# Using a variable freq control to run a 3 phase motor on 1 phase.



## rogersmithiii (Feb 1, 2010)

Can someone offer a bit of education please?

We have a three phase, 220, 3 hsp electric motor that we need to run off of single phase 220. We purchased an appropriately sized variable frequency drive from GE to run this unit. We were told that this drive would do the phase conversion for us. Inside the cabinet of the equipment, there is a motor, along with three thermal overload relays, and a 220 v contactor.

When we depress the momentary contact start button on the motor, the contactor chatters, and arcs like crazy. Eventually (maybe 3 seconds), the motor will start. 

Three questions.

1. The drive mfger tells us that the output from the drive is not real sine wave AC. Should the output from the VFD be able to cleanly close a 220 V contactor? Is it that we might have a bad contactor, or is it that the contactor won't close with the voltage output from the VFD?

2. The drive manufacturer tells us that the drive is essentially doing the power switching to the motor, and that we could probably remove the contactor. We called the equipment manufacturer and asked them, and they appeared to have a coronary. They started screaming about safety issues, and dead workers, and liability issues, and told us that we needed to buy a new $2500 motor from them to fix our problem. They would not give us any info about how all of this works. 

Is the drive manufacturer right? Can we remove the contactor because the VF drive is switching the 220 for us?

3. There are three thermal overload relays in this unit. Will they be OK if we drive this unit with the VFD?

Any information would be appreciated.

Rog


----------



## JayH (Nov 13, 2009)

I recommend an electrician examine your installation.


----------



## vanvincent218 (Jan 8, 2010)

had an application where we were to install a 3 phase compressor motor in a mechanic garage. Butt there was only single phase..after exploring all the options. it was cheaper to just switch the motor...it sounds like whoever sold you this stuff wasnt totally informed of its application. I would implore you to call a licenced electrician and have him rethink your set up.! hope the warrenties are still good!
good luck!


----------



## rogersmithiii (Feb 1, 2010)

The problem was that the VFC wasn't compatible with the contactor. Removed the contactor and the thermal overload relays (the tasks of which are now handled by the VFC), and everything works ducky. Found some top notch techy guys at a major electric motor company, and the company that made the VFC, and they provided the necessary details.

Thanks
Rog


----------



## varmit (Apr 19, 2009)

A contactor on the load side of a VFD is a BAD idea. On some drives, if a load side contactor opens with the motor running, that can be the end of the drive. This also applies to places that want to use twistlocks at motors. Most newer drives will protect themselves from this problem, but I have replaced several older drives killed by this. 

If you need/ are required to have a "e-stop" contactor, install it on the line side of the drive.


----------



## pudge565 (Dec 8, 2007)

varmit said:


> A contactor on the load side of a VFD is a BAD idea. On some drives, if a load side contactor opens with the motor running, that can be the end of the drive. This also applies to places that want to use twistlocks at motors. Most newer drives will protect themselves from this problem, but I have replaced several older drives killed by this.
> 
> If you need/ are required to have a "e-stop" contactor, install it on the line side of the drive.


Does this also apply to the OCPD (heaters) for the motor? Should they be put on the line side? I ask because I am installing an Allen-Bradley Bulletin 1332 as a senior project. Feel free to PM me for more information.


----------



## varmit (Apr 19, 2009)

There is no reason to install a standard overload block down stream of a VFD.
The VFD has electronic overload protection built in. It is a matter of setting the motor full load amps in the correct drive parameter.

In the "early days" of VFDs, some companies insisted on an O/L block on the load side of drives. This was mainly because of misguided lack of trust in electronic O/Ls of the day. Remember, this was a time of melting O/L "heaters" and dash pots. When an O/L was installed on the load side, of a drive, the O/L relay NC contact was wired to a dive enable input or a drive stop. The O/L does not break the power leads.

Hope this helps.


----------



## varmit (Apr 19, 2009)

*Oops*

My mistake for the day:

I forgot that an AB-1332 does not have an electronic O/L in it's firmware. So you WOULD need an external O/L. Terminals 14 and 15 can be used for this purpose. Wire these terminals to the NC contact on the O/L block. These terminals serve as an "enable" for the drive.

