minilathe22
Established Member
I have a 3HP 3 phase motor, currently configured for 380v voltage only, so only 3 wires. I can see inside there is a star point if I wanted to carefully unpick the wires and convert it to 240v operation.
My concern is that while cleaning out some dust, a fair bit of varnish had visibly flaked off. There is 90M ohms between all of the coils and ground, which I believe is good, but when I measure between each of the 3 wires the resistence is 8 ohms between two of them but one set is 13 ohms.
I am currently using a VFD which is too small, the motor seems to run fine without any load applied. With a load applied the VFD is too small to power it.
Is this difference in resistance between phases a problem? I want to consider whether I have a solid motor before upgrading to a larger VFD. Any other tests I can do with a multimeter to determine the health of the motor?
My concern is that while cleaning out some dust, a fair bit of varnish had visibly flaked off. There is 90M ohms between all of the coils and ground, which I believe is good, but when I measure between each of the 3 wires the resistence is 8 ohms between two of them but one set is 13 ohms.
I am currently using a VFD which is too small, the motor seems to run fine without any load applied. With a load applied the VFD is too small to power it.
Is this difference in resistance between phases a problem? I want to consider whether I have a solid motor before upgrading to a larger VFD. Any other tests I can do with a multimeter to determine the health of the motor?