# I don’t have a rotation meter :(



## Cow

Is it a rotary screw compressor?


Does it have a vfd on the motor?


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## canbug

Being direct drive may make this harder but does a compressor really care which direction it's turning? You need to see the shaft to determine direction or go pick yourself up that rotation meter you've been wanting.


Tim.


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## MechanicalDVR

canbug said:


> *Being direct drive may make this harder but does a compressor really care which direction it's turning?* You need to see the shaft to determine direction or go pick yourself up that rotation meter you've been wanting.
> 
> 
> Tim.


YES, especially a screw type compressor.

If you ran even a tiny residential type backwards you'd know the noise it makes a block away.


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## five.five-six

canbug said:


> Being direct drive may make this harder but does a compressor really care which direction it's turning? You need to see the shaft to determine direction or go pick yourself up that rotation meter you've been wanting.
> 
> 
> Tim.


I’m more concerned about damaging it. Most motors runs just fine backwards, it’s the things connected to the mother that may have some trouble in reverse. 


Not sure if there’s a VFD on it, I didn’t see anything I recognize as a VDS but it’s german (I think) so they my use a funny looking VFD


If my wholesale house has a rotation meter in stock, and it’s not too much then I’ll pick one up just cuz I’m always looking for an excuse to buy a new tool


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## canbug

My home compressor is single phase so I haven't heard that ugly noise.


Tim.


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## five.five-six

MechanicalDVR said:


> If you ran even a tiny residential type backwards you'd know the noise it makes a block away.


How is it that you know this?

Hmmm



By “YES” does that mean it will break the compressor?


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## JoeSparky

A day late and a dollar short for this, but you can own cheapo Chinese phase meter for under twenty bucks from Amazon or ebay.


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## splatz

Get a T+ Pro and review the phase rotation function here when you're done.


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## MechanicalDVR

five.five-six said:


> How is it that you know this?
> 
> Hmmm
> 
> 
> 
> By “YES” does that mean it will break the compressor?



HVAC/R was a large part of what I worked with for years. One of the family businesses I worked in as a youngster was a mechanical contracting business.

"Mechanical DiVeR"

I've worked for two very large electro-mechanical contractors where we were factory service on more than one brand of HVAC equipment. AAON, Mammoth, Dry-o-tron being some of them (military, schools, hospitals, municipal facilities).

On large jobs I was often already on the job when there was a breakdown and being that type equipment is 95% electrical/electronic and or control issues I'd often be the one to find and fix the problem. I always had a good assortment of fuses, relays, contactors, starters, and capacitors on my van. 

Doing that type of control work I always carried individual gauges to adjust set points on pressure controllers and that type of thing as well.

Depending on the running pressures of the refrigerant used and the type of screw (contacting or non contacting vanes) yes you can damage the screw mechanism.


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## five.five-six

So, If I can’t get a rotation meter, should I wait to energize the compressor?

Customer is a machine shop and most of his machines require compressed air and are down at the moment


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## MechanicalDVR

five.five-six said:


> So, If I can’t get a rotation meter, should I wait to energize the compressor?
> 
> Customer is a machine shop and most of his machines require compressed air and are down at the moment


Can you borrow a rotation meter?


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## sbrn33

Why would you do the start up on a large compressor?


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## oliquir

Bring a small motor to test rotation if you have no rotation meter


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## five.five-six

My supply house doesn’t have one in stock, 

Walters retail electric does have one 

I’ll get one there.


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## telsa

I've hooked up such compressors -- and like H I'd be responsible for rotation. 

I simply told the customer -- get the HVAC boys out here to fire this puppy up.

"I left A (black) and C (blue) only nominally tight... so you can flop them easily. (for rotation) Be sure to really snug them down when you go final."

Of course the Kaeser crew came back and fired it up. it's part of their contract.

Even a rotary-screw compressor can take a few seconds of reverse. But the noise tells the tech all that he needs to know. So he cuts it off. 

&&&&

I don't think that Kaeser makes anything but rotary-screw compressors.

&&&&

For those curious, the original technology was used to compress carbon dioxide in vast amounts to inject into oil fields. The units were monsters. The scheme was to drill for carbon dioxide, pipe it over, and then compress it even further to inject into the ground. Then the gas would drive even more oil to the surface. As time went by, the units became ever smaller, and more to a general purpose. The first beasts were astoundingly expensive. Only Big Oil could afford them.