Where did you find a 1332? They have not been manufactured since 1988.

Good luck on your project.


----------



## John Valdes (May 17, 2007)

Good job varmit!


----------



## pudge565 (Dec 8, 2007)

varmit said:


> My mistake for the day:
> 
> I forgot that an AB-1332 does not have an electronic O/L in it's firmware. So you WOULD need an external O/L. Terminals 14 and 15 can be used for this purpose. Wire these terminals to the NC contact on the O/L block. These terminals serve as an "enable" for the drive.
> 
> ...


I don't know where we got them. They have been laying around in the shop for who knows how long. They were probably donated to the school. So if i understand you correctly I take a wire from terminal 14 to one side of the NC contact and from the other side of the contact to terminal 15. I then wire the OL with L1 L2 and L3 and T1 T2 and T3.


----------



## MDShunk (Jan 7, 2007)

A VFD can often be a fantastic and cost saving option when running smaller 3-phase motors on a single phase service. The last one I did was for a second hand 3-phase Hobart dough mixer at a pizza shop. It was cheaper for me to install a VFD than it was to buy a phase converter for this machine. Changing the motor was not an option, since it's somewhat of a special motor for a dough mixer. I have a friend that has an old Bridgeport milling machine in his garage that he runs off a VFD also. He uses it for most of the speed control so that he doesn't have to mess with changing the belting around so much.


----------



## varmit (Apr 19, 2009)

pudge565 said:


> I don't know where we got them. They have been laying around in the shop for who knows how long. They were probably donated to the school. So if i understand you correctly I take a wire from terminal 14 to one side of the NC contact and from the other side of the contact to terminal 15. I then wire the OL with L1 L2 and L3 and T1 T2 and T3.


You are correct on the control wiring of the O/L. For the drive output-T1, T2, T3, would go to the line side of the O/L. From the load side of the O/L, continue on to your motor.

A 1332 is a simple and durable drive. I replaced two of them at a chemical plant two years ago that had been in service about 20 years.


----------



## pudge565 (Dec 8, 2007)

varmit said:


> You are correct on the control wiring of the O/L. For the drive output-T1, T2, T3, would go to the line side of the O/L. From the load side of the O/L, continue on to your motor.
> 
> A 1332 is a simple and durable drive. I replaced two of them at a chemical plant two years ago that had been in service about 20 years.


Ok thank you so much for the help. I have a thread started somewhere with pics of the begginings of the project. If you want more information on it let me know but I don't want to hijackthis thread.


----------



## 5volts (Jan 11, 2008)

varmit said:


> ...If you need/ are required to have a "e-stop" contactor, install it on the line side of the drive...


Expect nuisance network communication faults when installed on the line side. Operator hits a e-stop for a second and the drive starts to power down than they restart. 

Unless you power the drive with external power to maintain network comms. E-stop on the line side could be a big problem for some.


----------



## varmit (Apr 19, 2009)

p_logix said:


> Expect nuisance network communication faults when installed on the line side. Operator hits a e-stop for a second and the drive starts to power down than they restart.
> 
> Unless you power the drive with external power to maintain network comms. E-stop on the line side could be a big problem for some.


True, if you have drives on a network, however few places even require a contactor any more. Most drives, other than Seimens, do not have the capability for separate control power. I would normally only break the drive enable circuit through the E-stop. If the operator is using the E-stop, for a normal machine stop, someone needs some training. If there is a REAL need for an E-stop, faulting the network would be a minor problem.


----------



## 5volts (Jan 11, 2008)

varmit said:


> True, if you have drives on a network, however few places even require a contactor any more. Most drives, other than Seimens, do not have the capability for separate control power...


We use AB powerflex 70's and when a e-stop/safety is pushed bus voltage drops but the Ethernet IP 20 commE module maintains communications and HIM continues to stay lit. Ethernet IP takes some time to establish communications.:thumbsup: Contactor is on the line side this method works great for this app.

