What do these dials do on an HKD 65k molded case circuit breaker trip unit? 1

[bdn2004]

Attached is technical data sheet for a Cutler Hammer HKD3400F 300 Amp circuit breaker.
Per our coordination study we are going to set the breaker at an Instantaneous pickup of 5.

In looking at this sheet and the actual breaker and I'm assuming that means set the one on the far left to 5.

What do the other adjustments do? They aren't in our software to manipulate the TCC curve.

 

[bdn2004]

Here's a picture of the actual breaker....

 

[PowerWagon81]

It is the Inst. pick up for each phase. Crazy I know but you can set each phase to a different Inst. level.

 

[jraef]

That's right, each phase is separately adjustable. Not too common any more, but it used to be.

A setting of 5 (500% of the rated amps) is pretty low for the instantaneous (short circuit) trip, are you sure about that?


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[Sn00ze]

@jraef, i am reading 10.

 

[bdn2004]

Wow...You would think the literature would be this easily discernible. Hey Cutler Hammer is it too much to ask to put an A, B, C above each dial?

This is a feeder breaker to a panelboard. Either way - setting 5 or setting 10 it coordinates with the main circuit breaker, and provides the lowest value possible for arc flash.

What is the advantage of the higher setting? Is it just nuisance trips we are worried about?

 

[RRaghunath]

"What is the advantage of the higher setting? Is it just nuisance trips we are worried about?
Great" - depends on what is downstream.
If it is motor that takes more than 5 times the MCCB rating as its starting current, you may have a nuisance trip.