Advise about Low Discharge Superheat alarm

[ishtiaq ahmad]

1 )We have 4Nos Mc Energy 143.2 HAST Air cooled screw chillers with Microtech 11 c plus controller. in 2nos chillers" Low Discharge super heat alarm" is often coming in one of the Refrigerant circuits due to which the compressor of the circuit shuts OFF .Kindly advise about the cause & Remedy of this alarm as the same is not available in the manuals.

2) An early reply will be highly appreciated.

[ishtiaq ahmad]

I am a new guy in A/C field. The above Chiller is in-operative due to above alarm. Would someone help me in troubleshooting by replying to my above mail?

[Rob White]

.

I don't know that specific system so I can only offer you general advice.

If the discharge superheat alarm activates it means the compressor discharge
temperature is below design perimeters or it could mean the probe is faulty.

Prove the probe is not faulty then look to see what could cause discharge temps
to drop. You need to measure both pressures and temps of the refrigerant as it
enters and leaves the compressor, then you need to compare it to one of the others
and see if anything is different.

Regards

Rob

.

[RusBuka]

Accident on discharge superheat temperature usually has one option - the compressor fills in with *****. Why fills in, these are already indirect questions. And the reasons are simple, from simply lack of an expense in the evaporator, to bypassing EEV or not adjusted controler.

[ishtiaq ahmad]

Does the probe mean Discharge Temperature Sensor?
The Discharge Temp/oil sensor of both circuits of defective chiller #3 shows Temp of 54 Deg c in chiller OFF condition.However the current of defective circuit #2( Bigger compressor 3200) of chiller #3 at 100% load is 138.7A While the current of O.K Circuit #1(smaller compressor 3100) of same chiller at 100% load is 145.2 A.The other operating parameters are as under.

Circuit #2(defective) at 100% load
Discharge Temperature = 69.7 Deg c
Discharge Super Heat 21.7 Deg c
Evaporator Temp -3 Deg c
Evaporator pressure 1.5 Bar
Condensing Temp 31.3 Deg c
Oil pressure 10.3 Bar
Water Temp Entering 11.8 Deg c
Water Temp Leaving 8.00 Deg c
Water pressure Entering 2.7 Bar
Water pressure Leaving 2.4 Bar

Circuit # 2(O.K chiller # 4) at 100% load
Discharge Temperature = 82.9 Deg c
Discharge Super Heat 32.8 Deg c
Evaporator Temp 2.5 Deg c
Evaporator pressure 2.2 Bar
Condensing Temp 50.2 Deg c
Oil pressure 12.3 Bar
Water Temp Entering 10.5 Deg c
Water Temp Leaving 8.5 Deg c
Water pressure Entering 2.7 Bar
Water pressure Leaving 2.3 Bar

The Low Discharge super heat Alarm in Defective circuit #2 of chiller # 3 occurs at 25% load when only 1nos Condensor Fan is running through Fantroll Control
kindly advise & help this new guy in trouble shooting the above Fault in the light of above information

[RusBuka]

In a defective contour judging by parameters a consumption of water subjectively below other contour. Temperature of evaporation of ***** is lower. You look a consumption of water, and the Target Superheat control in the controler.

As measure an superheat and overcooling on each contour at a full load. And an superheat on the economizer.

[ishtiaq ahmad]

I Would request Mr Rob White & other learned Members to reply to my mail dated 9th March13 10.57AM.Refrigerant is R -134a & NOT *****.Further Economizer is not available in the chiller