# Customer needs 30 Hp 3 phase Specialty compressor system.



## nownojin (Jan 12, 2015)

Ingersoll Rand 30-HP Tankless Rotary Screw Air Compressor (208V 3-Phase 125 PSI)

http://www.aircompressorsdirect.com/Ingersoll-Rand-UP6S-30-125-Air-Compressor/p61630.html

model ingersoll rand: up6s 30 125

A customer needs this 3 phase 30 hp compressor, It has a built in Xe-70m Programmable Controller
•Easily monitor operation on-site or by remote access
•Built-in event logging helps maximize efficiency & motor life

We have a single phase 120/240v 200A system at the location. I am Curious If we can use a VFD or phase converter to create 3 phase power for this particular piece of equipment or will it conflict with the built in controller. 

I do not know much about compressors , i am curious if we could find a similar single phase compressor ?

I need help selecting a VFD. Thank you for any help and suggestions!


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## micromind (Aug 11, 2007)

I wouldn't use a phase converter for this type of compressor. The reason being that the motors here are pretty 'high strung' meaning that they operate pretty close to their limits on normal POCO 3Ø power and any kind of phase converter will have too much voltage imbalance. 

A VFD would work but you might not get the full 60HZ out of it for the reason stated above. 

For 30HP, you'll need a 60HP VFD and make sure that it can operate on single phase. Most can, some cannot. 

You might need to change a parameter in the VFD to allow for single phase operation. 

The controls can be supplied with normal single phase power and the VFD will be controlled by the coil circuit of the mechanical starter. You'll need to substitute a relay for the existing starter since the VFD will most likely use 24DC for its start signal. 

If the existing starter is Y-∆, it might be a bit tricky to keep the fancy electronic controller from faulting on a starter failure. 

Also, depending on the configuration of the 200 amp service, getting a breaker big enough might be a problem.


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## Cl906um (Jul 21, 2012)

Are there other loads on this service? Kind of seems undersized to run that big of a motor load.


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## frenchelectrican (Mar 15, 2007)

nownojin said:


> Ingersoll Rand 30-HP Tankless Rotary Screw Air Compressor (208V 3-Phase 125 PSI)
> 
> http://www.aircompressorsdirect.com/Ingersoll-Rand-UP6S-30-125-Air-Compressor/p61630.html
> 
> ...



I wrote a underline one part .,, 

Sorry to be a bearer of bad news the 200 amp single phase service will not really handle 30 HP compressor at all because I do not know what other load you have in the exsting building.

Check with POCO to see if you can get Three phase supply in that location otherwise hevey up to 400 or 600 amp single phase if the POCO allow it. 

to run the VSD on single phase you will need to oversized the VSD at least 50% larger and not all the VSD units will not take single phase input at all.


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## Cl906um (Jul 21, 2012)

Is there three phase available?


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## Cl906um (Jul 21, 2012)

For that big of load, I would want a 200 amp three phase service for startup.


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## frenchelectrican (Mar 15, 2007)

Cl906um said:


> For that big of load, I would want a 200 amp three phase service for startup.


It may get by with that if the number of start and stop per hour is low. but I belive 400 amp service may suit better for that size of compressor unit.

Some POCO may have limitation of HP on their transfomers so check it ahead of time and you will need at least 75KVA is barebone minuim size to start up.


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## telsa (May 22, 2015)

Most Poco's have a 10hp limit for such monster start-up loads -- on single-phase Services.

The issue is the wicked voltage drop -- that infuriates the neighbors -- every time your motor kicks in.

The fact that you're using a VFD to generate 3-phase out of 1-phase does not eliminate this voltage sag issue.

The typical 1-phase distribution scheme is not wired for such start-ups.

The extreme example: our national atomic research labs with their bevetrons. They have specific deals that throttle back their induction loads... so that the master grid does not drop more than, say, 2%.

If they were to use "across-the-line" starters -- they'd crash the system -- for many states around. ( If such a critter could even be constructed. )


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## Flyingsod (Jul 11, 2013)

frenchelectrican said:


> It may get by with that if the number of start and stop per hour is low. but I belive 400 amp service may suit better for that size of compressor unit.
> 
> Some POCO may have limitation of HP on their transfomers so check it ahead of time and you will need at least 75KVA is barebone minuim size to start up.


