Lakeside53
Stainless
- Joined
- Sep 28, 2007
- Location
- Woodinville, WA
I have a 1980's Howa 17x60. It has a dual speed motor 3 phase (4 pole/8 pole); 7.5 hp at 4 pole, 3.75hp at 8 pole. The motor name plate says Fuji, but the rest of the data is mostly meaningless to the question at hand.
It works great, but I need to change it from 240 to 480 to use VFD I have. I thought I'd seen most motor configs over my time, but this one is new to me.
There's 18 leads coming from the motor. No switching of the leads is required to change speeds - just remove the voltage from one set of connection points and apply the same voltage on a different set, and it changes from 4 pole to 8 pole. Edit : AND short U1,V1,W1 when applied to U2, V2, W2. Rest left for context.
The winding are arranged as 6 sets of 2 with the common point on each pair joined, hence 18 wires. All windings measure about 1.2 ohms so I assume they are all "the same"
My first thought was "easy"; it's just two separate winding sets : one for 8 pole and the other for 4. Not so... and they are all interconnected at all times.
I have drawn out the rats nest of connections and boiled it down two "interconnected" delta sets. Does anyone recognize this configuration and point me to examples I can see for 480v connections? It looks like I can maybe just change what looks like parallel deltas to series, but a lot of stuff has to go together "just right".
Even better would be a lathe manual, but the electrical diagram of the stock manual does not cover the "optional" dual speed motor.
It works great, but I need to change it from 240 to 480 to use VFD I have. I thought I'd seen most motor configs over my time, but this one is new to me.
There's 18 leads coming from the motor. No switching of the leads is required to change speeds - just remove the voltage from one set of connection points and apply the same voltage on a different set, and it changes from 4 pole to 8 pole. Edit : AND short U1,V1,W1 when applied to U2, V2, W2. Rest left for context.
The winding are arranged as 6 sets of 2 with the common point on each pair joined, hence 18 wires. All windings measure about 1.2 ohms so I assume they are all "the same"
My first thought was "easy"; it's just two separate winding sets : one for 8 pole and the other for 4. Not so... and they are all interconnected at all times.
I have drawn out the rats nest of connections and boiled it down two "interconnected" delta sets. Does anyone recognize this configuration and point me to examples I can see for 480v connections? It looks like I can maybe just change what looks like parallel deltas to series, but a lot of stuff has to go together "just right".
Even better would be a lathe manual, but the electrical diagram of the stock manual does not cover the "optional" dual speed motor.
Last edited: