Yea good week, will be checking the oil levels tomorrow and probably draining more.
Yes I will help if I can, I'm still getting used to how it all works - how do the rep points work?
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Yea good week, will be checking the oil levels tomorrow and probably draining more.
Yes I will help if I can, I'm still getting used to how it all works - how do the rep points work?
This has been a great thread and really enjoyed the updates Martin, been a hectic week for me so only just caught up on your scenarios.
Getting Glens saliva levels up to drooling levels again is fun to see! :D
Getting the grey cells working again. Been wracking my brains over this one as it was an overcomplicated control strategy hmmm. Anyway Martin the settings for the EKC 316A look OK , but from memory the control strategy is as follows. The Compressor pack controller runs the system suction pressure somewhere about minus 3 Deg C (3.5Bar) on R407A. This would give a room temperature of say minus 2 Deg C. The room temperature is controlled by the EKC 361 controllers driving the ICM evaporator pressure regulators to throttle the suction pressure at the evaporators to maintain approx. 4 Deg C . (EKC 361 Set point 4 deg C) via its S3 sensor.
The CC210 controllers are set approx 2 Deg C , with a small Differential.
The Defrost heaters in this case are not actually defrost heaters they are used to heat the room if the temperature drops below the 4 Deg C setpoint of the 361. The CC210 energises the heaters if the room temperature drops below 2 degrees C.
If the temperature drops below 4 Deg C the ICM valve should close to keep the temperature from falling further and damaging the product, if the temperature falls below 2 Deg C the CC210 should stop the EKC 316A and energise the defrost heaters with the evaporator fans running to bring the room temperature back up to the 4 DegC . As the temperature rises the EKC 361 detects the temperature increase and the ICM should start to open causing cooling to start again.
These controls had various inter locks holding bits ON or OFF. I never saw the finished electrical drawing or who set the system up so I am not surprised that it has problems .
The set up is not quite a conventional fridge plant as most of this was done via a consultants demands for belt and braces safety for the Bananas, so I would be interested as to how the plant is actually set up on each control.
Have you got the settings for the CC210, EKC 361 and the pack controllers cant remember if its the PC 530 or the later AK 730/840 type. But their settings will all have relevance to making a good plant or a bad one.
But as the other lads have said if the ICMs are being held closed and the coolers are filling with liquid as the ICM s open liquid will rush back to the compressors causing oil to be pum,ped around the system and then becoming trapped in the closed down evaps. These situations will vary with store loading etc.
The Defrost heaters being used to heat the rooms is due to the cold ambients around the docks area at certain times of the year Please send any further controller data so that I can advise further , Be careful what you change as it could affect something else in the system Glenn
Hi Ranger
The ICM valve with ICAD was selected as the plant is controlled remotely but yes they would have worked but would need manual adjustment for different fruits. This plant is on the dockside and is not easy to access due to heavy traffic and so everything is centrally controlled an d monitored Glenn
Hi Glenn, I'm sorry but either a lot was changed after you selected the equipment or the person who actually installed/commissioned everything decided to change how it all works. The system has been set up as follows;
- Room temp set at 4 degrees for citrus fruit (this is minimum temp possible)
- Room temp is controlled via the cc210 sending a signal to the relay controlling the two EKC's
- The ICM controller EKC361 is set at -1 and has been since I've been here and the old bloke who 'showed me the ropes' when I first started who was from the install company said this as correct as it maintains the desired superheat in the evap.
- The heaters are controlled via the cc210 and due to a minimum allowable diff of 3 degrees (R36) will not activate until the store has got to 0.9 degrees. This is very poor design as by the time the store has dropped to this temp and brought the heaters in, the Testo alarm system has gone mad and the fruit will have frozen. As I said 3 degrees is the minimum value with the cc210 but on the newer controllers which I've just had installed in another store, (cc550) this value starts a 1 degree, which is a lot more reasonable.