I'd feel perfectly comfortable putting that on a 3ph 200 amp service. Assuming an inverse time circuit breaker or time delay fuses at the feeder. A SINGLE phase service...not so much.
To OP, it might be doable depending on the drive you get with some advanced programming. Honestly though if you are not well versed in drive and motor theory (in which case you wouldn't have to be asking) you will have to hire an expert to engineer and program your set up. 50 percent derating is not really enough except in situations where your motor is not going to rub at full load. A compressor at times will be running at full load. 40 percent is closer to an actual derating and at 40 percent you are Prolly hitting right at that 200amp mark. I'm thinking it's not worth the risk... if anything else is on that service forget it.

To Frenchelectrician, he mentioned it's a screw compressor. They run 100 percent of the time and utilize an unloading valve to regulate pressure. The start/stop cycle for them is typically once a day. The start stop cycle is so often ignored, its cool that you mentioned it.

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## frenchelectrican (Mar 15, 2007)

Flyingsod said:


> I'd feel perfectly comfortable putting that on a 3ph 200 amp service. Assuming an inverse time circuit breaker or time delay fuses at the feeder. A SINGLE phase service...not so much.



True and I know with three phase 208 system it can take large as 30 HP without issue the bottom line is the POCO transformer size that can change a bit. if it was used in lateral services for sure no question asked 75 KVA is ready and common item .,, but overhead cans or pigs that is kinda toss up depending on what POCO do with their pigs .,, but yes they can sling up 75 KVA pigs 


Flyingsod said:


> To OP, it might be doable depending on the drive you get with some advanced programming. Honestly though if you are not well versed in drive and motor theory (in which case you wouldn't have to be asking) you will have to hire an expert to engineer and program your set up. 50 percent derating is not really enough except in situations where your motor is not going to rub at full load. A compressor at times will be running at full load. 40 percent is closer to an actual derating and at 40 percent you are Prolly hitting right at that 200amp mark. I'm thinking it's not worth the risk... if anything else is on that service forget it.


I agree with him on this one and ya have to do the load demand caluation to see where ya standing on exsting loads plus add it up on compressor load and see where the number adds up. 



Flyingsod said:


> To Frenchelectrician, he mentioned it's a screw compressor. They run 100 percent of the time and utilize an unloading valve to regulate pressure. The start/stop cycle for them is typically once a day. The start stop cycle is so often ignored, its cool that you mentioned it.


Yep no problem at all and I am aware of screw compressor type useally run most case 

To OP ;

You may have to change over to three phase service but barebone minium is 200 amp 208 volt service or add a 200 amp 480 volt three phase service so you can add more machinery from this service. and keep the exsting single phase service if POCO allow it otherwise get a transfomer to downstep for single phase loads


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## Southeast Power (Jan 18, 2009)

nownojin said:


> Ingersoll Rand 30-HP Tankless Rotary Screw Air Compressor (208V 3-Phase 125 PSI)
> 
> http://www.aircompressorsdirect.com/Ingersoll-Rand-UP6S-30-125-Air-Compressor/p61630.html
> 
> ...


If it were me, I would get hold of the compressor rep and let them know what your demand is and the power you have available. I know for a fact that you are not the only one with this problem.
On another note, a 30 Hp screw drive is a fancy piece of equipment.
If he bought it surplus and wants you to connect it, it's time to spend the money he saved on a heavy up.


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## nownojin (Jan 12, 2015)

Thank you everyone for the input. Basically the only load i know of is this 30 hp compressor. The customer is promising more equipment. I have requested specs several times. I am going to tell them to give me specs/nameplates of all current equipment and possible future equipment. So i can do a load calc and plan review and get the poco involved i have a feeling i need a 400-600 amp 3 phase system.


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## Ty the electric guy (Feb 16, 2014)

I installed a 10Hp screw compressor a few months ago and realized that it didn't start under load. Nameplate said 10Hp at 240v but I've never seen it draw over 35 amps. I'm not very familiar with screw compressors but I don't think they are high inertia like normal compressors. 


