Three Phase Compressor

[joeslad]

Will A 3 Phase Compressor Run Ok In Both Directions?

[frank]

It depends on the type of compressor.

[joeslad]

Yea ok,will have to check that. It ran ok ,possibly a bit noisy! but the temperature was dropping.

[Abe]

A Scroll can only run in one direction

A recriprocating can be run in either..........
But look at the oil glass, if oil is squishing about, foaming...then change phases

This is what Ive been told....
I await a "qualified" view

[joeslad]

Cheers aiyub. Lang may u lum reek.

[mark375]

Hi
This is my first post, I have been looking in on this forum for some time and finally feel I have something to add.

Screw compressors don't work with the incorrect DOR, or at least not for long. Recip's can run but the oil pump probably only works correctly in one direction.

Normally if the DOR is critical it will be marked somewhere.

[chemi-cool]

All compressors, apart from scrolls can turn to both directions.

On some of the open ones, there is a rotating direction, marked with an arrow.


Chemi

[joeslad]

Thanks. Pardon my ignorance though, but how can you tell which way a compressor is running?

[chemi-cool]

You can't.

Only on open ones.

Chemi

[frank]

Thanks. Pardon my ignorance though, but how can you tell which way a compressor is running?

When commissioning a system and checking for refrigerating effect it is normal to have service gauges connected.
The gauges will show high and low side pressures. If you connect gauges to a scroll compressor running the "wrong" way then you do not see any compression taking place and therefore, no refrigerating effect.

On a recip compresor you will see compression taking place no matter which way the compressor is running

[US Iceman]

As someone said earlier, Screw compressors should only be operated in one direction! They are not bi-directional.

The manufacturers will have a direction of rotation arrow provided on the compressor. Open drive screw compressors should have the coupling taken apart for the pre-start direction check. With this method you are only checking the motor direction, not the compressor.

After the correct direction has been verified, install the center member in the drive coupling.

Most open drive reciprocating compressors will operate in either direction. The manufacturer may have a preference due to the belts.

[Argus]

The only compressor that will run in either direction is a recip without an oil pump. Even then, some larger recips have uni-directional oil pumps and on those the direction is important.

Screws, Scrolls, Centrifugals and Rotary are all designed to operate in one direction only.

If it is critical - there will be an arrow.

If all else fails, read the instructions.
________
Chevrolet pickup truck

[Temprite]

A lot of the milk vats around this neck of the woods have Terry open drive compressors

PJS or VS

They can run both ways but there is a recommended rotation direction. From what I have heard it uses a dipper connected to crankshaft which picks up oil, If operated in reverse it doesnt pick up enough oil.

[Cofreth]

Again how do you defined the rotation is correct or not correct for a refrigerant cooled screw compressor?
As mentioned from above types of compressor like scroll,screw,centrifugal etc. can they afford to be rotate the oppose direction just for a rotation test?Will it damage to any internal mechanical parts or gear?

[chemi-cool]

In some, there is internal clutch, some will make noise but no suction.
Thats how. It will not damage them if you check it in the first start.

Chemi

[US Iceman]

A screw compressor can be used to generate power if gas is expanded through it backwards.

True... If you are using the compressor as an expander.


But...The screw packages have check valves on them, which prevent reverse gas flow!

On any open drive screw compressor, the motor should be uncoupled from the compressor for the rotation test to prevent damage.

From what I have heard it uses a dipper connected to crankshaft which picks up oil, If operated in reverse it doesn't pick up enough oil.

This type of lubrication is called a splash-type. The dippers are the only means of lubrication.

Other compressors that have an oil pump are forced lubrication and have internal oil passages drilled in the crankshaft and connecting rods to allow oil flow. Also required for shaft seals in open drive compressors.

The semi-hermetic reciprocating compressors (Copeland, Caryle, and Bitzer, I think) do not have any required direction of rotation. The oil pumps are reversible.

[US Iceman]

Joeslad,

how can you tell which way a compressor is running?

I have been trying to remember how to check for direction of rotation in 3-phase systems using an electrical check.

Amprobe used to make an add-on adapter that was called a phase sequence adapter. This was used to verify the direction of rotation on the Dunham-Bush vertical screw compressors.

I found some other ideas in the links below:
http://www.engineeringtalk.co.uk/news/flu/flu183.html

http://www.fluke.com.sg/sgen/product...FlukeSingapore

http://www.fluke.co.uk/comx/pubs.asp...stit-t1&page=1

http://www.testsell.co.uk/displaypro...ence+Detectors

There are probably more, but this should give you a good start.

[malik55]

On new machines where rotation is crtical such as screws, scrolls and centrifugals a phase sequence device is used in the control circuit and it will not allow the machine to come on line if rotation is not correct.
Cofreth, yes the compressor may damage due to a wrong direction, some manufacturers says not to jog the machine even for to check the rotation, the phase sequence must be checked before to connect the power supply.

