How to Read Graph for Circuit Breaker Testing

I agree with post#3.

I also recommend spending time with a qualified company engineer or contractor to gain experience in the field.

There are many variables to be considered;too many to list here.

No substitute for experience once you have a firm grasp of the basics.

You must do the "grunt work" first.

Everyone starts with no experience at the bottom of the totem pole.

Those that maintain their interest and curiosity ultimately end up at the top.

You have far to go, But you are on the right track.

The figures look too high as a very quick estimate The best solution for you to understand us to draw the curves on the graph for your settings, using what is already there as a template. So you have set the plug at 0.5. Draw a very fine line between the minimum and maximum settings where the curve goes from the vertical line to the angled line. Now draw a vertical line down at 0.5, stop when it crosses the line you just drew. Now draw a parallel angled line starting where your two lines cross. For now just take it down to the bottom of the page You now have a basic thermal curve. To read it correctly you work out the ratio of injected current over rating. So 1250/(1600x0.5) = 1.6 estimate that across the bottom, draw a vertical line from there and where it crosses your curve should be the trip time. A couple of points though. 1) you have not included the tolerance band, so it's not going to be exact, the catalogue should tell you what it would be 2) they generally either work or don't work. If you are getting strange times. Until you are confident, assume it's your error, not the OCR 3) as said above. It's vital that you understand how to setup and read the curves. Spend lots of time practicing before you even consider doing this on a real job.