- I would absolutely love to say the plant controllers are any model of Danfoss but unfortunately they are not. They are Mercury Pack Controllers - which are not connected to the network, nor the danfoss front end and so are not visible from afar or even up close! I believe to access the settings and values read by the controller I would need a laptop and a program and some idea what I'm doing! ha
Anyway as mentioned yesterday and checked this morning - the 'on' input for the ICM valve has been moved to the common side of the relay and a minimum opening degree of 10% has been added to each evap. Now when in off cycle or defrost, the EEV closes as it should and the ICM is either 100% open or a minimum of 10% depending on the value of S3. This allows the comps to effectively pump all of the oil and gas back, prevents oil build up in the evap and prevents refrigerant slugging.
Martin
Get Glenn those danfoss settings asap, compressors tripping on oil could be down to liquid flood back, guys add a "bit" of oil to overcome and suddenly you've a 100litres more than you need! Are oil seperators working? Checked suction and liquid line filters?
Hi Martin
Just to clarify the controls a bit. You say the the EKC 361 is set to -1 Deg C . The EKC 361 +ICM valve has NO relation to the evaporator superheat whatsoever , as the ICM valve is in the suction line between the evaps and the compressors. The ICM valve simply throttles the suction pressure inside inside the evaporator, by controlling the evaps pressure you control its temperature. This part of the system was to be the main temperature control as the ICM modulates keeping a constant air of the coil temperature.
The EKC 316A plus ETS valves control the superheat of the individual evaporators and that is their prime objective.
By setting the EKC 361 to minus 1, basically the ICM will be 100% open as it will never see -1 as the CC210 kills it at +4.
I Knew when this was designed unless they had a good commissioning engineer it would be a disaster, sounds like you had Clint Eastwood or the Sundance Kid commission it. If you have the wiring diagrams for the control panel I would like to have a swift look at them Glenn
Hi Glenn,
I think I know where this has gone wrong but will triple check when I go back in and also send you some wiring diagram however I'm off for a week now. When I was playing around with the controllers and monitoring the values of both controls I noticed the S3 input which should be the air on to the coil appears to be reading the coil air off temp as if an S4 instead. This would make more sense of -1 set point. Either change in design or probe has been put in wrong place?
Hi Al - I mentioned in earlier post that I've recovered a lot of oil from the pack so far I estimate about 15L that was not needed and this was due to the ICM closing during off cycle. However if what Glenn is saying was implemented and the EKC361 was getting its temp input from the S3 then theoretically it would be open during off cycle as the temp would be above 4 degrees - BUT the way it has been wired means both the EKC controllers are getting there on signal from a digital input off of the CC210 and so when the CC210 is in off cycle the relay to both EKC's is powered down and when that happens they both close shut even if a minimum opening degree is set.
Hi Al - I mentioned in earlier post that I've recovered a lot of oil from the pack so far I estimate about 15L that was not needed and this was due to the ICM closing during off cycle. However if what Glenn is saying was implemented and the EKC361 was getting its temp input from the S3 and was set to 4 degrees then theoretically it would be open during off cycle as the temp would be above 4 degrees - BUT the way it has been wired means both the EKC controllers are getting there on signal from a digital input off of the CC210 and so when the CC210 is in off cycle the relay to both EKC's is powered down and when that happens they both close shut even if a minimum opening degree is set.
Glenn I can't stop thinking about what you said about the ICM having no relevance to the superheat control.... Surely the opening degree of the valve which is controlled via the air off probe is maintaining the superheat in the evap? The 316 uses the S2 pipe probe and transducer on the suction line between the evap and ICM to calculate the superheat so this means the two controllers are working together?? I'm really sorry if I have this wrong but if the ICM isn't controlling the superheat then what is?
