

If this has happened to you it may account for what you observe.

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