Speed control for 1-phase 480v motor

DerekM

Member
Location
Memphis, TN
Occupation
Electrician
Hi,
Does anyone know of a product out there were I can control the speed of a single phase 480 volt fan motor?
I have searched for the past couple of hours and the only single phase drives I have found go up to 240 volts.
 

StarCat

Industrial Engineering Tech
Location
Moab, UT USA
Occupation
Brewery Engineering Plant Technician - HVACR Electrical and Mechanical Systems
There have been for many years HVAC controllers for this duty. The classic example is called " Motor Master " and was made by Carrier for their commercial product. They require motors that are specified to run with this type of drive, typically with ball bearings. Back in the day they were characteristically noisy.
There are 480V single phase models available.
There are choices at large. Some using temp sensing, and some using pressure for input control.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
I have never in my 40+ years in industry seen a 480V single phase motor. I have seen 277V single phase motors that are fed from one phase of 480 and Neutral, but never 480V single phase. That said, I just learned that they exist... There's my new piece of useless info for the day!

There are some small VFDs that will not trip out on an output phase loss, and will accept a single phase 480V input. Allen-Bradly PowerFlex 4M drives are like that. You would need to select it based on the motor nameplate FLA, NOT by HP.
 

Russs57

Senior Member
480 VAC single phase motors are very common as condenser fan motors. Many have speed controllers based off head pressure. Penn offers a few options.

Not sure what your application is. Tell us "the rest of the story" and we will be in a better position to help.
 

StarCat

Industrial Engineering Tech
Location
Moab, UT USA
Occupation
Brewery Engineering Plant Technician - HVACR Electrical and Mechanical Systems
I have serviced all kinds of Unitary Package RTU gear with 480V single phase condenser fan motors. The Capacitors on those are notorious for holding a charge which can get you some surprises if you are shooting trouble in a control panel that is supposed to be fully de-energized and you have failed to remember this point. I have installed Scores of the Carrier Motor Master controls on their package and split units. I have seen 277V single phase fan drive motors in Fan Powered Boxes typically seen in Multi Story applications. They are less common in my experience.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
480 single phase fans are quite common on commercial AC units, I’ve had guys mistakenly use them to check rotation when hooking up temporary generators. Used to be able to use the indoor fan to check rotation, but a lot of the units now have been retrofitted with Vfd’s, so that is no longer a usable method.
 

DerekM

Member
Location
Memphis, TN
Occupation
Electrician
480 VAC single phase motors are very common as condenser fan motors. Many have speed controllers based off head pressure. Penn offers a few options.

Not sure what your application is. Tell us "the rest of the story" and we will be in a better position to help.
The fan is similar to an industrial wall mounted unit. It is used to blow dust away from a product as it falls off of a conveyor. It has a 1/2 HP motor on it.


I have never in my 40+ years in industry seen a 480V single phase motor. I have seen 277V single phase motors that are fed from one phase of 480 and Neutral, but never 480V single phase. That said, I just learned that they exist... There's my new piece of useless info for the day!

There are some small VFDs that will not trip out on an output phase loss, and will accept a single phase 480V input. Allen-Bradly PowerFlex 4M drives are like that. You would need to select it based on the motor nameplate FLA, NOT by HP.
I have 3-phase 480 close to where the fan is, I started looking at drives but couldn't find one where it said the output phase loss could be disabled.
None of the sales reps around here could understand what I was wanting either. I am going to call Yaskawa when I have time and see if they have a drive that will do what I need. If not, I will definitely look into the AB 4M.

Thanks
 

Russs57

Senior Member
Okay DerekM, what would be the variable that would be measured to tell the VFD what to do? Static pressure in the duct work?

Honestly is doesn't sound like an application that needs a VFD but I don't know all the details.

A 3 phase 480 VAC 1/2 HP motor is rather cheap. I'd be inclined to look at replacing the single phase motor. It will be more reliable and energy efficient.