If their machining wasn't so expensive, rotary-screw compressors would be even more common. They put recip compressors to shame.


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## Flyingsod

*I don’t have a rotation meter [emoji20]*

Fwiw at this point you cannot look at another motor to determine rotation of a different motor unless:
1. It’s the same brand
2 it’s the same model
3 it was made in the same plant
4 it was made in the same production run
5 it was wired by the same tech
6 it was a consistent tech. 

In other words just don’t rely on it. 
I’m sure things are more procedural and codified these days but it’s still not a safe bet. 

I’ve no experience with that brand but my last company had an entire air comp division and I wired up plenty of screws. It was fine to bump them for rotation. One finger on start one on stop, hit stop as quick as you can and watch the coast down for rotation not the start, someone else watching the rotation if you can’t get a good view. Rely on arrows to tell you what’s right do NOT go by sound or common sense. The arrow is your cya device. GL


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## Flyingsod

oliquir said:


> Bring a small motor to test rotation if you have no rotation meter




Not trustworthy enough as I outlined below. Sure it works sometimes but in no way is it 100%. And with high dollar items that you are morally responsible for it’s not worth the risk. 


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## glen1971

Can it be uncoupled for a test run? It may take some time, and an additional cost, but then you know for sure which way it is running. Most places I've been won't bump motors coupled, and will have a millwright to uncouple it. There are a few exceptions we've ran coupled to check rotation, with the largest being cooling fans. 
Being the guy that had to sit down and explain to a client why their air compressor piled up after we did some MCC work because the guy I had on those cubicles assumed they were wired up "Red, Black, Blue", when they weren't is not a fun place to be.
It isn't worth it, to chance it. And to using another motor, as @Flyingsod said, I wouldn't trust it. Too many variables. 

A shot in the dark, does it have a phase reversal relay wired in from the factory at the control panel? Some do, and they won't engage the controls unless the rotation is correct.


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## CoolWill

A rotary screw will survive a bump to check rotation. I wouldn't run it for any real amount of time, but just half a second or so should be enough.


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## Southeast Power

You should get one of these today:

DLG DI-PT01 Non-contact Phase Rotation Tester










its $59 on Amazon, Prime delivery tomorrow.

The bigger one is $145 

Extech Non-Contact Phase Sequence Tester - PRT200


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## gpop

glen1971 said:


> Can it be uncoupled for a test run? It may take some time, and an additional cost, but then you know for sure which way it is running. Most places I've been won't bump motors coupled, and will have a millwright to uncouple it. There are a few exceptions we've ran coupled to check rotation, with the largest being cooling fans.
> Being the guy that had to sit down and explain to a client why their air compressor piled up after we did some MCC work because the guy I had on those cubicles assumed they were wired up "Red, Black, Blue", when they weren't is not a fun place to be.
> It isn't worth it, to chance it. And to using another motor, as @Flyingsod said, I wouldn't trust it. Too many variables.
> 
> A shot in the dark, does it have a phase reversal relay wired in from the factory at the control panel? Some do, and they won't engage the controls unless the rotation is correct.


Everyone ive wired had a idiot relay (phase reversal protection). At 75hp it should be belt drive so thats a 10 minute job to drop the belts just to be on the safe side.


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## Flyingsod

*I don’t have a rotation meter *

Been thinking about this today and I can’t think how this would tell you 100% what direction the motor is going to turn. The phase rotation meter will only tell you if the incoming phases will give you ccw or cw if hooked up in order. This is no guarantee that Hooking your new motor up phase abc to leads 123 will give you the same rotation. Again it might work out that way a great majority of the time but motor techs can and do get the leads criss crossed. 

The only time in a couple decades as a service tech I used the shops rotation meter in the field was to assure that no matter which receptacle a machine was plugged into the phasing would remain the same. It wasn’t feasible to move this machine a dozen times just for testing. The phase rotation meter was useful in that situation. 

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## gpop

Flyingsod said:


> Been thinking about this today and I can’t think how this would tell you 100% what direction the motor is going to turn. The phase rotation meter will only tell you if the incoming phases will give you ccw or cw if hooked up in order. This is no guarantee that Hooking your new motor up phase abc to leads 123 will give you the same rotation. Again it might work out that way a great majority of the time but motor techs can and do get the leads criss crossed.
> 
> The only time in a couple decades as a service tech I used the shops rotation meter in the field was to assure that no matter which receptacle a machine was plugged into the phasing would remain the same. It wasn’t feasible to move this machine a dozen times just for testing. The phase rotation meter was useful in that situation.
> 
> Sent from my iPhone using Tapatalk


They make a rotation meter that you clip to the bottom of the starter then get someone to spin the motor by hand in the right direction (i normally wrap a rope around the shaft and pull on it but you can just as easily remove the fan cover). That will tell you which way its wired.
Then simply do a live test to get the direction of the incoming power.


