I recently purchased a vertical harrison miling machine, the machine was wired for 400 volts, I connected it up to my 400 volt chinese 2.2kw vfd and the machine would only run in the lower gears and lacked any power in the high gears, I just figured my vfd was crap so I decided to try a hunyang 220 volt vfd of higher kw rating, 4 kw to be precise.
after a struggle I removed the main motor of the machine, the machine was clearly wired for star 400v connection but I also noted the motor was a 6 pole 990rpm motor of heavy construction, there were 6 wires, non of which were labeled as far as I could see, 3 black wires and 3 red wires. the 3 black wires were bolted together for the star connection and the 3 reds left the motor for l1,l2 and l3.
in my lack of wisdom I thought , just change the connection for delta , so with a multimeter set for continuity I isolated 3 pairs of wires with continuity, the coils I thought.
here is where I believe I may have messed up, the u v w wires,
I had no way, well my brain couldnt figure out which was which so in my mind I made a triangle out of the pairs of connected coils and then rotates the connections of the black uvw wires 1 place or 120 degrees and connected these new pairs to my l1,l2,l3.
I connected up my vfd to the 3 selected wires and my motor ran smoothly and at 50 hz it attained the rated rpm as I checked this with a tacho, now not the smartest but this was on a vfd I didnt care for I switched two of the black uvw wires deliberately to make a fault and sure enough the motor wouldn't run or if it did it was rough, so happy with my efforts I reinstalled my motor to my mill and connected it up to my 220 v 4kw huanyang vfd, same if not slightly worse , no power in higher two gears and after much messing about with vfd settings and torque boost settings its still the same and here I am begging your wisdom and guidance, pictures to follow soon thanks for your help!
after a struggle I removed the main motor of the machine, the machine was clearly wired for star 400v connection but I also noted the motor was a 6 pole 990rpm motor of heavy construction, there were 6 wires, non of which were labeled as far as I could see, 3 black wires and 3 red wires. the 3 black wires were bolted together for the star connection and the 3 reds left the motor for l1,l2 and l3.
in my lack of wisdom I thought , just change the connection for delta , so with a multimeter set for continuity I isolated 3 pairs of wires with continuity, the coils I thought.
here is where I believe I may have messed up, the u v w wires,
I had no way, well my brain couldnt figure out which was which so in my mind I made a triangle out of the pairs of connected coils and then rotates the connections of the black uvw wires 1 place or 120 degrees and connected these new pairs to my l1,l2,l3.
I connected up my vfd to the 3 selected wires and my motor ran smoothly and at 50 hz it attained the rated rpm as I checked this with a tacho, now not the smartest but this was on a vfd I didnt care for I switched two of the black uvw wires deliberately to make a fault and sure enough the motor wouldn't run or if it did it was rough, so happy with my efforts I reinstalled my motor to my mill and connected it up to my 220 v 4kw huanyang vfd, same if not slightly worse , no power in higher two gears and after much messing about with vfd settings and torque boost settings its still the same and here I am begging your wisdom and guidance, pictures to follow soon thanks for your help!