It's my understanding that the 361 is set 5 degrees lower than room set point as this is the optimum air off temperature to achieve target superheat? Thus allowing all refrigerant to be boiled off before heading back to comp and flooding it. The 361 controlling the superheat like this allows the 316A to calculate the superheat and allow in as much refrigerant as required. They have to work together like this because they are only getting an on signal from the cc210 they are not directly controlling the room temp. Again sorry if my refrigeration theory is incorrect but I'm sure this is the way it's working. Can anyone else say if they think this sounds correct?
Martin
Not sure how many evaps are off the pack, but if the suction valve was closing on defrost, unless the coolers are all defrosting at same time then room temps must be all over the place?
From a super heat perspective, the suction transducer would be S2 with S1 being a probe strapped after the EEV, but am open to correction on that as it's a good while since i worked on danfoss aKV's.
Have there been many compressor failures?
There are 6 evaps off the pack but each has its own ICM and each are separately controllable so 1 can be in defrost at a time. The EEV is calculating the superheat from S2 pipe probe and transducer both located on the suction line between the evap and ICM
Hi Martin
The idea of the control was similar to the older plant on this site. If you ignore the CC210 controls and concentrate on the Pack controllers, the EKC316A 's and the EKC 361's and the ambient temperatures around the stores summer and winter.
The pack controllers control the systems minimum evaporator pressure/temperature say at -4 Deg C by switching compressors on or off to match the desired system capacity requirements to maintain the suction condition at -4.
The EKC316A controllers driving the ETS valves with information from the S2 Sensor and the suction pressure transducer control the liquid injection into the evaporators and control the Superheat in the evaps at around the design set point of between 4 and 7 Deg K superheat. These controls try to operate the evaporators with maximum efficiency and lowest stable superheat.
The EKC 361 with the ICM/ICAD motor simply modulates the suction(evaporator) condition inside the evaporator. The pack is running at -4 Deg C so the EKC 361 modulates the evaporator pressure/temperature so that the air OFF the coil cannot drop below 4 Deg C (EKS 361 setpoint). At this time the EKC 316A is still controlling the S/heat between 4-7 Deg K.
During the warm months with the ambient higher than 4 degrees , the cold store will absorb heat through the fabric of the store , and the product respiration load etc, so the pack still runs some compressors keeping the suction at -4 C , the EKC 361's are running holding the evaporator condition up at 4 Deg C .
During the cold winter months the cold store temperature will fall below the desired 4 Deg C .At this point the EKC 361 controls will force the ICM valves to close trying to raise the store temp up to the design 4 DegC. But the ambient outside the store is still very cold dragging the in store temperature below the 4 Deg. The pack now switches the compressors Off. At this point the CC210 thermostats come into play , as the in store temperature plummets below 1 Deg C the EKC 316A controller is switched OFF and the Defrost heaters are now energised with the Evap fans still running.
As the temperature rises above the CC210 differential setting the heaters switch OFF , the EKC 316A is restarted and the EKC 361 starts to open the ICM valves. The suction pressure starts to rise above the set point of the pack controller and the compressors now start to cycle in, and so on.
The EKC 361 when it starts to throttle to close the ICM, this changes the pressure and the temperature of the evaporator the temperature S2 and the pressure converted to temperature (S1) of the EKC 316A begin to equalise to 0 superheat or slightly negative -1 superheat. This causes the ETS valve to be driven closed (No more liquid injected.)
Sounds complicated but is easy when you understand the demands of the system. As I said only myself and one other understood how it was designed to work but like the design for a racehorse its lost in translation and you get a donkey . Send me your Mobile and Ill text you my contact details Glenn
If the 361 was set at 4 and was reading the air on, all of what you just said would make sense :) and I believe that's how it should be but as I said earlier whoever installed the probes has put them infront of the air off and so the 361 cannot be set to 4 as it would shut the ICM as soon as the evap started cooling as the evaporating temp is about 0. This must be why it is set to -1?? I really need you, the commissioning engineer and the electrician in a room together to sort all this out! My number is (phone number removed to stop the spammer, sent to Glenn via PM, Brian_UK)