Selective coordination charts (from ABB)

Status
Not open for further replies.
L

lielec11

Senior Member
Location
Charlotte, NC
Occupation
Electrical Engineer (PE)
I have a chart from ABB indicating that an upstream/downstream breaker combination is selectively coordinated up to 14kA. However, when I put these curves into SKM, they actually overlap in the INST/short-time region. In the image below, I'm talking about the blue/purple curves. The tables tell me they should be coordinated, however, the curves do not. We submitted our report indicating they don't coordinate based on the curves, however, the EOR has come back saying otherwise.

I remember watching a presentation by Thomas Domitrovitch (from Eaton) stating that the tables are actually to determine selectivity BEFORE 0.01s and that the TCC curves also need to be fully coordinated as well. Any input on which train of thought to lean on here?

1611682154751.png

Thanks
 
I believe Tom D mentioned using the tables that all of the breaker manufacturers have to determine the coordination below the 0.01 time.
Using just the curve, I see this breakers as coordinated above the 0.01 second time as long as the available fault current does not exceed 15kA.
 
dkidd said:
Maybe this will help:

Click to expand...
We currently do not pay for this feature in SKM so I cannot go through it on our project, but thanks for the reference.

don_resqcapt19 said:
I believe Tom D mentioned using the tables that all of the breaker manufacturers have to determine the coordination below the 0.01 time.
Using just the curve, I see this breakers as coordinated above the 0.01 second time as long as the available fault current does not exceed 15kA.
Click to expand...

Thanks, Don. I tend to agree just always like to get another opinion in certain situations.

Thanks, John for the link to the other thread, I'll go through that as well!
 
Status
Not open for further replies.
Top