Another situation we had AB 1305 Drives configured for remote I/O AKA "Blue hose" and some Powerflex 70s with a 20commR module that also had E-stop contactors on the line side and we had a lot of "Undervoltage Faults" magically appearing. Operator hit a E-stop finished picking up down product after reaching in to machine and restarted.The drive never fully shutdown/discharged. Auto reset function did not solve this problem. These contactors have been moved to the load side, no more problems. Not one of these drives have failed.



varmit said:


> ...If there is a REAL need for an E-stop, faulting the network would be a minor problem...


Well not if you are the electrician who has to go reset the VFD/panel.:laughing:

Minor problem? Tell that to management or the corporate bean counters. Especially when they are having their morning production meeting and reviewing shift issues, downtime, and all faults on their central reporting program only to see EthernetFault, EthernetFault, EthernetFault, EthernetFault, EthernetFault, EthernetFault, Ethernet Fault, Ethernet Fault.............up the



varmit said:


> ...If the operator is using the E-stop, for a normal machine stop, someone needs some training...


I agree a machine cycle stop should be used for a normal shutdown. However in the "real world" operators hit e-stops to "reset" because they simply can't figure out why certain conveyors won't run or a machine will not start. Then the Electrician is called out and 20 VFDs are faulted because the contactor is on the line side of the Drive. There is a reason they are the "operator". 

Not all places use applications where they are sending ones and zeros through a communication cable. But when they are the Drive must be set up/configured/wired to operate safely and most importantly to production personnel, minimize downtime as much as possible.


----------



## varmit (Apr 19, 2009)

As I stated previously, most of the newer drives will self protect against damage if there is a load loss (contactor opens) while running. It is mainly a problem with older versions.


----------



## rogersmithiii (Feb 1, 2010)

Thanks for all of your input. Being able to use a $186 drive instead of a $800 rotary converter was a great discovery. The whole experience also gave me a great education on 3 phase motors, drives, contactors and other related issues.

The mfg of the equipment was not helpful. GE was pretty helpful, but the guy who really provided the greatest amount of info was the Marathon Motor Rep. Knew his stuff, and did a great job of explaining things. And of course, everyone here was mucho helpful too.

Rog


----------



## John Valdes (May 17, 2007)

varmit said:


> True, if you have drives on a network, however few places even require a contactor any more. Most drives, other than Seimens, do not have the capability for separate control power. I would normally only break the drive enable circuit through the E-stop. If the operator is using the E-stop, for a normal machine stop, someone needs some training. If there is a REAL need for an E-stop, faulting the network would be a minor problem.


I never use contactors on either the line or load side of the control. Sometimes the SOP for the facility will require the contactor. However, if they trust the installer/tech they will listen and allow just a disconnect ahead of the drive.

I do not like using the enable input either. If you are using braking it will coast instead of brake to stop. I use the stop input. That way I can control the stop.
Maybe the newer controls have addressed this issue. It has been 5 years since I have dealt with any controllers.


----------



## varmit (Apr 19, 2009)

John Valdes said:


> I never use contactors on either the line or load side of the control. Sometimes the SOP for the facility will require the contactor. However, if they trust the installer/tech they will listen and allow just a disconnect ahead of the drive.
> 
> I do not like using the enable input either. If you are using braking it will coast instead of brake to stop. I use the stop input. That way I can control the stop.
> Maybe the newer controls have addressed this issue. It has been 5 years since I have dealt with any controllers.




Yes, opening the enable loop will initiate a coast to stop and this can be a problem in some applications- some machine tools for example. I try not to have any absolute rules, just preferences for control logic. Most applications are unique and require a certain amount of customization for safe and efficient function.


----------



## VFDdistributing.com (Oct 19, 2009)

*We can help*

If you want to give us a call and explain the details of your application we will do what we can to have you up and running the RIGHT way.

thanks
Preston
Precision Electric
574-256-1000

http://www.precision-elec.com/


----------



## 5volts (Jan 11, 2008)

varmit said:


> As I stated previously, most of the newer drives will self protect against damage if there is a load loss (contactor opens) while running. It is mainly a problem with older versions.