[Abe]

Is it possible that members can post pictures of "screw compressors" in situ

Im not really wanting to see manufacturers type, brochure pictures, but actual live models all set up that you probably have worked on , and taken a snap shot of.

Only reason I ask, this thread has developed quite nicely and with it the technical aspects discussed has accordingly advanced.

For those of us, who dont normally get on hands on the bigger stuff, it would be enormously helpful to see pictures.

Thx

[chillin out]

Abe,

For those of us, who dont normally get on hands on the bigger stuff, it would be enormously helpful to see pictures.

Come out with me tomorrow and you can do all my calls. I am knackered, been working all day and now I have to go back out again.

But yes I will try to get some pics.

[Peter_1]

Recip's can run but the oil pump probably only works correctly in one direction.

There is a very simple but special system build in an oilpump so that it can run in both directions.

[mark375]

There is a very simple but special system build in an oilpump so that it can run in both directions.

Not if it is a gear type pump driven from the crankshaft.

[US Iceman]

Aiyub,

Here are some pictures from a project I worked on. These were installed in a large chemical plant. These are operating with R-22.

Picture number 6 is a large propane screw compressor package going into the paint booth. I did not have pictures of this installed, but it is an impressive picture.

[wambat]

1. There is no negative impact on durability caused by operating three phase Scroll compressors in the reversed direction for a short period of time. However, after several minutes of operation the compressor’s internal protector will trip. Reverse operation for over one hour may have a negative impact on the bearings.
2. Screw compressors may only be operated in one direction of rotation otherwise substantial mechanical damage will occur.
• Connect a compound gauge to the suction service valve,
fully front seat the suction service valve and then open one full turn.
• Bump start the compressor - switch on then
off quickly (approximately 0.5 to 1 second).
If the direction of rotation is correct the suction
pressure will drop immediately.

[vaidas_78]

Bitzer screws.Bitzer.jpg

Bitzer1.jpg

[US Iceman]

Hi Guys,

I went surfing for additional information on the reversible oil pump issue.

http://www.carlylecompressor.com/PDFs/06D06E/06de_2.pdf

http://www.copeland-corp.com/america...us/oilpump.htm

http://www.bitzer.de/document/doc.php?DCODE=KP-525
(see page 3 in the PDF)

All of these have reversible oil pumps.

[Abe]

Iceman.. Vaidas

Thank you, great pictures...........

[US Iceman]

Aiyub,

Your welcome.

I'm happy I could find some to post for your review.

[adacus1]

'Most' three phase reciprocating compressors have a reversible oil pump such that the compressor can be operated in either direction without detriment to the compressor.

Scroll compressors only work in a single direction which can be seen when you attach a gauge set, if rotating correctly you will have normal suction and discharge pressures but if running in reverse there is little or no difference between suction and discharge pressures.

Screw compressors only operate in a single direction and when a gauge set is attached will likely show a small reversal of suction and discharge pressures if running in reverse. This happens because the screw compressor is a positive displacement type pump and a certain amount of refrigerant will be moved backwards through the system if the compressor is backwards. How much depends on the system design and what checks are in place in the overall system.

Compressor manufacturers build compressors for standard ISO rotation RST and you should use a phase rotation meter to verify the phase connections prior to installing, then install as per the compressor manufacturers instructions for phase rotation.

Will A 3 Phase Compressor Run Ok In Both Directions?

[adacus1]

Carlyle 06D and 06E compressors for R134a have a crankshaft driven gear oil pump which is reversible the same as the vane toil pumps originally installed for R12/R22

Not if it is a gear type pump driven from the crankshaft.

[US Iceman]

But... not if the screw package is being used to generate power

Yes, but... If the twin screw is designed as a refrigeration compressor, the thrust bearings are on the wrong end of the compressor.

When a twin screw is used as an expander, the flow through the compressor is reversed. This transfers the axial bearing load to the opposite end of the compressor.

I believe the check valves would still be required on expansion service, since the expander would still probably back-spin during shutdown.

In theory, I completely agree with you. In practice, if the compressor is built for compression service the compressor should not be ran backwards for expansion.

[Steve Wright]

Not all recips are birotational, phase conection determines rotation and if it is rotation sensitive the Operation Manual will tell you.

Most recips less than 25HP are not rotation sensitive.

Steve

[chemi-cool]

Hi Steve.

I have changed through the year, a few 60 hp Trane compressors.
Nothing about rotation.
Please enlighten me, how can one tell the direction of rotation in semi hermetics?

Chemi

[Steve Wright]

Chemi

How is this for a late answer.

The rotation sensitive recip commpressors that I've seen were old open types that were Trane or Carrier maybe Worthington. These were like older than me and I'm 55. I belive the issue was non reversing the oil pump.

I can't think of any new or newly remans that rotation is an issue.

I don't know how you would tell the rotation on a semi however you would check for proper rotation (if required) with a phase sequence meter.

I think its cheap insurance to check.

So sorry for the super late response

Steve