formation of acid in the system

[ah fai]

hello, all

Daikin compressor motor winding burnt frequently
1. any sign for formation of acid in the system?
2. daikin 37kw water-cooled chiller compressor running with 52Amp, its correct?
refrigerant - R22
discharge pressure at condensor outlet - 260 psi
suction pressure at compressor - 60 psi

3. all the electrical component is working good...

pls somebody give me solution for this...
thanks.

[Grizzly]

Ok.
To determine acid try a acid test kit, available from most good refrigeration wholesalers.
Chiller suction pressure is at approx 1c how does that compare with you chiller setpoint.
Whereas the discharge pressure equates to about 49c, which for U.K. I would say was high!
But in Malaysia I guess you would be looking at more like a 45C condensing envelope?

So your local settings may not be to out of range? You may be able to advise?
If you could give more info on the chiller then I/ We may be able to advise on the amperage drawn.
Cleaning up after a motor burn out is quite involved and very specific or else further burn outs are very likely to re-occur.
Have you used a burn out filter? reclaimed and recharged? Was a vacuum pulled before recharge.
Voltage fluctuations can cause a burn out, as will air in the system and many other causes.

To be accurate more info is needed.
Suffice to say if this is a re-occurring problem, you need to do more on reinstatement!

Grizzly.

[FrankieBoy]

dont reclaim and recharge use virgin charge unless you can use a burnout filter to run old charge through better using virgin

[install monkey]

have the contactors been changed since the last burn out? is there a delay on compressor cycle time?
is there a start and run hour counter what are they reading? is there 3 phase protection to stop 2 phasing??
any hot joints on supply cales/switchgear? fit a suction burn out drier and moniter the pressure drop through this and remove after a while. is oil pressure ok?

[FrankieBoy]

i have would like know why frequent burnout

[install monkey]

you need to look at the history of the machine, faults,repairs made, service history and ensure that the maintenance is carried out by competant people, could be a loose compressor terminal,crankcase heater failed

[FrankieBoy]

frequent burnout how can that happen i would get sacked

[ah fai]

thanks for reply..

i done acid test with compressor oil and the result is PH5.7
it is possible the reason for motor coil burnt? how can the refrigeration system become acid?

can somebody explain me about
1. delta T
2. Ice bank evaporator design, principle and the temperature
3. relation between compressor and expansion device

thanks a lot

[Grizzly]

dont reclaim and recharge use virgin charge unless you can use a burnout filter to run old charge through better using virgin

Good point Frankie.
I should of been clearer with the possible actions.

Given the questions being asked ah fai.
I would get another refrigeration engineer involved.
You are describing a classic chicken and egg scenario.
The only way to now resolve your dilemma.
Is to now start again with everything clinically correct.
You have not said who has set to work this system having repaired it?
All here have the same concern.
The repeated failure?
Grizzly

[goshen]

HI
refrigeration 101
good luck

[buddy]

ah fai,

Grizzlys correct.

And having worked in Asia a lot I would bet my dogs life on it (well perhaps not my dogs life) that the system had an original burn out and the compressor replaced with no acid test or system clean up performed, many many ref technicians just have never even heard of an acid test kit or how to conduct a system clean up properly.

The root cause of the original failure might still be there to compound your problem also.

Question?
Have you tried smelling the gas/oil?

[D.D.KORANNE]

Winding burn outs probable reasons :
@ the discharge temp of refrigerant more than recommended temp
@ compressor operates without any high temp cut off ( for a long time)
@ frequent start stop of compressor ( more than 10 per hour)........ Check with comp manufacturer
@ metal/abrasive particles in circulation with refrigerant & striking winding
@ metal like / hard particle /chip logged up in winding & flexing of winding ( due to heat) damages winding insulation
@ moisture in system reduces dielectric strength of winding
@ voltage imbalance between phases more than 2%
@ frequency variation/modulation
@ winding temp monitoring device not functioniing
@ acid formation due to moisture & high temp

[w.l.ong]

hi ,
i agree with Buddy post,
not many people in asia check or look for the root of the cause in coil burn,
it not just rewing back the coil and install back without open the compressor parts for cleaning as acid already build up.

but for me i have to play Safe, i have to check every thing, open up all the comp. parts for cleaning, refill with new gas, check SH,SC, electrical control, oil change after acid test.
i can't let it fail as customer has paid for our service and trust.
in asia, the CT for air cooled is 50C, as our ambient is about 35C.

w.l.ong