Maximum Overload Trip

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Knightryder12

Knightryder12

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Location
Clearwater, FL - USA
Occupation
Sr. Electrical Designer/Project Manager
Doing a project where we are changing out the old switchgear. The EC on the project called us out to discuss a potential issue with an existing chiller breaker wire size issue. Here is the issue:
Nameplate info on unit(see pic):
460v, 3 ph
MCA - 631
MOCP- 1000 (FUSE OR BRKR)
MAXIMUM OVERLOAD TRIP-533

This unit is currently running and has been running on a 600 amp breaker with (2)sets of #300 MCM cu for the last 25 years or more. The question I have is what does the term "MAXIMUM OVERLOAD TRIP" mean? I have never seen this term before. Also, what size OP and wire size would guys think this unit requires?
 

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This is telling you the maximum setting for overload you could use before the equipment is damaged by an overload condition.
 
infinity said:
Are you required to put it back as a code compliant installation? Looking at the nameplate it will probably run another 25 years just putting it back the way it is.
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That's what we were thinking too. But we have a scheduled shut down the 10th of July and the last thing I want is to have new breaker not be able to hold to start the existing chiller. This is a manufacturing facility and that would not be good.
 
I wonder if that maximum overload we are seeing is the setting for the overload relay on the starter and not the breaker.

The numbers indicate a type 3 starter package but I'm not sharp enough to know what all that means. If it is a factory packaged across the line starter I'd want something more robust than if it was a factory packaged VFD. My CVHE chillers are 750 tons and at worst had a solid state starter IIRC. The smaller units did have wye/delta.
 
Russs57 said:
I wonder if that maximum overload we are seeing is the setting for the overload relay on the starter and not the breaker.

The numbers indicate a type 3 starter package but I'm not sharp enough to know what all that means. If it is a factory packaged across the line starter I'd want something more robust than if it was a factory packaged VFD. My CVHE chillers are 750 tons and at worst had a solid state starter IIRC. The smaller units did have wye/delta.
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The Trane rep is telling us that it has a star/delta starter and that the RLA is 606A. Not sure how this has been working for the last 25+ years. Either way it's not a code compliant install, so I thing we need to change breaker and wire.
 
Knightryder12 said:
The Trane rep is telling us that it has a star/delta starter and that the RLA is 606A. Not sure how this has been working for the last 25+ years. Either way it's not a code compliant install, so I thing we need to change breaker and wire.
Click to expand...
Once you get past starting surge it probably never has run at full rated capacity, or at least never for long enough to trip on overload.
 
Knightryder12 said:
The Trane rep is telling us that it has a star/delta starter and that the RLA is 606A. Not sure how this has been working for the last 25+ years. Either way it's not a code compliant install, so I thing we need to change breaker and wire.
Click to expand...
According to your nameplate photo that number isn't even close. The unit should be run and the amperage read with a meter. That will show how the unit has run for 25+ year.
 
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