Quick Answer: Can I use a larger HP variable speed drive to run a smaller HP motor?

YES. In most cases a drive can control a motor with lower HP (and current) rating. The motor nameplate information will have to be entered correctly to ensure proper control of the motor and that the overload protection is enabled. In most cases the Overload protection adjustment range is the limiting factor.

Can you use a bigger VFD for a smaller motor?

An oversized VFD can be used for a smaller HP motor. The advantage of this application is that if the motor requirements increase, the VFD may be large enough to still handle the increased load.

Does VFD HP need to match motor HP?

VFD sizing should always be based on motor current and voltage, not hp.

Can I control a motor with a rating higher than that of the variable speed drive?

Bottom line: if power requirements of the driven load don’t exceed the rated power of the motor at the higher speed, then there should be no problem in operating the motor at the increased speed. If you are using a 4 pole motor you should be OK.

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Can a VFD be too big?

On a side note however, many VFD mfrs will tell you not to use a VFD that is more than 2x the motor rating, so for example your 25HP drive should not be used on anything smaller than 15HP. The problem becomes that the drive’s current sensors become out of the range of acceptable error.

How do you match a VFD to a motor?

Thus, the rule of thumb for sizing the single phase input on a three-phase drive is to use a VFD rated for 2 times the FLA of the motor. For example if your motor is a 10 HP motor with a FLA of 28 amps, then you would need to select a VFD with an amp rating of 56 amps which ends up being around 20 HP.

Can any motor be used with a VFD?

Output voltages are available for VFDs to match almost any existing motor voltage. However, very few, if any, VFDs have a direct 13,800-volt output for very high-voltage motors. For these cases, using a step-up transformer on the output of the VFD is often necessary to match the motor voltage.

How much can you overspeed a motor with a VFD?

Motors generally have to withstand 10 % overspeed. But it in no way means many motors cannot withstand much higher over speeds.

How do you tell if a motor is rated for a VFD?

Three major factors should be considered when determining if a motor is compatible with a VFD: the motor winding insulation, motor bearings and pump operating speed range.

How much is a VFD?

Typical installed costs of VFD systems range from $200 to $500 per horsepower (HP). Suppliers can assist users in selecting a VFD that is properly sized and that includes any necessary filters and reactors.

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Which motor is used for variable speed?

Variable frequency drives or alternating current (AC) motor adjustable speed drives. They are used in synchronous motors and both in wound-rotor and in squirrel-cage rotor asynchronous induction motors.

Can VFD increase motor speed?

When the VFD reduces frequency and motor speed, it also reduces voltage to keep the volts/hertz ratio constant. Torque remains at 100 percent, but HP is reduced in direct proportion to the change in speed. … When a VFD increases frequency above 60 hertz, HP and torque do a complete flip flop.

Is VFD and VSD same?

A VFD refer to AC drives only while VSD refer to either AC or DC drives. VFDs vary the speed of an AC motor by varying the frequency of the motor. VFDs referring to DC motors vary the speed by varying the voltage to the motor.

Should I oversize my VFD?

You can’t go too big, because big VFD’s may not allow adjustment of the VFD motor amperage setting low enough for a small motor. If you overloaded motor, VFD would cook it… You should be fine, with a 3kw running a 1 kw motor…

Motorization