Hanbell RE-1050A

[Calders]

Anyone with good knowledge of Hanbell RE screw compressors out there?
I have 2 questions.
1) During commissioning we have found that the compressors fail to fully unload after shut down via SV1 25% solenoid. Unloading while running is no problem. The discharge pressure easily returns the capacity slide piston when the compressor is running and SV1 is energised.
My concern is that an emergency shut down could result in compressor not being unloaded at next start up. This has been witnessed on this site.
2) 1x new compressor is constantly loading up even with SV2 load solenoid disconnected. SV2 solenoid was inspected and found to be in new condition. When you energise SV1 the compressor unloads to 25% but as soon as you close SV1 the compressor loads up again. I suspect oil to be by-passing into the slide cylinder, maybe via a faulty gasket but I have little knowledge of Hanbell Screws.
If anyone has any info or a rebuild manual it would be greatly appreciated.
Thanks in advance.

[RANGER1]

Calders,
Here is a bit of information, will look for more later.

http://www.hanbell-vn.com/upload/20425_re-cnn.pdf

[Calders]

RANGER1 Thanks for the response and link.
The link gives an in-depth description of the loading operation but I need to know what's inside this lump. I suppose I'm hoping for an easily accessible failed gasket that I can simply replace to cure the constant loading problem.
With regard to the compressors not fully unloading via SV1 25% solenoid when the compressor is shut down I wonder if this is common to the Hanbell RE compressor. On all other manufacturers screw compressors I have worked on the capacity slide piston spring is man enough to return the capacity 25%.
Thanks all for looking. Really appreciate it.

[RANGER1]

RANGER1 Thanks for the response and link.
The link gives an in-depth description of the loading operation but I need to know what's inside this lump. I suppose I'm hoping for an easily accessible failed gasket that I can simply replace to cure the constant loading problem.
With regard to the compressors not fully unloading via SV1 25% solenoid when the compressor is shut down I wonder if this is common to the Hanbell RE compressor. On all other manufacturers screw compressors I have worked on the capacity slide piston spring is man enough to return the capacity 25%.
Thanks all for looking. Really appreciate it.

Calders,
Check your email, not exact manual, but will give you a good idea.
Easiest to replace solenoids & check capillary.
Assume oil filter cleaned & check for metal.
Oil temperature not to cold as troubleshooting suggests.
Next would be check unload cylinder & spring, if spring weak etc, then could be an issue.

If you were to contact Hanbell or agent, I would think they would help, give them serial number , Model etc.

Good luck
Manual shows tool to insert unload piston seal if it comes to that.

[Calders]

Thanks again RANGER1: Compressors are RE-1050A. The design is a bit different to the RC model.
I have 4 of 4 new compressors that don't unload fully when shut down which leads me to think its a compressor design issue. Oil was replaced along with internal oil strainer. Oil is just warm, discharge only runs at about 43DegC so maybe the oil is a bit too viscus at this temperature.
As you suggest I think a weak spring or maybe cylinder seals are tight on these new compressors.
Only 1 of the 4 has the constantly loading up issue, however that compressor replaced another that went bang after only 23hrs run time so there is a possibility of some contamination from previous failure.
Its great to start hammering out ideas - You really have me thinking about oil temperature now because I was surprised how cool this machine ran (Discharge superheat is fine by the way).

[RANGER1]

Thanks again RANGER1: Compressors are RE-1050A. The design is a bit different to the RC model.
I have 4 of 4 new compressors that don't unload fully when shut down which leads me to think its a compressor design issue. Oil was replaced along with internal oil strainer. Oil is just warm, discharge only runs at about 43DegC so maybe the oil is a bit too viscus at this temperature.
As you suggest I think a weak spring or maybe cylinder seals are tight on these new compressors.
Only 1 of the 4 has the constantly loading up issue, however that compressor replaced another that went bang after only 23hrs run time so there is a possibility of some contamination from previous failure.
Its great to start hammering out ideas - You really have me thinking about oil temperature now because I was surprised how cool this machine ran (Discharge superheat is fine by the way).

If they are new, under warranty, I would refer back to Hanbell.

Can you advise on refrigerant type, oil cooling if any, running conditions?
Normally oil temperature has to be 10-15 deg C above saturated condensing pressure, otherwise oil can be saturated with refrigerant, meaning poor lubrication.
I don't think any oil cooling or liquid injection should be on under cool conditions.



Although not same model, here is a YouTube video

Micro Control Systems Hanbell Piston Changeout mpeg - YouTube

Reasonably basic machine, refer to manual or Hanbell about oil & temperatures.

