Question

What considerations do I need to investigate to run the motor beyond 60Hz?

Answer

You must understand the basic volts per Hertz relationship. When the frequency is raised to it’s base frequency of 60Hz (for this example, your base frequency can be changed,) your voltage is equal to maximum output voltage 460 VAC (also for this example.) At this point, the motor is maximum output on voltage, but you can increase your frequency and overdrive the motor. Since the drive cannot increase voltage to maintain a constant ratio, torque is eroded by inverse relation to frequency. You can estimate your torque relationship by the following formula:

 Max speed is 75 Hz, Base speed is 60Hz
 T max = T base x (ratio of base/max)
 T max = 100% x (60/75)
 T max = 80%
 The maximum amount of torque available at 75Hz is 80%.

Some considerations:

 A TENV motor is always a good idea when overdriving, no fan means less drag on motor, increasing torque a marginal amout.
 Contact the motor manufacturer to verify that the motor can handle being overdriven both electrically and mechanically (bearings.)

---

FAQ Subcategory: None

This item was last updated on 2001-08-23
Document ID: 815

---

The information provided in the AutomationDirect knowledge base is provided "as is" without warranty of any kind. AutomationDirect disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall AutomationDirect or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if AutomationDirect or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion of limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.