How much speed of a motor we can increase beyond rated speed with the help of VFD / Ac drive


In certain applications we need to increase the speed of a motor beyond its rated speed in such cases before increasing the output hz of VFD you should consider few things.


  1. Load

Load on the shaft of motor should be considered. If load is too high and motor is drawing full rated current than you should not Increase the speed of motor. If you do so motor may not be able to drive the load.  When you increase speed beyond rated RPM. Output torque of  VFD will drop.

If you still need to increase the speed of motor we suggest to replace motor and VFD to one size higher as per your application.


  1. Capacity of Motor

You will need to check whether your motor can run at high speed. Because most of the motors are not meant to run at high speed above rated speed. Bearings of motor are designed to run motor at rated RPM.  You can easily increase speed by 10-15% without any harm. But if you need to increase speed above than you use special motors which are designed for High RPM.

You can easily find many VFDs which can give output Frequency above 400Hz




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3 Thoughts on “How much speed of a motor we can increase beyond rated speed with the help of VFD / Ac drive”

  • I have found VFD drives to be the only way to control AC motors reliable. However I have ran into problems using certain pnp inductive proximity sensors for counters . I once tried a 1HP DuraPulse drive from automation direct and found that when I used a AK1-AP-3A, 18mm PNP 3WiRE DC N.O, 2m CABLE W/SHLD I received noisy signals, missed counts and even locked up my laptop while monitoring CLICK PLC. Just wanted to know if anyone else has experienced similar problems and what they did to filter out the noise?

    • you can change carrier frequency (switching frequency and check whether problem is solved. also check whether any other microprocessor based system is creating a noise

  • VFD or VSD are good alternatives to the use of 1. control valves in corrosive/dirty/abrasive applications, and, 2. applications where spill back (reverse flow) conditions cannot be stopped by conventional means, e.g. NRV, instead the dynamic braking features of VFD/VSD are ideally suited to overcome this.

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