[Calders]

Refrigerant R513A
Chilled water on/off 13/8 DegC.
Condensing water on/off 29/34 DegC.
Condensing at around 33 DegC, discharge superheat 14degC
Evaporating at around 4 DegC, suction superheat 6 degC.
Discharge temperature 47 to 55 DegC depending on capacity.
No economiser fitted, no liquid injection or any other oil cooling.
Oil type: all compressors were factory charged with Hanbell HBR-B04 but we did an oil change on one with an equivalent oil which was Solest 220.

constantly loading fault has somehow rectified itself.?????
But unloading while stopped is still an issue. Basically we can not get these compressors to reliably unload when stopped.
I am sure its a compressor/oil issue and we are waiting for further info from Hanbell.

[RANGER1]

Calders,
The unloading issue, do you have a LPI or slide valve position indicator?
Does it have step, or step less capacity control.
Normal stop, is it unloaded already before shut down.

What is the solenoid control sequence on start/stop, as instructions indicate unload before stopping for 60-90 seconds.
Unload before start for 1-3 minutes before starting.

Not sure how many solenoids you have, or what control method, as there are several.
Some solenoids can be NO, or NC type, so unless identified will be confusing.
On page 7 of first link, maybe you have this, but a NO solenoid?

[Calders]

Hi again Ranger,
No position indicator on this compressor.
Step less control with 25%,50% & 100% solenoids.
Original control was terrible - The 25% energised for 30 seconds before start up and remained energised for further 30 once running. After that modulation control between 50 - 100%. Original normal operation was shutdown at 50% and not as per manual.
It looks like the chiller manufacturer was trying to avoid running below 50% to negate the need for auxiliary cooling. However this application does not overheat at 25% so we linked the 25 & 50% outputs and disconnected the 50% solenoid to now give fully modulating step less control.
Normal operation is now shut down at 25%. But if the building remote management switches off the chillers then the compressors would have likely stopped in a loaded position so we added a further hard wire modification.
Solenoids are all NC and work fine. When compressor is running the unloading and capacity control is great.
So no mistake with solenoids.
The manufacturer of the chiller has not designed the control strategy as per Hanbell manual this I am very aware. However we have done all sorts of fixes to keep 25% solenoid energised when compressor is off, Delayed BMS remote off for 90 seconds and energising 25% solenoids during this delay period.
So control is now pretty much as Hanbell recommend.
My problem remains - If for any reason the compressors stop at a capacity above 25%, the compressors don't reliably unload regardless of how long the 25% solenoid is energised before that start.
I am sure the problem is with Hanbell. For some reason the slide spring is unable to reliably return the slide piston to the 25% position when the compressor is not running and the 25% port (SV1) is open.
The chiller manufacturer is in discussions with Hanbell but we don't seem to be getting anywhere.
I'll update you if we get an answer.

[RANGER1]

Hi again Ranger,
No position indicator on this compressor.
Step less control with 25%,50% & 100% solenoids.
Original control was terrible - The 25% energised for 30 seconds before start up and remained energised for further 30 once running. After that modulation control between 50 - 100%. Original normal operation was shutdown at 50% and not as per manual.
It looks like the chiller manufacturer was trying to avoid running below 50% to negate the need for auxiliary cooling. However this application does not overheat at 25% so we linked the 25 & 50% outputs and disconnected the 50% solenoid to now give fully modulating step less control.
Normal operation is now shut down at 25%. But if the building remote management switches off the chillers then the compressors would have likely stopped in a loaded position so we added a further hard wire modification.
Solenoids are all NC and work fine. When compressor is running the unloading and capacity control is great.
So no mistake with solenoids.
The manufacturer of the chiller has not designed the control strategy as per Hanbell manual this I am very aware. However we have done all sorts of fixes to keep 25% solenoid energised when compressor is off, Delayed BMS remote off for 90 seconds and energising 25% solenoids during this delay period.
So control is now pretty much as Hanbell recommend.
My problem remains - If for any reason the compressors stop at a capacity above 25%, the compressors don't reliably unload regardless of how long the 25% solenoid is energised before that start.
I am sure the problem is with Hanbell. For some reason the slide spring is unable to reliably return the slide piston to the 25% position when the compressor is not running and the 25% port (SV1) is open.
The chiller manufacturer is in discussions with Hanbell but we don't seem to be getting anywhere.
I'll update you if we get an answer.

Calders,
Thanks for feedback on your issue, will wait for your response from Hanbell
Out of interest, how do you know compressor is not unloading when off, do you have hard start, or trips on overload?

[Calders]

For a good start the line and star contactor pull in, compressor quickly builds up to full speed and the transition to delta about 3 seconds later is very smooth. Inrush current is as expected for star-delta and current draw remains stable and low (120A per phase) for the next 30 seconds while 25% solenoid is energised
I have witnessed a few hard starts and when I know the compressor was stopped at load. Inrush is above 1000A (greater than I can record with my meter). The compressor almost stalls in star and has hard transition to delta. The initial running current has been up to 160A then reduces to 120A during the first 30 seconds while the 25% solenoid is energised and the compressor unloads.
During testing I have had a number of starts like this and I generally reach for the emergency stop before the transition to Delta. Leaving the 25% solenoid energised overnight results in a good start the following day.