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## Southeast Power

I haven’t used one as intended but I have accidentally burned one up:

https://www.greenlee.com/us/en/phase-sequence-motor-rotation-meter


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## MTW

Southeast Power said:


> I haven’t used one as intended but I have accidentally burned one up:
> 
> https://www.greenlee.com/us/en/phase-sequence-motor-rotation-meter


I blame that on NewElect85.


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## Southeast Power

MTW said:


> I blame that on NewElect85.


That’s part of the story.
The kit comes with both meters.
I wrote “not this one” on the motor rotation tester so he wouldn’t get hurt or burn it up.
Fortunately, it was a 208 volt circuit I checked with the motor tester.
That’s the day I ordered the contactless testers for everyone.
I really recommend replacing whatever you are using with the contactless type.
It could have been much worse for me using that meter on a hot circuit. Some of them explode.


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## Flyingsod

gpop said:


> They make a rotation meter that you clip to the bottom of the starter then get someone to spin the motor by hand in the right direction (i normally wrap a rope around the shaft and pull on it but you can just as easily remove the fan cover). That will tell you which way its wired.
> 
> Then simply do a live test to get the direction of the incoming power.




Nice, I was musing about the possibility of such a device. Now I don’t have to think about it anymore thanks


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## Switched

If you were closer, I would have let you borrow one of the three I have.


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## 460 Delta

telsa said:


> I've hooked up such compressors -- and like H I'd be responsible for rotation.
> 
> I simply told the customer -- get the HVAC boys out here to fire this puppy up.
> 
> "I left A (black) and C (blue) only nominally tight... so you can flop them easily. (for rotation) Be sure to really snug them down when you go final."
> 
> Of course the Kaeser crew came back and fired it up. it's part of their contract.
> 
> Even a rotary-screw compressor can take a few seconds of reverse. But the noise tells the tech all that he needs to know. So he cuts it off.
> 
> &&&&
> 
> I don't think that Kaeser makes anything but rotary-screw compressors.
> 
> &&&&
> 
> For those curious, the original technology was used to compress carbon dioxide in vast amounts to inject into oil fields. The units were monsters. The scheme was to drill for carbon dioxide, pipe it over, and then compress it even further to inject into the ground. Then the gas would drive even more oil to the surface. As time went by, the units became ever smaller, and more to a general purpose. The first beasts were astoundingly expensive. Only Big Oil could afford them.
> 
> If their machining wasn't so expensive, rotary-screw compressors would be even more common. They put recip compressors to shame.


While what you say about efficient is true, screws lose a large amount of oil out the air-oil separator and without a really good secondary oil removal system put large amount oil into the air. Not good for many apps at all. 
Drill for CO2? that's a new one for me, natural gas yes but never heard of underground CO2 reserves, please elaborate.


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## splatz

460 Delta said:


> Drill for CO2? that's a new one for me, natural gas yes but never heard of underground CO2 reserves, please elaborate.


I never heard of it either but I am interested in this kind of thing since fracking became a very big deal. I found this 

https://www.netl.doe.gov/sites/default/files/netl-file/CO2_EOR_Primer.pdf


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## CoolWill

460 Delta said:


> While what you say about efficient is true, screws lose a large amount of oil out the air-oil separator and without a really good secondary oil removal system put large amount oil into the air. Not good for many apps at all.
> Drill for CO2? that's a new one for me, natural gas yes but never heard of underground CO2 reserves, please elaborate.



He said to inject into oilfields, as in enhanced oil recovery, EOR. DuckDuckGo it.


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## five.five-six

OK

I’m an idiot, it was 25 HP, not 75 HP

I did buy an ideal and it works for both power and checking motor (so I don’t have to stencil it “not this one”)

I really hate Walters retail electric $200 for that thing. Turns out CED bought them and I like CED

The screw I wired up had piss poor documentation, it was used and some of it was missing but it did state that it has a safety circuit that would shut it down if rotation was reverse.

It came up just fine.

