leitmotif
Member
Dick
this is all based on a separate post from Kid PLC. I have recopied relevant info to ensure I am not repeating partial truths - I hope.
I put these questions in a separate post to avoid taking Kids post on a tangent.
DICKDV
Assuming across line starting and no change in the power train the motor drives
I do not see how changing the same NEMA 30 HP nine lead motor from 230 to 460 will gain HP.
Another poster said
QUOTE Surely this is one of those (infamous) 2-voltage, 9-wire motors? If so, you can almost double its power output at twice the speed if you connect the motor windings for 230V and hook it to a 60HP-460V VFD. Base frequency would have to be set to 120Hz; base voltage to 460V. In other words, the motor will be able to deliver (almost) the same torque at 3600rpm (motor power = 60HP) as it does at 1800rpm (motor power = 30HP). UNQUOTE
I sorta follow this
Motor is same ie 30 HP 1800 RPM at 60 Hz
ASSUMING No changes of mechanical setup in the driven load.
120 HZ = 460 volt and 60 Hz = 230 volt
torque is constant because he has set baseline at 120 Hz.
I do not see how he can drive a 230 volt connected motor at 3600 RPM and corresponding 460 volt without burning it up. For sure I do not see how he can deliver continuous double rated motor HP without burning motor up.
I also have done a little with IEC six lead motors and understand what they are doing. Seems like a good option with differing advantages.
I do not understand how HP can change by changing from delta to wye configuration when you change the line voltage of course.
I do not want to waste a lot of your time
- but I do want to gain better understanding of what is being done here and why it can work
- can you refer me to some reading material please?
Dan Bentler
this is all based on a separate post from Kid PLC. I have recopied relevant info to ensure I am not repeating partial truths - I hope.
I put these questions in a separate post to avoid taking Kids post on a tangent.
Sparkz, I find it amusing that you refer to our marvelous dual winding dual voltage NEMA motors as "infamous"! As you point out, they can be handy for getting more hp out of a motor in a way somewhat similar to using an IEC motor to get more than nameplate kw. However, in the case at hand here, we still don't know if the power train reduction ratio can be easily changed or not. If not, your clever solution won't work. If yes, then your solution is easily the best and cheapest under the given circumstances especially if there is no room for a larger motor. Let's see what PLC Kid comes back with for a power train.
DICKDV
Assuming across line starting and no change in the power train the motor drives
I do not see how changing the same NEMA 30 HP nine lead motor from 230 to 460 will gain HP.
Another poster said
QUOTE Surely this is one of those (infamous) 2-voltage, 9-wire motors? If so, you can almost double its power output at twice the speed if you connect the motor windings for 230V and hook it to a 60HP-460V VFD. Base frequency would have to be set to 120Hz; base voltage to 460V. In other words, the motor will be able to deliver (almost) the same torque at 3600rpm (motor power = 60HP) as it does at 1800rpm (motor power = 30HP). UNQUOTE
I sorta follow this
Motor is same ie 30 HP 1800 RPM at 60 Hz
ASSUMING No changes of mechanical setup in the driven load.
120 HZ = 460 volt and 60 Hz = 230 volt
torque is constant because he has set baseline at 120 Hz.
I do not see how he can drive a 230 volt connected motor at 3600 RPM and corresponding 460 volt without burning it up. For sure I do not see how he can deliver continuous double rated motor HP without burning motor up.
I also have done a little with IEC six lead motors and understand what they are doing. Seems like a good option with differing advantages.
I do not understand how HP can change by changing from delta to wye configuration when you change the line voltage of course.
I do not want to waste a lot of your time
- but I do want to gain better understanding of what is being done here and why it can work
- can you refer me to some reading material please?
Dan Bentler