Vfd 1.0 hp

Prayder · Jun 29, 2017

If I am using a 1.5 hp motor, can I use a 1 HP VFD to run the motor? Or would I get a fault code from the drive?

Maxkling · Jun 29, 2017

What VFD, what voltage, what's the motorload and conditions? How you line voltage? Need more info.

Pronto · Jun 29, 2017

no you can not use a 1hp VFD for a 1.5hp motor. As a rule of thumb, your VFD should have a 50% overload capacity rating over above the motor rating. Therefore, in your case the VFD should be rated at 2hp.

rQx · Jun 29, 2017

If your motor doesn't exceed the max current for the VFD I would say that it could work. However if you run the motor at low load and get it to work doesn't mean that it will work at full load.

Tom Jenkins · Jun 29, 2017

Pronto said:
no you can not use a 1hp VFD for a 1.5hp motor. As a rule of thumb, your VFD should have a 50% overload capacity rating over above the motor rating. Therefore, in your case the VFD should be rated at 2hp.

I disagree.

First, we buy VFDs by motor power rating, but they are built (and fail) based on Amps. If you have a typical duty cycle and load then your motor and the VFD's amp ratings will be a match. There is no need to pay for an over-sized drive.

Some loads, like conveyors or positive displacement pumps, have a high amp demand (high torque) at low speeds. VFD manufacturers therefore have drives rated for constant torque, which are "over-sized" and rated for the high current demand.

It may not matter much at 1 hp. If I used a 50% over-sized VFD on a 200 hp motor driving a centrifugal pump I would be throwing away thousands of dollars with no benefit to the end user.

Always, know your application, work with suppliers that you have confidence in, and engineer the VFD selection as part of a system.

Mara · Jun 29, 2017

rQx said:
If your motor doesn't exceed the max current for the VFD I would say that it could work. However if you run the motor at low load and get it to work doesn't mean that it will work at full load.

Definitely it doesn't work with full load because all rating values in the motor rating plate are given at motor rated load.

If you doesn't run the motor with the full load it's possible to use smaller vfd.

BlueAltezza · Jun 29, 2017

rQx said:
If your motor doesn't exceed the max current for the VFD I would say that it could work. However if you run the motor at low load and get it to work doesn't mean that it will work at full load.

I agree with this.

As mentioned in another reply, the drives are actually rated in Amps, not HP. Check your motor's rating and compare it to your drive's rating for a quick yes/no. I've seen close to 2A variances on the 1 HP drives I've used from various manufacturers.

Mara · Jun 29, 2017

BlueAltezza said:
I agree with this.

As mentioned in another reply, the drives are actually rated in Amps, not HP. Check your motor's rating and compare it to your drive's rating for a quick yes/no. I've seen close to 2A variances on the 1 HP drives I've used from various manufacturers.

It doesn't matter what is the rated current if you always have only partial load.

E:shaft torque is the key point

labeledas · Jun 29, 2017

I have seen it work not to say it's ideal, but one location had a 15hp drive running a 20hp motor and was a single phase to 3phase conversion as well so the drive by all accounts should have been 40hp. It has been running fine for over 2 years.

Why it was installed? Nobody bothered to pull the pump from the well to check the nameplate and took the operators word, also no engineer on job so there were more questionable items.

Why it works? I assume it is because the motor is not running at full capacity which happens to work out in this case since the lower flow keeps the well from running dry and it is simply filling a reservoir with a low demand so fill speed is not crucial.

Should it have been done? Definitely not

rQx · Jun 29, 2017

Mara said:
Definitely it doesn't work with full load because all rating values in the motor rating plate are given at motor rated load.

If you doesn't run the motor with the full load it's possible to use smaller vfd.

We don't have any data for any of the amperages of the drive or motor so we can only guess. But if the FLA of the motor doesn't exceed the drive rated current it will work on full load. Most probably the FLA of the motor exceed the drive rating but we don't know since we haven't got the data. So you can't use "definitly" when you don't know the values of the equiptment we talk about.

Bit_Bucket_07 · Jun 29, 2017

Tom Jenkins said:
I disagree.

First, we buy VFDs by motor power rating, but they are built (and fail) based on Amps. If you have a typical duty cycle and load then your motor and the VFD's amp ratings will be a match. There is no need to pay for an over-sized drive.

Some loads, like conveyors or positive displacement pumps, have a high amp demand (high torque) at low speeds. VFD manufacturers therefore have drives rated for constant torque, which are "over-sized" and rated for the high current demand.

It may not matter much at 1 hp. If I used a 50% over-sized VFD on a 200 hp motor driving a centrifugal pump I would be throwing away thousands of dollars with no benefit to the end user.

Always, know your application, work with suppliers that you have confidence in, and engineer the VFD selection as part of a system.

I agree. Oversizing VFDs by 50% is the most irrational "rule of thumb" I've ever heard of. Even in applications that require oversizing, such as starting an eccentric load, a 50% factor would be overkill.

As for the OP, we don't have adequate information to give an accurate answer. Many drives rated for 1 HP will have the capacity to operate some 1.5 HP motors. Depends upon the specific drive and motor, as well as the intended application.

Vfd 1.0 hp

Prayder

Lifetime Supporting Member

Maxkling

Member

Pronto

Member

rQx

Lifetime Supporting Member

Tom Jenkins

Lifetime Supporting Member

Mara

Member

BlueAltezza

Member

Mara

Member

labeledas

Member

rQx

Lifetime Supporting Member

Bit_Bucket_07

Member

Similar Topics