# First VFD



## retiredsparktech (Mar 8, 2011)

Honestly said:


> I come from a residential and light commercial background, and for the first time have the need to install a VFD. Application is a 3ph 50hp irrigation pump. This is the only 3ph piece of equip, so I advised the customer that a VFD would be cheaper than changing his single ph service to 3 ph.
> 
> Can anybody recommend a good company to buy from, that would have good customer support to help me select the VFD that I need and also be there to answer questions if I have any?


I don't think they make a single phase VFD for that large of a motor.


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## JRaef (Mar 23, 2009)

Honestly said:


> I come from a residential and light commercial background, and for the first time have the need to install a VFD. Application is a 3ph 50hp irrigation pump. This is the only 3ph piece of equip, so I advised the customer that a VFD would be cheaper than changing his single ph service to 3 ph.
> 
> Can anybody recommend a good company to buy from, that would have good customer support to help me select the VFD that I need and also be there to answer questions if I have any?


Ooooh, a virgin! :w00t:

Down boys, down boys...

First, you need to understand that to power a 50HP motor from a single phase resource, the VFD must be TWICE the size of the motor, so you will need a 100HP drive. This is because the line input components of the drive must be capable of the SINGLE PHASE current draw, which is higher than the 3phase motor current by a factor of 1.732 (the square root of 3). Then because a single phase rectifier will create more DC ripple on the bus, which the transistors can't live with, you need more capacitance on the DC bus, which is why the VFD size is doubled.

Next, you must remember that the Code requires that your conductors feeding the VFD must be sized at 125% of the *VFD's* maximum input amp rating, not the motor's. So you must look at the max input amps of tht 100HP drive to size the conductors, even though the motor is only 50HP.

Then you must make sure that you either use RGC for the raceways, or use what is called "VFD cable" that is shielded, and ground the shields at BOTH ends, not just one like in signal wiring.

Lastly, if the motor is not "inverter rated", you should use motor output filters to prevent insulation damage and bearing destruction. I always recommend input line reactors as well, they help to protect what will be a very expensive drive.


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## John Valdes (May 17, 2007)

VFD's in the smaller sizes can be fed with single phase even though they are three phase VFD's.
But retired is correct that a 50 hp application is to large for this.

OP. Be very careful here. Do not suggest this yet as it is most likely not going to happen. 
I have been out of the loop for a few years now. But when I was in the loop, there was no VFD that could handle this application.
The single phase input to the 3 phase VFD is for small VFD's in the fractional to around 5 HP with no derating.
Larger applications where derating is required would most likely make this out of the question.

Call any drive supplier and ask them. Do you use a motor shop or PT house? Call them and explain what you have.
I seriously doubt a VFD is going to be an option.


I suggest you find another way to do this. A VFD is not the answer to this problem you have.


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## don_resqcapt19 (Jul 18, 2010)

John Valdes said:


> ...I suggest you find another way to do this. A VFD is not the answer to this problem you have.


I am not so sure about that....it might very well be the most cost effective solution. I know that Yaskawa says that all of their drives are suitable for use with a single phase source at a 50% derating. 

Of course, as Jeff said, you need enough power to drive the motor from the existing single phase service. If the service cannot support the load, then changing the service to 3 phase might be more cost effective.


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## JRaef (Mar 23, 2009)

John Valdes said:


> VFD's in the smaller sizes can be fed with single phase even though they are three phase VFD's.
> But retired is correct that a 50 hp application is to large for this.
> 
> OP. Be very careful here. Do not suggest this yet as it is most likely not going to happen.
> ...


Actually, it is done quite a bit in far flung rural irrigation applications because the utility must run 2 more wires out to a remote pole where there is just a single pump. What the utility usually does is run a SWER at 10-15kV or so out to a pole and plop a single transformer on it to give them single phase power, often 480V single phase to keep the transformer size down. If the nearest 3 phase connection point is 5 miles away, the cost to have them run 2 more conductors that far, add cross beams to all of the poles and install another transformer is extremely high, in the neighborhood of $35,000 in some cases I have worked on.

So yes, the packaged NEMA 3R VFD will cost $15K+, but the difference can still be very significant.

As to brands, one important aspect is that not all brands can be fed with single phase power even if de-rated, because they sense a phase loss and their trip function cannot be defeated. So you have to check the manual for any drive you select to make sure it can be made to be OK with a single phase source BEFORE you purchase it. 

