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Equipment Evaluation SCCR Rating
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Author:  jsoar [ Wed Apr 22, 2026 12:20 pm ]
Post subject:  Equipment Evaluation SCCR Rating
The SCCR rating on the control panel's nameplate is 10kA, which is why my equipment evaluation is failing. Bussman KLU 800A fuses are utilized in an 800A fused disconnect that supplies the control panel with two 500 kcmil at a distance of fifty feet. An ABB XT6-N 800A main breaker with an AIC rating of 35K is located inside the control panel.

I've been looking for a way to reduce the fault current to less than 10kA. Adding a 750 KVA transformer after the disconnect was the only fix I could find.

Is there something I'm missing?

Attachments:
File comment: Panel Diagram
Medium Pressure Control Panel Diagram.jpg
Medium Pressure Control Panel Diagram.jpg [ 110.51 KiB | Viewed 197 times ]
File comment: Equipment Evaluation
Medium Pressure Control Panel Oneline Equipment Evaluation.jpg
Medium Pressure Control Panel Oneline Equipment Evaluation.jpg [ 79.84 KiB | Viewed 197 times ]
File comment: Oneline with the option for a 750 KVA Transformer.
Medium Pressure Control Panel Oneline.jpg
Medium Pressure Control Panel Oneline.jpg [ 72.12 KiB | Viewed 197 times ]
File comment: Bill of Material
Medium Pressure Control Panel.jpg
Medium Pressure Control Panel.jpg [ 173.28 KiB | Viewed 197 times ]
Author:  bbaumer [ Wed Apr 22, 2026 2:19 pm ]
Post subject:  Re: Equipment Evaluation SCCR Rating
Did you model the drives to allow motor contribution through the drives? If they aren't regenerative drives and don't have bypasses or have bypasses that won't be used or can't be used without damaging the compressors or the process they are part of you could check or uncheck the boxes that allow motor contribution and see what that does. Probably will help some but not get you there. I looked up the noise filter and it says it is for applications using regenerative drives so you may be stuck if that is what you have. If you are allowing fault contribution through the drives, does the noise filter impedance have an effect on motor fault contribution? You'd have to model those to, to figure that out.

I don't see the sccr/withstand rating on the filter data sheet: https://coselusa.com/wp-content/uploads ... _TSD-S.pdf but I do see that rating on this page: https://www.cosel.com/en/product/noisefilter/TSD and here: https://www.cosel.com/en/lp/lineup/appl ... index.html

I spent enough time looking into it but it seems as though Cosel has had some of their filters tested in combination with some breakers and if they haven't the "assumed" value for that filter size is 10kA. Here is another link on this if you want to research further: https://www.cosel.com/en/coselplus/technical/111

Is this an existing installation or new design?

Reactors are another option.

Artificially increasing feeder length could be another option but I expect it would border on ridiculous.

Can you reduce the 2 sets of 750's to 600's or 500's or is voltage drop an issue? Your feeders are pretty long. Reducing those 750's to something smaller would help.

If this is a new project, could you locate B-2HA closer to the compressors and make it's feeder longer and the compressor feeders shorter? That may help or may make it worse. I don't know without modeling it.
Author:  jsoar [ Wed Apr 22, 2026 2:44 pm ]
Post subject:  Re: Equipment Evaluation SCCR Rating
B-2ha is existing. The medium compressor control panel and fused disconnect is new installation. The original feeders is (2) 500 kcmil at 50 feet. I was just changing the feeders to different types to see if it would make a difference. This is all I have for the compressor data.

Attachments:
File comment: Medium compressor
2-1_Atlas_Copco_Medium_Pressure_Compressor_Cabinet_Details.pdf [1.74 MiB]
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