Yeah, I realize you mentioned that already, but you also stated If you need/ are *required to have* a "e-stop" contactor, install it on the line side of the drive.

That will not work for some newer advanced applications and as far as dropping the enable is not a true E-stop in my oppinion. Relying on a "soft stop" AKA PLC logic is simply NOT SAFE.

Why not program a soft stop through the PLC and at the same time a "hardwire stop" to break the contactor? 

We keep our drives powered up with 12 VDC and break 480 v off the load side.

What do you think?


----------



## 5volts (Jan 11, 2008)

VFDdistributing.com said:


> If you want to give us a call and explain the details of your application we will do what we can to have you up and running the RIGHT way.
> 
> thanks
> Preston
> ...


AC Tech guy I hooked one of your drives and wired/configured it to a Allen Bradley control logix processor and it seemed like complete piece of garbage. Remember you are the guy that could'nt answer my question last time. When we decide to change drive manufactures we are going to go with ABB. We love those drives.


----------



## MDShunk (Jan 7, 2007)

p_logix said:


> AC Tech guy I hooked one of your drives and wired/configured it to a Allen Bradley control logix processor and it seemed like complete piece of garbage. Remember you are the guy that could'nt answer my question last time. When we decide to change drive manufactures we are going to go with ABB. We love those drives.


That's why I always liked using TB Wood's drives (they're Valcom now). When you call technical support, it's an actual product engineer from the plant that takes your call. It's the only made in the USA drive that I know about.

I also love ABB drives. I suppose I've used most major brands, and haven't run across any yet that I'd call "junk". If I'm in a pinch, I'll go to the supply house and get whatever brand they have in stock; usually a Square D drive, unless it's for a special application where I need some certain feature a certain drive brand might only have.


----------



## 5volts (Jan 11, 2008)

MDShunk said:


> That's why I always liked using TB Wood's drives (they're Valcom now). When you call technical support, it's an actual product engineer from the plant that takes your call. It's the only made in the USA drive that I know about.
> 
> I also love ABB drives. I suppose I've used most major brands, and haven't run across any yet that I'd call "junk". If I'm in a pinch, I'll go to the supply house and get whatever brand they have in stock; usually a Square D drive, unless it's for a special application where I need some certain feature a certain drive brand might only have.


MD, when you say your in a pinch what do you mean by that? Whatever they have in stock? Does that mean you have to get them up ASAP?


----------



## MDShunk (Jan 7, 2007)

p_logix said:


> MD, when you say your in a pinch what do you mean by that? Whatever they have in stock? Does that mean you have to get them up ASAP?


Uh-huh. Last one I needed in a hurry was, for of all things, for a fountain pump inside the lobby of a hotel. The customer's idea of an emergency does not always square with mine, but if they tell me it's urgent, I treat it as such. The drive ramped the pump up and down as lights in the fountain changed colors and such. It was sort of a dancing fountain. 

The one I recall most clearly needing in a hurry I actually had to get the supply house to unlock in the middle of the night. It was for some German made machine that made plastic Hawaiian leis 24/7. Must be a lot of money in plastic leis.


----------



## John Valdes (May 17, 2007)

p_logix said:


> AC Tech guy I hooked one of your drives and wired/configured it to a Allen Bradley control logix processor and it seemed like complete piece of garbage. Remember you are the guy that could'nt answer my question last time. When we decide to change drive manufactures we are going to go with ABB. We love those drives.


I prefer ABB over most, but I would not cut down this guys product. Everyone needs a line.



MDShunk said:


> That's why I always liked using TB Wood's drives (they're Valcom now). When you call technical support, it's an actual product engineer from the plant that takes your call. It's the only made in the USA drive that I know about.
> 
> I also love ABB drives. I suppose I've used most major brands, and haven't run across any yet that I'd call "junk". If I'm in a pinch, I'll go to the supply house and get whatever brand they have in stock; usually a Square D drive, unless it's for a special application where I need some certain feature a certain drive brand might only have.