And by the way if the service is already dropped and it is 240V single phase, your choices for 100HP 240V VFDs become limited. I see that Mitsubishi and Hitachi both offer 100HP 230V drives, but I did not check to see if they can accept 1 phase input. To the earlier point, the input current rating is around 270A, so if your service drop is only 200A, it isn't going to work. Hopefully you do not already have the service drop and you can ask the utility to give you 480V single phase, because the VFD will cost you less and as I mentioned, that is very common on rural irrigation systems.

The best brand in my opinion is the one that you can get the best LOCAL support on. I happen to like the A-B PowerFlex 400 for this and I know it is OK with a single phase input, but they only go that high in 480V, they stop at 50HP at 240V. Admittedly though, they sign my paycheck every month so I have a slight bias... :innocent:


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## tates1882 (Sep 3, 2010)

Does the pump actually need to change speed? If not the a rpc and across the line starting maybe the cheapest way or a single phase motor.


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## Honestly (Feb 3, 2011)

JRaef said:


> Ooooh, a virgin! :w00t:
> 
> Down boys, down boys...
> 
> ...


Great info, thanks. I knew about the derating, but not the shielded cable or output filters.


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## John Valdes (May 17, 2007)

tates1882 said:


> Does the pump actually need to change speed? If not the a rpc and across the line starting maybe the cheapest way or a single phase motor.


This was my actual point.
Doubling the size of the VFD and all the other things Jraef mentioned were the reason why I did not think it would be cost effective.
But it is possible to do.
Most anything is possible to do.
You could run 4/0 to a 120 volt 15 amp receptacle if you wanted, but you would not do it.

Don, Yes, of course it can be done. I have used more than one drive sharing one buss to operate one motor on several occasions. So, I am familiar with how to use and derate these controls.
Cost was my biggest concern and still is.


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## Honestly (Feb 3, 2011)

I have not been out to the site yet, so I don't know the size of the existing service, other than being single phase. Sounds like I will just need to price it both ways (service change or VFD). I know that he has been using a rpc for years, but said he had had problems with it. It may be that something was not sized properly or installed correctly to begin with. I will check it out on site in the few days and get more info from the customer.

Thanks for the responses.


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## John Valdes (May 17, 2007)

Honestly said:


> Great info, thanks. I knew about the derating, but not the shielded cable or output filters.


The line side IMO is the first place to put your money.
Long distances from loads require load side filtering, but not all drive output loads require filtering. Or reactors as some might call them.


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## tates1882 (Sep 3, 2010)

I'm not a vfd expert but why couldn't you put a filter after the rcp and add a drive. You may have to defeat some factory parameters so the drive will accept the manufactured leg but the filter should help ease the process.


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## xlink (Mar 12, 2012)

tates1882 said:


> Does the pump actually need to change speed? If not the a rpc and across the line starting maybe the cheapest way or a single phase motor.


Consider a rotary or static phase converter.


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## SteveBayshore (Apr 7, 2013)

I have installed pump stations in urd developments with single phase primary distribution, the POCO has never complained about dropping two padmount transformers and supplying a 3 phase delta service. The way l read the original question, the installation did not require a drive, he suggested it as an alternate method. A 50 hp soft start would be swell.


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## JRaef (Mar 23, 2009)

Honestly said:


> I have not been out to the site yet, so I don't know the size of the existing service, other than being single phase. Sounds like I will just need to price it both ways (service change or VFD). I know that he has been using a rpc for years, but said he had had problems with it. It may be that something was not sized properly or installed correctly to begin with. I will check it out on site in the few days and get more info from the customer.
> 
> Thanks for the responses.


Just so we can all gain from the experience, let us know what the utility quotes for upgrading him to a 3phase drop and roughly how far it was to the nearest connection.

By the way, maybe the pump is not using variable speed now because he does not have it, but chances are he could benefit greatly from adding that capability. Variable speed pumping for irrigation systems, depending on the type, can be used to avoid spillage and other forms of water waste, match well recovery rates and /or match pressure requirements. All of those can result in lower energy use, and in some cases if it is well documented, the utility will contribute to the equipment cost in the form of rebates. That may be worth checking into Honestly.


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## Honestly (Feb 3, 2011)

Oh.


Wow.


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## Honestly (Feb 3, 2011)

....


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## Honestly (Feb 3, 2011)

Hp is 50 on that first motor, 25 on the other (which he said is just a backup)


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## xlink (Mar 12, 2012)

I think the instructions on a static phase converter say the motor HP has to be derated by 1/3. Is it similar on a rotary converter?