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## Southeast Power (Jan 18, 2009)

Ty the electric guy said:


> I installed a 10Hp screw compressor a few months ago and realized that it didn't start under load. Nameplate said 10Hp at 240v but I've never seen it draw over 35 amps. I'm not very familiar with screw compressors but I don't think they are high inertia like normal compressors.
> 
> 
> Sent from my iPhone using Tapatalk


That's about right for 10hp.
Put it on a 60, hope it doesn't draw 40. 

Does the output go through a dryer? 

I was thinking that the OP would need another 20 amps for that.


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## Cl906um (Jul 21, 2012)

frenchelectrican said:


> It may get by with that if the number of start and stop per hour is low. but I belive 400 amp service may suit better for that size of compressor unit.
> 
> Some POCO may have limitation of HP on their transfomers so check it ahead of time and you will need at least 75KVA is barebone minuim size to start up.


Thanks for the backup. I wouldn't consider that big of a load on single phase 240. Never got an answer if three phase were available. Too tight a budget it seems.


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## Cl906um (Jul 21, 2012)

Even with a drive, you still have a hard time tricking startup current. It can be lowered but it does it by speed. Compressors have torque.


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## micromind (Aug 11, 2007)

Ty the electric guy said:


> I installed a 10Hp screw compressor a few months ago and realized that it didn't start under load. Nameplate said 10Hp at 240v but I've never seen it draw over 35 amps. I'm not very familiar with screw compressors but I don't think they are high inertia like normal compressors.
> 
> 
> Sent from my iPhone using Tapatalk


Every screw compressor I've ever installed starts unloaded. It there is pressure at the screw discharge, it'd turn backward, there'd be no oil and it'd seize up pretty quickly. 

The vast majority of self-contained units I've hooked up use Y-∆ starting. This results in a starting current of roughly 1/3 of the normal starting current and a starting torque of roughly 1/3 or a bit less of normal starting torque. 

Most of these units keep the compressor pump intake blocked off during starting then open it when the starter switches from Y to ∆. 

A VFD will easily start a pump like this but it could take a bit of programming to get it in the run position.


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## JRaef (Mar 23, 2009)

You cannot use a VFD unless you completely separate the control circuits and the motor circuits, so that the VFD is ONLY feeding the motor. That would be trickey even for an experienced controls person plus it would likely void any warranty (if this is new). In addition I looked up the specs on it, this is a splash lube type system, so you may have issues on starting it with a VFD because you may need to get it to full speed very quickly. That might require even MORE over sizing of the drive. You really need to engage IR for help on this.


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## Cl906um (Jul 21, 2012)

You may be able to get by cheaper by just putting in another service, like a grounded b delta that you could put right by the other one if three phase is available. Different type so usually you can have more than one on the same building.


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## Southeast Power (Jan 18, 2009)

Cl906um said:


> You may be able to get by cheaper by just putting in another service, like a grounded b delta that you could put right by the other one if three phase is available. Different type so usually you can have more than one on the same building.


That's all good if they have a second phase available.


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## micromind (Aug 11, 2007)

Changing a single phase service to a 240∆ or a 208Y is not all that difficult. Often, all that needs to be done is change the meter base, the panel (sometimes just the interior) and add another wire. 

If it's overhead, it's likely 2" already and if the mast is straight, shoving another wire down it is easy. If it's underground, it's the POCOs problem.


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## JRaef (Mar 23, 2009)

micromind said:


> Changing a single phase service to a 240∆ or a 208Y is not all that difficult. Often, all that needs to be done is change the meter base, the panel (sometimes just the interior) and add another wire.
> 
> If it's overhead, it's likely 2" already and if the mast is straight, shoving another wire down it is easy. If it's underground, it's the POCOs problem.


In some places that's true, in other places it's not that easy. It's not that uncommon for PoCos to use a SWER (Single Wire Earth Return) system to save money on running power to users that will only need single phase. Or they will run a phase and a neutral rather than two phases, because they will reduce the size of the neutral to save money. In either of those cases if you ask for even an open delta 3 phase drop, they will make you pay for running the extra wire out from the nearest true three phase connection, then they ding you for the cost of the transformers.


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## Southeast Power (Jan 18, 2009)

micromind said:


> Changing a single phase service to a 240∆ or a 208Y is not all that difficult. Often, all that needs to be done is change the meter base, the panel (sometimes just the interior) and add another wire.
> 
> If it's overhead, it's likely 2" already and if the mast is straight, shoving another wire down it is easy. If it's underground, it's the POCOs problem.