Once you use a Magnetek, the only other drive you could use is ABB.
I liked the Baldor 18H control. I don't know if it is still available. It was the most user friendly along with the 15H.
Square D. I would drive a little further. But in a pinch?


----------



## Mountain Electrician (Jan 22, 2007)

John Valdes said:


> I prefer ABB over most, but I would not cut down this guys product. Everyone needs a line.
> 
> 
> 
> ...



I'm a huge fan of the Yaskawa G7 drives. Easy to set up and nearly bulletproof, at least compared to AB's Powerflex line. I believe Yaskawa and Magnetek are one and the same for around ten years now.


----------



## VFDdistributing.com (Oct 19, 2009)

p_logix said:


> AC Tech guy I hooked one of your drives and wired/configured it to a Allen Bradley control logix processor and it seemed like complete piece of garbage. Remember you are the guy that could'nt answer my question last time. When we decide to change drive manufactures we are going to go with ABB. We love those drives.


ABB isn't bad, i don't remember seeing your question though....


----------



## John Valdes (May 17, 2007)

Mountain Electrician said:


> I'm a huge fan of the Yaskawa G7 drives. Easy to set up and nearly bulletproof, at least compared to AB's Powerflex line. I believe Yaskawa and Magnetek are one and the same for around ten years now.


Yes, You are correct. :thumbsup: I think it's just Yaskawa now. Last I heard they were not building for anyone and had taken their name back and its all Yaskawa now. They were building for TECO and Magnetek among others. Like I said before I have not been doing much for the last 4-5 years.

Have you ever used Weg or Baldor? Weg builds some serious inexpensive controls with good quality. I reped Baldor, Weg, TECO, Yaskawa, Magnetek and ABB when I was in the motor and drive business. Baldor had a great drive 18H. It was a vector control and required a feedback device. That sucker really had the torque. 
Then the ABB torque control open loop was another good control. Baldor had a plain English programming scheme. I could teach anyone to program one if they could speak English.

That AC Tech drive looks like the Leeson drive inside and out. I have never used one before.


----------



## 5volts (Jan 11, 2008)

VFDdistributing.com said:


> ABB isn't bad, i don't remember seeing your question though....


Oh, 

it is right here but you will not get to open the thread because it was locked. Although you did leave a number which I never bothered to call. It just seems as if someone is coming here to this site to push a product and provide links they should at least know how to setup/configure the drive regardless of the communication method. If they don't its SPAM unless they are a sponsor to this site. 

VFDdistributing.com has just replied to a thread you have subscribed to entitled - VFD, Drive, Inverter Talk/Video

The topic can be found here:
http://www.electriciantalk.com/f2/vfd-drive-inverter-talk-video-9440-new-post/


----------



## Mountain Electrician (Jan 22, 2007)

John Valdes said:


> Yes, You are correct. :thumbsup: I think it's just Yaskawa now. Last I heard they were not building for anyone and had taken their name back and its all Yaskawa now. They were building for TECO and Magnetek among others. Like I said before I have not been doing much for the last 4-5 years.
> 
> Have you ever used Weg or Baldor? Weg builds some serious inexpensive controls with good quality. I reped Baldor, Weg, TECO, Yaskawa, Magnetek and ABB when I was in the motor and drive business. Baldor had a great drive 18H. It was a vector control and required a feedback device. That sucker really had the torque.
> Then the ABB torque control open loop was another good control. Baldor had a plain English programming scheme. I could teach anyone to program one if they could speak English.
> ...


I have a customer that uses almost exclusively WEG motors, but not the drives. They have a few different drives; Magnetek, AB 1336, AB Powerflex, SEW Eurodrive, Yaskawa and a couple of off brands I can't think of right now. Over the years, I've used Toshiba, and ABB as well, and would have to say I like Yaskawa the best. 

Yaskawa's modified constants file is a favorite feature of mine. It keeps any parameter you have changed from a factory setting in one place... very handy!