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## Cow (Jan 16, 2008)

I like that control panel:whistling2: It looks like the ones I have to work in over here....

I see a lot demo'ing in your future!


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## dronai (Apr 11, 2011)

I installed a rotary phase convertor for a new 25hp 3 phase pump. Never had any problems

What's wrong with the set up he has now ? How long does that pump run at a time ?

Edit- " I know that he has been using a rpc for years, but said he had had problems with it. It may be that something was not sized properly or installed correctly to begin with."


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## Jlarson (Jun 28, 2009)

Yeah, we deal with similar messes all the time. I strongly push for a new 3 phase service. Less maintenance and complications down the line.


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## swimmer (Mar 19, 2011)

tates1882 said:


> I'm not a vfd expert but why couldn't you put a filter after the rcp and add a drive. You may have to defeat some factory parameters so the drive will accept the manufactured leg but the filter should help ease the process.


Tates,
Do you mean really rcp or rpc as in Rotary Phase Converter?

Never mind. Dronai answered it.


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## HARRY304E (Sep 15, 2010)

swimmer said:


> Tates,
> Do you mean really rcp or rpc as in Rotary Phase Converter?
> 
> Never mind. Dronai answered it.


Thanks for Bumping the tread,,,It's a good one..:thumbup:


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## Honestly (Feb 3, 2011)

I am looking at this project again... The only things fed from this service are the two pump motors (and controls), and a single service receptacle and overhead light. What type and voltage service would you go with? (Assuming poco would deliver whatever)


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## SteveBayshore (Apr 7, 2013)

If there is only a single phase primary distribution circuit(two phase legs), try to get a 120/240 volt, three phase, delta service. If there is a a three phase primary distribution circuit, a 277/480 volt service would be better (1/2 the amperage) if your pumps are dual voltage. If you only have a single primary conductor and a ground or static conductor, I think you'll be stuck with the single phase service that you have.


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## Honestly (Feb 3, 2011)

SteveBayshore said:


> If there is only a single phase primary distribution circuit(two phase legs), try to get a 120/240 volt, three phase, delta service. If there is a a three phase primary distribution circuit, a 277/480 volt service would be better (1/2 the amperage) if your pumps are dual voltage. If you only have a single primary conductor and a ground or static conductor, I think you'll be stuck with the single phase service that you have.


I know three phase is available, but I have rarely dealt with 480, so I did not know if there were any benefits other than smaller conductors. Everything is contained in a 10x12 pump house, so there would not any long runs. And 480 would necessitate me getting a transformer for the service receptacle. Sorry for all the questions, but commercial services supplying motors is new territory for me.


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## LATTC (Feb 12, 2012)

JRaef said:


> Actually, it is done quite a bit in far flung rural irrigation applications because the utility must run 2 more wires out to a remote pole where there is just a single pump. What the utility usually does is run a SWER at 10-15kV or so out to a pole and plop a single transformer on it to give them single phase power, often 480V single phase to keep the transformer size down. If the nearest 3 phase connection point is 5 miles away, the cost to have them run 2 more conductors that far, add cross beams to all of the poles and install another transformer is extremely high, in the neighborhood of $35,000 in some cases I have worked on.
> 
> So yes, the packaged NEMA 3R VFD will cost $15K+, but the difference can still be very significant.
> 
> ...


Would it not be better to just up size the RPC? How long will that VFD last? 

If I'm installing, I would up size the RPC, setup a better control method and safe that farmer some money.

How about Written-Pole® motor?


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## sam-the-electrician (Jul 21, 2013)

*You can contact Franklin Empire ==> http://www.feinc.com/*

You can contact Franklin Empire http://www.feinc.com/. They can help you




Honestly said:


> I come from a residential and light commercial background, and for the first time have the need to install a VFD. Application is a 3ph 50hp irrigation pump. This is the only 3ph piece of equip, so I advised the customer that a VFD would be cheaper than changing his single ph service to 3 ph.
> 
> Can anybody recommend a good company to buy from, that would have good customer support to help me select the VFD that I need and also be there to answer questions if I have any?


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## circuitman1 (Mar 14, 2013)

if ya need more amps ,i would up size the converter like one of the other guys said , a bigger line for 3 phase is going to cost.unless a bunch of other customers will benefit. if ya go withe 3 phase anyways,a 5kva should be sufficent for just a light & receptacle.:thumbup:


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