Just don’t get me started one the *@#$!!! 90 degree sealtight connector I used to get into the compressor!!! I really hate that thing 


Also, for everyone who contributed to the thread, thanks for all the help. There is a wealth of experience that I have learned from without actually screwing it up myself


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## glen1971

460 Delta said:


> Drill for CO2? that's a new one for me, natural gas yes but never heard of underground CO2 reserves, please elaborate.


Some gas wells produce carbon dioxide from their formations.


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## telsa

Screw compressors can tolerate liquid in their discharge.

Recips can't.

Carbon dioxide can easily be compressed all the way to liquid.

The oil field scheme would've been to compress it as a gas -- pretty hot -- and then chill it to a liquid as it flows down hole so as to pressurize oil out.

In this the scheme is almost identical to water-flood which everyone knows about.

The carbon dioxide scheme only pencilled out where the gas was close by and water was not to hand. Carbon dioxide is a superior injectable, BTW. It really lubes the crude. Whereas oil and water don't mix.

The fact that the early machines let oil into the compressed gas stream was irrelevant to the oil industry.


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## glen1971

On a tangent, CO2 is also captured and stored underground..
https://www.jwnenergy.com/article/2...ig-co2-storage-milestone-costs-trending-down/


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## Kevin

Flyingsod said:


> Been thinking about this today and I can’t think how this would tell you 100% what direction the motor is going to turn. The phase rotation meter will only tell you if the incoming phases will give you ccw or cw if hooked up in order. This is no guarantee that Hooking your new motor up phase abc to leads 123 will give you the same rotation. Again it might work out that way a great majority of the time but motor techs can and do get the leads criss crossed.
> 
> The only time in a couple decades as a service tech I used the shops rotation meter in the field was to assure that no matter which receptacle a machine was plugged into the phasing would remain the same. It wasn’t feasible to move this machine a dozen times just for testing. The phase rotation meter was useful in that situation.
> 
> Sent from my iPhone using Tapatalk


Amprobe makes a phase rotation meter that you can place on top of a motor and it will tell you which way it spins. I never got to see it used in person.

https://www.transcat.ca/amprobe-prm-6-prm-6-225550

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## catsparky1

If you run a Keaser compressor backwards you WILL blow the diaphragm out . 
I know this and it costs just shy of 500 to fix .


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## 460 Delta

telsa said:


> Screw compressors can tolerate liquid in their discharge.
> 
> Recips can't.
> 
> Well that isn't really true, I've personally slowly poured alcohol in a compressor intake [piston comp] while running to melt a ice plug in a down stream line. It works, I've done it.


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## glen1971

460 Delta said:


> telsa said:
> 
> 
> 
> Screw compressors can tolerate liquid in their discharge.
> 
> Recips can't.
> 
> Well that isn't really true, I've personally slowly poured alcohol in a compressor intake [piston comp] while running to melt a ice plug in a down stream line. It works, I've done it.
> 
> 
> 
> With enough liquid in the suction side of a recip and your mechanics will send you Christmas cards... Why not inject downstream of the compressor?
Click to expand...


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## QMED

Kevin_Essiambre said:


> Amprobe makes a phase rotation meter that you can place on top of a motor and it will tell you which way it spins. I never got to see it used in person.
> 
> https://www.transcat.ca/amprobe-prm-6-prm-6-225550
> 
> Sent from my Samsung using Tapatalk


Yes this thing is awesome. $100 on Amazon though


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## 460 Delta

​


glen1971 said:


> 460 Delta said:
> 
> 
> 
> With enough liquid in the suction side of a recip and your mechanics will send you Christmas cards... Why not inject downstream of the compressor?
> 
> 
> 
> Well an alcohol injector is just another thing to leak air out of. The alcohol in the intake trick is saved only for have to situations not every day. The heat of the compressor makes it into a mist that hits a ice plug and melts it usually pretty quick. Most of the operations have winter day end shut down procedures that get the water out of the lines and valves, occasionally however things simply just happen.
Click to expand...


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## joebanana

flyingsod said:


> not trustworthy enough as i outlined below. Sure it works sometimes but in no way is it 100%. And with high dollar items that you are *monetarily* responsible for it’s not worth the risk.
> 
> 
> Sent from my iphone using tapatalk



fify


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## Kevin

QMED said:


> Yes this thing is awesome. $100 on Amazon though


I just pulled up the first link I found. I saw it for 100$ on Amazon Canada. 

My last company had one. They paid like 160$. I didn't get to use it though 

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