Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: comet on April 01, 2012, 10:41:28 AM
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Hi,
if you have a 3 phase motor running off an inverter,what frequency is the maximium torque generated at?
for example i have a 3 phase 230v motor rated 2800 at 50hrtz.
is max torque at 100% 50hrtz or at 80% (40 hrtz) ?
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A 3-phase motor driven by a VFD will have constant torque up to the motors base speed, and constant power above base speed.
Regards,
Ray L.
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ok,so what does that mean in the real world?
I know that when you over or under frequency the motor it loses power/torque is it like a dc motor that at poroduces the most power at 80% rated rpm
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It produces the same torque at any speed below its base speed, which means power below base speed falls off with RPM. Above base speed, power is constant, which means torque falls off as speed increases. So, you'll have full torque at any frequency up to 50Hz, and decreasing torque above that speed. At 100 Hz, torque will be half what it is at 50Hz. If it's a 1HP motor, it will deliver 1 HP at 50Hz and above, but only 1/2 HP at 25Hz.
Regards,
Ray L.
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right, so I will be able to use the highest feed rate with the spindle motor running at its design frequency,50hrtz.
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Not necessarily. If you're torque or power limited, then perhaps. But with smaller tool, very likely higher RPM will allow higher feedrates, but you won't be torque or power limited.
Regards,
Ray L.