Submitted pump motor 230V,3ph but connected to 208V,3ph power

[victor.cherkashi]

1 horse power motor data of condensing water pump states the rated voltage of motor 230V,3ph.
Contractor affirms that there is no problem to connect the pump to 208V,3ph source and he did hundreds of them this way.
I understand that the performance of the pump may be 10-15% less that graph of pumps. it's not a problem.
Other than performance, is there any issue with NEC compliance or any additional requirements?

 

[MAC702]

Is it not possible to give the specific model number of the pump?

 

[victor.cherkashi]

Is it not possible to give the specific model number of the pump?

https://drive.google.com/open?id=1KwmnqW_9Vm8zSd6httsyeKIX_-Xf4n8_

 

[retirede]

It looks like a 1 HP motor with 1.15 SF and the pump never requires more than about 0.8 BHP. Probably OK with good power and no extreme ambient conditions.
The performance of the pump will not change either the lower voltage - speed will be the same.

 

[Jraef]

MOST 230V 3 phase motors 5HP and under are designed to accept 208 or 230V because 208V is a lot more common. It's doubtful that you will notice any appreciable difference in performance, the running current will just be a little higher. The pump will not run slower because the speed is based on the frequency, not the voltage. besides, your pump only needed .7HP at rated flow, the motor is 1.0HP with a 1.15 Service factor. You will never notice a difference...

 

[dkidd]

It will probably work.

I wouldn't do it unless the nameplate gave 208 as acceptable.

It will probably run at reduced efficiency.

 

[victor.cherkashi]

Below is my topic summary from the forum inputs and additional research.
1. mechanical output performance doesn't change since the RPM depends only on frequency of source.
2. since the voltage goes down by 10%, the current will go up by 10%. mybe it will require some adjustments to overload protection.
3. since the resistance of winding doesn't change, the created heat will go up by 20% that can lead to some motor headache caused by fever. you can get blamed once something happened to a motor even the problem was different.
bottom line - better to avoid this situation.

Sent from my ONEPLUS A6013 using Tapatalk

 

[retirede]

Below is my topic summary from the forum inputs and additional research.
1. mechanical output performance doesn't change since the RPM depends only on frequency of source.
2. since the voltage goes down by 10%, the current will go up by 10%. mybe it will require some adjustments to overload protection.
3. since the resistance of winding doesn't change, the created heat will go up by 20% that can lead to some motor headache caused by fever. you can get blamed once something happened to a motor even the problem was different.
bottom line - better to avoid this situation.

Sent from my ONEPLUS A6013 using Tapatalk

1: Yes
2: No - the increase in current will be more than the ratio of voltage. And the motor overload protection should not be adjusted. Standard class 20 overload protection should be fine here.
3: No - based on the data supplied, I would have no problem running this pump on a 208 V system.

 

[Jraef]

Below is my topic summary from the forum inputs and additional research.
1. mechanical output performance doesn't change since the RPM depends only on frequency of source.
2. since the voltage goes down by 10%, the current will go up by 10%. mybe it will require some adjustments to overload protection.
3. since the resistance of winding doesn't change, the created heat will go up by 20% that can lead to some motor headache caused by fever. you can get blamed once something happened to a motor even the problem was different.
bottom line - better to avoid this situation.

Sent from my ONEPLUS A6013 using Tapatalk

Conceptually that is OK, but the numbers are not as absolute. Current is dependent upon load, and load in a pump is flow, head and pressure, which in a pump motor translates to speed and torque. Speed will not change, but torque varies by the square of the change in voltage. So when your voltage drops 10%, the peak motor torque drops by .9 x .9, or 19%. So that means that to keep spinning at the same load conditions, the motor will need to draw more current. How MUCH more is not as simple as you may think. For example if the flow and head requirements by the pump from the motor are still below the motor's capability, it may run slightly warmer than it would at 230V, but that might not actually run hotter than the motor is CAPABLE of. Given that in this case the normal load by the pump at rated flow is only 70% of the motor's normal capability and only 60% of the motor's service factor capacity, I would not expect to see any appreciable loss of life in that motor.

 

[topgone]

Motor torque is reduced

Motor torque is reduced

1 horse power motor data of condensing water pump states the rated voltage of motor 230V,3ph.
Contractor affirms that there is no problem to connect the pump to 208V,3ph source and he did hundreds of them this way.
I understand that the performance of the pump may be 10-15% less that graph of pumps. it's not a problem.
Other than performance, is there any issue with NEC compliance or any additional requirements?

Motor torque changes to the square of the voltage change. In your case, the motor torque developed will only be (208/230)^2 = 81.7%. Assuming your motor is loaded full, your motor will be overloaded when the supply is just 208 V. With regards to NEC requirements, if you installed motor controllers based on 230V ratings, you will most likely have underrated elements, IMHO.

 

[Cow]

It will probably work.

I wouldn't do it unless the nameplate gave 208 as acceptable.

It will probably run at reduced efficiency.

I agree.

If it fails, guess who eats crow and gets to pay to replace it? And then do it the way they should of done it the first time.

It makes more sense to me to throw a buck/boost at it now and then you know you couldn't have done any more. At that size, it's reasonably inexpensive.