----------



## VFDdistributing.com (Oct 19, 2009)

p_logix said:


> Oh,
> 
> it is right here but you will not get to open the thread because it was locked. Although you did leave a number which I never bothered to call. It just seems as if someone is coming here to this site to push a product and provide links they should at least know how to setup/configure the drive regardless of the communication method. If they don't its SPAM unless they are a sponsor to this site.
> 
> ...


Ok, sorry about that, it would be hard to answer a question i cant see or hear though, Thats probably why i left a number. I'm really not trying to spam, i understand why it looks like that though. If you have a question I'll try to answer it... I do that all the time. I don't have a lot of experiences with other drives/inverters thats why i'm bringing up the SMV and AC tech products because thats what i know, i'm just trying to start interesting conversations about a product i know about.. not to argue, spam or upset anyone. I just thought maybe i could help you.


----------



## John Valdes (May 17, 2007)

Mountain Electrician said:


> I have a customer that uses almost exclusively WEG motors, but not the drives. They have a few different drives; Magnetek, AB 1336, AB Powerflex, SEW Eurodrive, Yaskawa and a couple of off brands I can't think of right now. Over the years, I've used Toshiba, and ABB as well, and would have to say I like Yaskawa the best.
> 
> Yaskawa's modified constants file is a favorite feature of mine. It keeps any parameter you have changed from a factory setting in one place... very handy!


Yes, I had a customer in the aggregate business that used Weg and Toshiba motors exclusively. They had to have heavy duty everything. They used Benshaw and ABB drives and switchgear. They would not even try anything else. They got it in their head that Benshaw and ABB were the only things that would hold up. Stubborn, rough folks.
Very particular customer for sure. But they had 100's of BIG motors. I was working for a motor shop at the time.


----------



## Safari (Jul 9, 2013)

MDShunk said:


> A VFD can often be a fantastic and cost saving option when running smaller 3-phase motors on a single phase service. The last one I did was for a second hand 3-phase Hobart dough mixer at a pizza shop. It was cheaper for me to install a VFD than it was to buy a phase converter for this machine. Changing the motor was not an option, since it's somewhat of a special motor for a dough mixer. I have a friend that has an old Bridgeport milling machine in his garage that he runs off a VFD also. He uses it for most of the speed control so that he doesn't have to mess with changing the belting around so much.


am literally scratching my head.in our company all the motors that we run on drives are three phase. meaning the input to the drive is three phase and direct to the three phase motor.smallest motor we have on drive is 5.5kw

now from your post above maybe i don't get it well. can you have a single phase input to a drive and power a three phase motor? if yes should you take into consideration the current? is this possible with all drives? mostly here we use ABB, micromaster,sinmatics(siemens),delta and yaskawa


----------



## BBQ (Nov 16, 2010)

nickson said:


> am literally scratching my head.in our company all the motors that we run on drives are three phase. meaning the input to the drive is three phase and direct to the three phase motor.smallest motor we have on drive is 5.5kw
> 
> now from your post above maybe i don't get it well. can you have a single phase input to a drive and power a three phase motor? if yes should you take into consideration the current? is this possible with all drives? mostly here we use ABB, micromaster,sinmatics(siemens),delta and yaskawa


The post you are responding to is three years old.

But to answer yes, most if not all drives can take a single phase input to drive a three phase motor. But you will not be able to use the drive to its full rating.


----------



## Safari (Jul 9, 2013)

BBQ said:


> The post you are responding to is three years old.
> 
> But to answer yes, most if not all drives can take a single phase input to drive a three phase motor. But you will not be able to use the drive to its full rating.


thanks so much BBQ.i didn't realize it was that old.appreciate .but it works with small motors only right?.can you provide where i can read alot about this


----------



## HARRY304E (Sep 15, 2010)

nickson said:


> thanks so much BBQ.i didn't realize it was that old.appreciate .but it works with small motors only right?.can you provide where i can read alot about this


http://www.plctalk.net/qanda/index.php

http://m.youtube.com/watch?autoplay...uri=%2Fwatch%3Fv%3DnS_0z0GSsFw%26autoplay%3D1

http://m.ecmweb.com/power-quality/basics-variable-frequency-drives


http://en.m.wikipedia.org/wiki/Variable-frequency_drive

.
.


