Wye-Delta Starting Under Load
Wye-Delta Starting Under Load
(OP)
I have been asked to size a generator to start two 75HP motors at star-delta(wye-delta), starting on-load and at the same time.
The machine is a wood-shredder so I assume that there is a high starting torque requirement.
It seems to me though that a star delta start (with open transition) might not be suitable for starting under load.
Any comments or advice will be much appreciated.
Colin
The machine is a wood-shredder so I assume that there is a high starting torque requirement.
It seems to me though that a star delta start (with open transition) might not be suitable for starting under load.
Any comments or advice will be much appreciated.
Colin






RE: Wye-Delta Starting Under Load
respectfully
RE: Wye-Delta Starting Under Load
If the motors are fully loaded when full speed is reached then the Y-D starter will likely reduce the current very little compared to a full voltage starter. They will have to transition at a lower speed where the full voltage current will still be quite high.
Once you really understand the load and the motor starting requirements then you can start to size the genset.
RE: Wye-Delta Starting Under Load
Soft starters are ok if your start period is brief. You get about the same torque as you would with Y-D. I haven't seen many soft starters that would handle an extended acceleration period without significant oversizing. So the questions are how quickly does the load need to reach normal speed and what is the available overload capacity of the generator?
Looks like it will take one big CAT.
RE: Wye-Delta Starting Under Load
My opinion, USE A LARGER GENERATOR.
RE: Wye-Delta Starting Under Load
Colin