AIR COOLED CHILLER.

Eire79 said:

A.C.C 225KW, 371A F.L.A. on data plate.
PROTECTION;
SCHNIEDER NSX 400A MCCB WITH MICROLOGIC 3.2 TRIPPING UNIT SET @ Io 400A,Ir x1, Isd x4 AS INSTALLED BY CONTRACTORS 6YRS AGO AND CABLE IS 4X 150sq.
Unit has 4 compressor circuits D.O.L via 160 A SIEMENS Gg fuses.
The issue has been 2 no trips on the MCCB during the last week and looking for advise as to the possible cause be it a electrical issue or some mechanical fault in the compressor putting a strain on a compressor circuit starting. I have checked mains cable, all compressors and can not find any issue with them.
I also have put ammeter on incomer which has recorded 260 A per phase with all circuits running but i understand the ampage will be higher on startup,one thing to note is the the unit does not bring in all circuits at once it ramps up over time.
with regard the MCCB i have inspected the terminals and see no heat issue and have recorded a terminal temp of 32 degrees c across all.
Can MCCBs become faulty or the tripping unit or can anyone point to any other issues . Thanks.

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Pete999 said:

Are the condenser /evap coils blocked ? how often do yo clean these coils? are the filters clean ? could be a fouled Refrigeration cycle

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Eire79 said:

The chiller get serviced on regular intervals, but as you say if any of these are blocked etc will it be intermittant or a constant blockage.
whats the effects ?

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Eire79 said:

A.C.C 225KW, 371A F.L.A. on data plate.
PROTECTION;
SCHNIEDER NSX 400A MCCB WITH MICROLOGIC 3.2 TRIPPING UNIT SET @ Io 400A,Ir x1, Isd x4 AS INSTALLED BY CONTRACTORS 6YRS AGO AND CABLE IS 4X 150sq.
Unit has 4 compressor circuits D.O.L via 160 A SIEMENS Gg fuses.
The issue has been 2 no trips on the MCCB during the last week and looking for advise as to the possible cause be it a electrical issue or some mechanical fault in the compressor putting a strain on a compressor circuit starting. I have checked mains cable, all compressors and can not find any issue with them.
I also have put ammeter on incomer which has recorded 260 A per phase with all circuits running but i understand the ampage will be higher on startup,one thing to note is the the unit does not bring in all circuits at once it ramps up over time.
with regard the MCCB i have inspected the terminals and see no heat issue and have recorded a terminal temp of 32 degrees c across all.
Can MCCBs become faulty or the tripping unit or can anyone point to any other issues . Thanks.

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timbobelfast said:

Can you get me the motor sizes in kw etc, and I can put this design through software for selectivity.

Do you know the duty sequence as well?

I have seen plenty of MCCBs go faulty, Schneider and Eaton.

Any schematics for the set up as well?

Is the skid controlled by PLC? Has anyone tinkered with the logic?

You could try adjusting the lsd to max setting of 8 or 9 in the mean time

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timbobelfast said:

Can you get me the motor sizes in kw etc, and I can put this design through software for selectivity.

Do you know the duty sequence as well?

I have seen plenty of MCCBs go faulty, Schneider and Eaton.

Any schematics for the set up as well?

Is the skid controlled by PLC? Has anyone tinkered with the logic?

You could try adjusting the lsd to max setting of 8 or 9 in the mean time

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timbobelfast said:

OK, thanks for that.

I'll input the loads and see what it looks like.

Has there been any maintenance, eg greasing, filter changes etc?

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Eire79 said:

Just general maintenance carried out by external air con contractor, not sure what they check but will have a look at the dockets.

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timbobelfast said:

Any recent trips with the increase in ambient air temperature?

See attached which is similar to the way the Schneider ACB 'As Found' settings.

If maintenance has been tip top, and there have been recent trips then I would be sticking a power analyser at the upstream device and trend where the spike is occurring.

You could also trying adjusting the lsd setting at the MCCB.

But depending on the type of site or client that it is, will probably require an MOC!






View attachment 87779

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rapparee said:

So in my ignorance, I had to Google MOC

Apparently it means masculine of centre

Something about butch lesbians ?

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