----------



## JRaef (Mar 23, 2009)

nickson said:


> thanks so much BBQ.i didn't realize it was that old.appreciate .but it works with small motors only right?.can you provide where i can read alot about this


There are two basic rules for this that you must consider:

1) the drive must be *double* the HP rating of the motor you want to run*, or the corollary pointed out by Harry, you cannot use the drive at the full rating of the motor. The reason is twofold; the current through the input bridge rectifier increases by the square root of 3 (1.732x), but *also*, single phase rectification to DC has more ripple in the DC bus, and you need more capacitance to smooth it out. Using 2X sizing ensures that you get big enough capacitors so that they don't fail prematurely from being stressed. 

* Many small drives, 3HP and under at 230V are designed for single phase input without de-rating.

2) not ALL drives will allow this at all voltages. The reason is, some drives, especially 480V versions, are designed such that the internal control power is derived from power supplies connected to the incoming AC, so if you are missing one phase, something does not get powered and the drive doesn't function. The way to tell is, look at the manual and see if the drive has a "phase loss" trip function. If it does, then the next step is to see if there is a parameter you can set to disable that. If not, then you cannot use that drive to convert single phase to 3phase.

By the way I'm surprised to see that threads are not closed after a certain amount of time, most other forums do this. You can link to and reference older threads, but not respond to them.


----------



## HARRY304E (Sep 15, 2010)

JRaef said:


> There are two basic rules for this that you must consider:
> 
> 1) the drive must be *double* the HP rating of the motor you want to run*, or the corollary pointed out by Harry, you cannot use the drive at the full rating of the motor. The reason is twofold; the current through the input bridge rectifier increases by the square root of 3 (1.732x), but *also*, single phase rectification to DC has more ripple in the DC bus, and you need more capacitance to smooth it out. Using 2X sizing ensures that you get big enough capacitors so that they don't fail prematurely from being stressed.
> 
> ...


Top Dog..:thumbsup:


----------



## Safari (Jul 9, 2013)

JRaef said:


> There are two basic rules for this that you must consider:
> 
> 1) the drive must be *double* the HP rating of the motor you want to run*, or the corollary pointed out by Harry, you cannot use the drive at the full rating of the motor. The reason is twofold; the current through the input bridge rectifier increases by the square root of 3 (1.732x), but *also*, single phase rectification to DC has more ripple in the DC bus, and you need more capacitance to smooth it out. Using 2X sizing ensures that you get big enough capacitors so that they don't fail prematurely from being stressed.
> 
> * Many small drives, 3HP and under at 230V are designed for single phase input without de-rating.


jraef thanks alot for this info. i had to go through every manual of all the drives in our company and sure enough all the series that we have only allow three phase and any phase lose will issue an alarm.but it was great to know two things from you
1) a drive can be used as a phase converter.
2)the drive must be *double* the HP rating of the motor you want to


----------



## JRaef (Mar 23, 2009)

5volts said:


> AC Tech guy I hooked one of your drives and wired/configured it to a Allen Bradley control logix processor and it seemed like complete piece of garbage. Remember you are the guy that could'nt answer my question last time. When we decide to change drive manufactures we are going to go with ABB. We love those drives.


Just a point of reality check, if you are using a ControlLogix PLC there is no simpler interface on the market than making a PowerFlex VFD talk to a Logix PLC, they are literally plug and play. You need to speak to your local AB drives specialist.


----------



## Safari (Jul 9, 2013)

JRaef said:


> Just a point of reality check, if you are using a ControlLogix PLC there is no simpler interface on the market than making a PowerFlex VFD talk to a Logix PLC, they are literally plug and play. You need to speak to your local AB drives specialist.


jraef i have been looking at some of the old threads and responses to them and am learning alot.hey if u ever come for a safari to kenya,i will pay for the taxi ride around town just to say thanks for the input am getting


----------