If you have multiple conveyor stations it almost sounds like VAV boxes might be the better solution.

Just throwing ideas out there.
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
The fan is similar to an industrial wall mounted unit. It is used to blow dust away from a product as it falls off of a conveyor. It has a 1/2 HP motor on it.




I have 3-phase 480 close to where the fan is, I started looking at drives but couldn't find one where it said the output phase loss could be disabled.
None of the sales reps around here could understand what I was wanting either. I am going to call Yaskawa when I have time and see if they have a drive that will do what I need. If not, I will definitely look into the AB 4M.

Thanks
Better double-check your motor and make sure it is not a cap start. If it is it cannot be slowed down.
 

paulengr

Senior Member
The fan is similar to an industrial wall mounted unit. It is used to blow dust away from a product as it falls off of a conveyor. It has a 1/2 HP motor on it.




I have 3-phase 480 close to where the fan is, I started looking at drives but couldn't find one where it said the output phase loss could be disabled.
None of the sales reps around here could understand what I was wanting either. I am going to call Yaskawa when I have time and see if they have a drive that will do what I need. If not, I will definitely look into the AB 4M.

Thanks
4M was discontinued a while ago. Any fan/pump drive can disable output and input phase loss. If you don’t do this in 3 contactor bypass arrangements or nuisance trips.

But your approach is way off base. A single phase motor can’t be controlled with a 3 phase VFD even if you “single phase it”. You will have stall issues. There are single phase VFDs but they are limited to permanent split pole (PSC) motors. If this is what you have (this is the application they are used on), it might be an option. PSC VFDs are also ridiculously over priced. It is well worth it just to get a three phase fan.
 

paulengr

Senior Member
And if your rep cannot answer that question, do not expect ANY support. From memory all of the Teco 510 series have it (look at E510), Benshaw SG series, Schneider 300, 600, 900, ABB ACS and ACH.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
4M was discontinued a while ago. Any fan/pump drive can disable output and input phase loss. If you don’t do this in 3 contactor bypass arrangements or nuisance trips.

But your approach is way off base. A single phase motor can’t be controlled with a 3 phase VFD even if you “single phase it”. You will have stall issues. There are single phase VFDs but they are limited to permanent split pole (PSC) motors. If this is what you have (this is the application they are used on), it might be an option. PSC VFDs are also ridiculously over priced. It is well worth it just to get a three phase fan.
PowerFlex 4M in NOT discontinued, it is a current valid product. Don't know where you heard that but it is not at all true.

The VFDs for single phase PSC motors are indeed over priced, but they are also limited to 240V, so they are not really an option here. That's why I mentioned the PF4M, because I know it does not trip on output phase loss. I have seen people use a PF4M for single phase 230V PSC motors and it works, so I don't see why it would not work at 460V.

Yes, it would need to be a PSC motor.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Is there a limit to how far off normal frequency a PSC motor can start or run? Clearly the phase shift between windings will be different from that designed when a lower driving frequency is supplied.

Sent from my Pixel 4a using Tapatalk
 

paulengr

Senior Member
Is there a limit to how far off normal frequency a PSC motor can start or run? Clearly the phase shift between windings will be different from that designed when a lower driving frequency is supplied.

Sent from my Pixel 4a using Tapatalk
On a fan application needs almost no torque at zero speed so the only limit would be self starting. On a lot of soft start setups I often see cases where the starting voltage is too low so it just hums for a couple seconds then accelerated once it gets to starting torque. This would be.no different.

Info on discontinued PF 4 and 40: directly from the local McNaughton-McKay distributor who is pushing the 525s.

I keep thinking how many water plants would eat it up if I built a single phase VFD compatible with the far more common capacitor start/rub 3 wire motors.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
PF4 is on it's way out, the PF4M is a slightly different version (line in the top, load out the bottom) and will remain.

PSC motors are used almost exclusively on centrifugal loads like pumps and fans, which will cease to function anyway at low speeds, generally between 30-40% speed as the lower limit.
 
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