copeland scroll durability

[Third_techtrio]

I need some help about the durability of this Copeland scroll compressors. We replaced our old copeland reciprocating compressors with these new Copeland Scroll compressor as per recommendation by the supplier because this new compressor is more energy efficient and there is no more available copeland recip in the market. The problem is that, out of 5 compressor we have replaced 2 of them are already defective, because of this busted ASTP (Advanced Scroll Thermal Protector) that supposed to protect the compressor. When it automatically suspend the compressor pumping due to high head temperature and after letting it cool for a day, this ASTP never reset back and the compressor never got back its pumping action even though its motor runs continuously. Just want to know from refrigeration Guru's out there if they have encountered something like it and any recommendation, especially other brand of compressor. By the way, the compressor model is ZR94.

[desA]

Just how high did the discharge temperature go?

Please supply your refrigerant & operating conditions, so that we can better assist you.

Does sound pretty unusual, as these compressors are usually pretty solid.

[monkey spanners]

I've fitted a few copeland scrolls to replace thier obselete recip compressors and haven't had any trouble with them.
maybe the problem is the high discharge temps they had been running with.

I have also fitted L'unite/Techumseh compressors in place of Copelands where price was more of an issue.

[Third_techtrio]

I never actually have the chance to acquire the discharged pressure/temperature of the unit but our post finding of one of the system that we have just replaced last couple of months ago with new compressor with the astp(advanced scroll temp protector) was that the liquid line filter-drier was partially restricted that may ave cause the high head pressure/temperature. My concern is that this thermal protector on mechanical side of the compressor should have reset to normal after the compressor have cooled down.

[tonyhavcr]

]I never actually have the chance to acquire the discharged pressure/temperature[/B] of the unit but our post finding of one of the system that we have just replaced last couple of months ago with new compressor with the astp(advanced scroll temp protector) was that the liquid line filter-drier was partially restricted that may ave cause the high head pressure/temperature. My concern is that this thermal protector on mechanical side of the compressor should have reset to normal after the compressor have cooled down.

Not a dig BUT how do you replace a compressor with-out acquire the discharged pressure/temperature of the unit?

(My concern is that this thermal protector on mechanical side of the compressor should have reset to normal after the compressor have cooled down.)

Yea so it should reset - Why did it open !

[desA]

Yea so it should reset - Why did it open !

A point to add:

How many times did the thermal overload have to open/close before the technicians were called out to the site?

Was this a once-off occurrence, or did it happen many times?

[Third_techtrio]

Yeah, the cut-off of astp occurred just once. I did not have the chance to test-run the unit because its astp did not reset.

[jessica050129]

I think the high discharge temperature would be the reason for the failure. I remembered that I used a temperature switch on the discharge pipe extra to control the discharge temperature. and the default was 115 Centigrade.

[desA]

I think the high discharge temperature would be the reason for the failure. I remembered that I used a temperature switch on the discharge pipe extra to control the discharge temperature. and the default was 115 Centigrade.

Can I ask where the figure of 115'C comes from?

Copeland data sheets call for an upper continuous operating discharge temp limit of 107'C.

[DEVIL]

Just my point of view

Wat is the compressor used for ?
Dose the hight pressure protection work (or dose it have one) ?
If the compressor overheated and the protection opened for several times without being noticed it might blown the winding (lucks like a open protection) ?
Is the unit is having a over-current (edit - protection )?
if it is having one, did you set it for the new specs of the compressor ?

Tons of question and not a lot of info

[azahedi]

imhave the same problem here with scroll copeland ZR12-M3. I think these compressors are so sensitive to operation conditions. I think my compressor is lost due to late consideration, and ofcourse I think the same thing about yours. This would be a mechanical failure caz in my compressor electric tests show nothing wrong. The compressor operates with a bad noise and without compression. anyway i have found a reciprocating copeland and wanna go back to that kind of comp. any ideas?
thanks.

[DEVIL]

(as my post before) For someone to judge your situation correct we need the entire data , what is it used for is it a water-air heat pump, water-water heat pump, air conditioning, refrigeration, all are different cases, and then how it behaves, did someone do any work in it, or it's the first failure (and it's like the factory made it .)

If your compressor make noise it might got some debris from past work on it, or it might got flooded with liquid and killed the valves.

We need info for the answer to be correct.
And a scroll is more efficient and more reliable if it's installed correct and all the conditions are like the factory requested.

[azahedi]

(as my post before) For someone to judge your situation correct we need the entire data , what is it used for is it a water-air heat pump, water-water heat pump, air conditioning, refrigeration, all are different cases, and then how it behaves, did someone do any work in it, or it's the first failure (and it's like the factory made it .)

If your compressor make noise it might got some debris from past work on it, or it might got flooded with liquid and killed the valves.

We need info for the answer to be correct.
And a scroll is more efficient and more reliable if it's installed correct and all the conditions are like the factory requested.


