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What are the implications of using a 45kW ACS580 ABB VSD on a 22kW induction motor?

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  • \$\begingroup\$ On top of what Neil said, I'm thinking there may be a protection setting on the very low end of the speed spectrum which may also need adjusting. Your manual will tell. I would be very suprised if anything breaks. \$\endgroup\$ – winny Mar 21 '18 at 7:49
  • \$\begingroup\$ Will I be wrong if I set all parameters as per motor name plate? \$\endgroup\$ – Cooh Mar 25 '18 at 5:22
  • \$\begingroup\$ No, that should fix everything for you. \$\endgroup\$ – winny Mar 25 '18 at 9:32
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It means the ACS580 will run nice and cool. The motor will only take the power it wants.

If it has programmable current limits, you may want to halve the default settings, to help protect the motor if it became overloaded, though the primary protection for this would be a thermal trip on the motor itself.

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  • \$\begingroup\$ Thanks Neil..I will set all the motor parameters as per name plate. \$\endgroup\$ – Cooh Mar 25 '18 at 5:20
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You're spending more money than you need to. If you have one "Lying around" no problem, but if we double rate every component and have to buy the equipment your wasting money.For example, If your motor only needs to do 10kw of work why would you use a 22kw motor? inefficient, also if you have a constant load on the motor just use the VFD for starting i.e. switch the motor DOL once it's running instead of running the VFD constantly, also inefficient.

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    \$\begingroup\$ Only if you have to buy either the ACS580 or a lower power unit. If you have the ACS580 lying around, using it will be the most economical option. \$\endgroup\$ – Martin Bonner Mar 21 '18 at 11:24
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The nominal VFD kW rating is the maximum motor kW rating. The VFD kW rating may need to be higher than the motor kW rating in various situations.

  1. The VFD output current rating must also be equal or greater than the motor full-load current rating. Some motors, such as those with more than 4 poles, may have a higher than typical current rating.

  2. The nominal kW rating is the rating for light duty use. For heavy duty, refer to the table in the manual.

  3. The drive may need to be derated for altitude or ambient temperature higher than the nominal limits. Refer to the derating instructions in the manual.

  4. If the drive is to be mounted in an IP55 enclosure, derating is required. Refer to the derating factors in the manual.

  5. If the switching frequency must be set above 4 kHz, the drive will need to be derated.

  6. Theoretically, mean time before failure (MTBF) for any electronic device is inversely proportional to component operating temperature. It may be desirable to increase the drive kW rating to reduce the component operating temperature and increases MTBF.

The VFD is designed to assure the proper performance and provide protection for a range motors of various power, current, frequency, and voltage ratings and number of poles. The drive start-up procedure requires the motor rating plate data to be entered into the drive to make that possible.

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I don't know specifically about the ABB drive but in some VFDs that use Vector Control, the settings for motor current values will not go below 50% of the rated current of the drive. This is because the current sensing devices inside of the drive have a tolerance for their accuracy and when the motor is too small PLUS lightly loaded, the Vector Control algorithm my not be able to accurately track the extremely low values of current it is seeing, which affects performance and low speed torque accuracy, which is likely why you wanted Vector Control in the first place.

If you are using a VFD in simple open loop V/Hz (Scalar) control mode, it makes no difference at all. In fact in that mode the VFD may not even know if the motor is connected or not.

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