Compressor Damaged

[GHAZ]

Hello friends i was asked to look at a LT pack running on r408a , it has 4 bitzer 4G-20 SD compressors on it.2 of the orignal compressors broke down with mechanical failure and windings burned.They were replaced with remanufactured compressors and they also have failed. the suction pressure is 6psi, discharge 195 psi , oil pressure 25 psi, head temperature 93c , oil temperature 60c, oil pump 59c.Compared with other LT PACK the running conditions are the same. Has anybody come across this sort of problem, any suggestions very much appreciated thankyou

[taz24]

any suggestions very much appreciated thankyou

How old is the pack? The 408a is is a retrofill for 502.
What state is the oil in?
How long did the two rebuilds last?
Both comps failed mechanicaly and electricaly?

More questions than answers .

Cheers taz.

[Peter_1]

I think, there's more happening then you might expect.
Braking mechanically and electrical and then even 2 compressors???
Liquid slugging, something is definitely mis-wired electrically, was a burn out filter installed, was an oil sample taken from the sump, was the oil replaced in the other compressors, is the oil level OK, is the oil protection connected adn working,

A lot of questions but there's seriously something wrong.

[old gas bottle]

as peters says,oil and liquid is the starting point,if the systems old has it problems elswhere transmiting back to the pack.ie icing up ,cabinets or coils disconected, or is it just a dirty system !have the contactors been replaced at the time of the compressors ?has there been any short cycling going off,could be allsorts.

[Mark]

GHAZ

If the cause of failure cannot be determined in the field, you could ask for a failure report from the rebuild company to point you in the right direction, the report should state the oil condition etc.New switchgear on compressor failures is a impotant factor to consider.

With Kind regards
Mark