I have used ZR12 for high cycle of a cascade system where the lower point of the high cycle is about -30:-25 C using R22. I think this kind of scroll has no internal protection but an external CAREL Motor protection which should be actuated by lines to operate. This protection was not active and the last operation of the compressor was a pump down to fix a
valve leakage. after the reparation, The compressor did not start. actually its rotor runs and electrical tests show resular amperage and voltage for all phases but I have no compression. Today I separated the compressor from cycle and checked it out of it but already no compression.
I have another scroll ZR72 which has internal protection instead of the CAREl one in ZR12. the ZR12 just behaves like when ZR72(6 HP) does in case of thermal overload. but for a so longer time than 30 min. of ZR72.
As time is an important factor for me I think I should decide soon. and I am suspecious about using another ZR12! maybe I should use QR12 which is a Recip. Hermaetic copeland product. I really don`t know.

[girirath]

have you got hp cutout which will avoid astp to open

[coolhibby1875]

this compressor should have a discharge klixon that straps to the pipe to cut out the compressor if discharge temp gets to high, you should also look at your h/p saftey switch settings!

[VRVIII]

I need some help about the durability of this Copeland scroll compressors. We replaced our old copeland reciprocating compressors with these new Copeland Scroll compressor as per recommendation by the supplier because this new compressor is more energy efficient and there is no more available copeland recip in the market. The problem is that, out of 5 compressor we have replaced 2 of them are already defective, because of this busted ASTP (Advanced Scroll Thermal Protector) that supposed to protect the compressor. When it automatically suspend the compressor pumping due to high head temperature and after letting it cool for a day, this ASTP never reset back and the compressor never got back its pumping action even though its motor runs continuously. Just want to know from refrigeration Guru's out there if they have encountered something like it and any recommendation, especially other brand of compressor. By the way, the compressor model is ZR94.


I never actually have the chance to acquire the discharged pressure/temperature of the unit but our post finding of one of the system that we have just replaced last couple of months ago with new compressor with the astp(advanced scroll temp protector) was that the liquid line filter-drier was partially restricted that may ave cause the high head pressure/temperature. My concern is that this thermal protector on mechanical side of the compressor should have reset to normal after the compressor have cooled down.

Hi,

Why would anyone replace compressors without replacing driers, fitting LP switches or fully testing it? This is only asking for trouble.

I would say that the thermal protector (bi metal disc) has reset but the compressor has been damaged due to excessive overheating. The compressor oil will break down under these conditions, thermal expansion of the scroll would wear the scroll tips, thrust faces and damage bearings. New compressor required.

These compressors have 3 protection devices:
1/ line break thermal protector imbedded into motor windings (protect windings)
2/ scroll discharge protection device, the compressor control circuit must be wired across terminals M1 M2. Did you connect this safety device?
3/ bi metal disk that will allow bypass when scrolls overheat. The bypass would then cause a rapid increase in discharge temp, causing the protection device to trip. But was this connected?

However all of the above will also take time to react and would not be quick enough to prevent compressor damage if compressor was continually started and operated with very suction pressures (it may only take a few minutes under the correct conditions).
This is why an LP switch must be fitted and why Copeland indicate the below warning in the manual for the compressor.



5.4 Charging procedure
CAUTION

Low suction pressure operation! Compressor Damage!


Do not operate



with a restricted suction. Do not operate with the low-pressure cut-out


bridged. Do not operate compressor without enough system charge to


maintain at least 0.5 bar suction pressure. Allowing pressure to drop below


0.5 bar for more than a few seconds may overheat scrolls and cause early

drive bearing damage.

The system should be liquid-charged through the liquid-receiver shut-off valve or through a valve
in the liquid line. The use of a filter drier in the charging line is highly recommended. Because
R410A and R407C are blends and scrolls have discharge check valves, systems should be
liquid-charged on both the high and low sides simultaneously to ensure a positive refrigerant
pressure is present in the compressor before it runs. The majority of the charge should be
placed in the high side of the system to prevent bearing washout during first-time start on the
assembly line.








Regards
VRVIII (& Copeland manual section from Grizzly):)

[desA]

For a 'typical' Copeland a/c scroll:
The 0.5 kg/cm2 (7 psig) lower limit is recommended for heat-pumps.
For general a/c operation, a lower limit of 2 kg/cm2 (25 psig) is recommended.
The LP cut-out should be set no lower than these values. If on start-up, the system trips, then respect the trip & correct the underlying causes.

The thing to understand is that at ~ 0.5 barg, Te,sat is ~ -16.92'C. If the delivery pressure is such that Tc,sat exceeds 45'C, then compressor discharge temp goes above 107'C. This is outside of the manufacturer's continuous operating envelope. The rise can be very rapid - especially if the evap superheat is also above 7-8K, due to low system charge.