I think people would prefer a WYE system but can only get a Delta due to the POCO not wanting to bring in a 3rd phase. 
They would have to set a third pig too.


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## Corysan (Jan 20, 2017)

Using a VFD for a power source is bad practice. In this case, the compressor already has a VFD to drive the prime mover. You would probably experience significant problems with the conflicting carrier frequencies of the two VFD's, not to mention problems associated with using the replicated AC waveform of the VFD powering the electronic controller. This is probably why JRaef recommended separating control power.

If your customer is only operating with 200A at 120/240 V single phase, their power consumption is not that great. The main reason for using screw compressors is for energy savings. I would discuss this situation with your customer's Ingersoll Rand representative and ask him why he is recommending this piece of equipment. It seems to me that they would most likely not do that at all. Screw compressors are high ticket items, and the I-R rep's I have dealt with always make a site visit to confirm power availability in order to specify the compressor to meet the customer's needs. I am pretty sure that someone cannot buy a compressor like this new without I-R's help. If your customer bought one on the used market, that a the sign that this customer is somewhat short-sighted.

What is your customers reasoning for the installation? Your realistic options are four-fold. You can either have a second service of the appropriate voltage system installed. All of his current 240 V equipment will function adequately at 208 V single phase. You could recommend them finding a building with the appropriate power. You could recommend against the purchase of this compressor; and if they need more volume, solve the problem by installing an additional piston compressor in parallel with the existing compressor which feeds into a holding tank. You will need the help of someone with a fair amount of experience in pneumatics for this. You could back off altogether and protect yourself from liability.


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## Corysan (Jan 20, 2017)

It is easy to lose sight of the long term implications of working with "good" customers. There are times when helping to solve a customer's self-imposed technical problems only work against you. I have dealt with this kind of situation, where someone absolutely has to install a piece of equipment, and is not willing to invest adequately in the infrastructure to make it work properly. In this case, the purchase of a screw compressor to provide air to a small shop (200A 120/240V?) is like buying a Case Magnum tractor to plow a backyard garden because it will save time. I do not see this ending well.


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## Southeast Power (Jan 18, 2009)

Corysan said:


> It is easy to lose sight of the long term implications of working with "good" customers. There are times when helping to solve a customer's self-imposed technical problems only work against you. I have dealt with this kind of situation, where someone absolutely has to install a piece of equipment, and is not willing to invest adequately in the infrastructure to make it work properly. In this case, the purchase of a screw compressor to provide air to a small shop (200A 120/240V?) is like buying a Case Magnum tractor to plow a backyard garden because it will save time. I do not see this ending well.


I think it either fell off of the back of a truck or the shop owner shops on Ebay after a few Drinks.


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## JRaef (Mar 23, 2009)

Corysan said:


> ... In this case, the compressor already has a VFD to drive the prime mover. ...


I looked at the data sheets, I didn't see that. Other than that, I agree with everything else you said. A VFD is not meant to be a power source for an entire system, it is ONLY for running a 3 phase motor.


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## Corysan (Jan 20, 2017)

> I looked at the data sheets, I didn't see that.


Thanks for pointing that out. I did not initially look at the spec.'s. I am not a compressor expert, but I have not yet seen a screw compressor without a VFD. You gave me pause to consider, though. I looked at the spec.'s and they showed it to be belt driven, which raised an eyebrow. They did not state that the controller was not a VFD, however. I tried to cross reference the model number from the sales website to I-R's website with no luck. The closest I could come was I-R advertising some compressors as VSD compressors. This is not conclusive, but certainly allows for other control means. Point well taken, it pays to look at the details and be specific.

That said, I have concerns about the proposed installation concerning necessity. How did the customer arrive at the conclusion that this was the compressor for them? Pneumatic system applications are very analogous to electrical system applications. More is better, but too much is still too much. It is very common now to forego the expense of expert advice from an engineer when designing electrical systems and the EC is used instead to save cost. This is often adequate, but not always and problems result. Even the EC (hopefully) approaches the system based on current customer needs (which includes equipment purchased but not yet installed) and projected future demands. How does this customer know his volume requirements?


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