The Gorton 8D Mill I just purchased has a 2 speed 3phase motor with separate windings for each speed. The previous owner had the motor rewound for 220/240 (60 cyc).
Low speed winding are T1, T2, T3
High speed windings are T11, T12, T13
From what I can tell three phase power on only one winding or the other depending on the desired speed.
The question is which set of windings to use with a VFD? Motor numbers are below.
Efficiency wise the high set seems to make sense which would require a VFD that can handle 1.5 HP.
Am I thinking on the right track here? Any reason to consider using the low rpm windings?
Ratings from original motor tag
1.5 HP, 1720 RPM, 2.3A
¾ HP, 860 RPM, 1.6A
Above was for 480V.
For 240V I expect to see 4.7A at high and 3.6A at low
Note running the numbers the low set of windings seems to be less efficient that the high. I ended up using .707 times the voltage to get at the ¾ hp wattage ratings for 480V and used that for the 240V also.
Low speed winding are T1, T2, T3
High speed windings are T11, T12, T13
From what I can tell three phase power on only one winding or the other depending on the desired speed.
The question is which set of windings to use with a VFD? Motor numbers are below.
Efficiency wise the high set seems to make sense which would require a VFD that can handle 1.5 HP.
Am I thinking on the right track here? Any reason to consider using the low rpm windings?
Ratings from original motor tag
1.5 HP, 1720 RPM, 2.3A
¾ HP, 860 RPM, 1.6A
Above was for 480V.
For 240V I expect to see 4.7A at high and 3.6A at low
Note running the numbers the low set of windings seems to be less efficient that the high. I ended up using .707 times the voltage to get at the ¾ hp wattage ratings for 480V and used that for the 240V also.
Comment