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Line impedance query

me1899
Hi 


I am looking at a job where a supply to a replacement CT scanner has to be calculated.


The current scanner is fed by a cable with line impedance 0.06 at source end of the sub panel that feeds it.


The new scanner must have a line impedance no more than 0.06 so basically I can't use the way on the current panel.


The client engineer has said to run from the intake and provide a cable calc to prove the line impedance is OK for the new scanner feed (this is D and B).


I am using AMTECH and was wondering if there was a way to output line impedance or if I need to show a calculation another way?


The client engaged a firm to do line impedance tests, and their report shows values measured between L1-L2, L2-L3 and L1-L3, but looks like they did testing at the sub panel and not at the intake.


This is basically like PSCC right? So I can get PSCC from AMTECH, divide by root 3 and work out impedance from there?


Am I on the right track? Assistance would be much appreciated.


Regards


Anisur
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  • Former Community Member
    0 Former Community Member
    Couple of points:


    1 - do you need generator back up to the scanner - they are an aggressive load and you need to be careful the generator can actually close onto the load step. Some are supported (as front line diagnostic tools) some are unsupported as they aren't used in emergency response


    2 - In terms of the system controls, they won't survive the blackout between LoM and Generator start - up to 15 seconds is permitted. So, you may need a small UPS to keep the "brains" functioning before the generator supplies bulk power. This UPS is usually part of the equipment supplier package


    Regards


    OMS
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  • Former Community Member
    0 Former Community Member
    Couple of points:


    1 - do you need generator back up to the scanner - they are an aggressive load and you need to be careful the generator can actually close onto the load step. Some are supported (as front line diagnostic tools) some are unsupported as they aren't used in emergency response


    2 - In terms of the system controls, they won't survive the blackout between LoM and Generator start - up to 15 seconds is permitted. So, you may need a small UPS to keep the "brains" functioning before the generator supplies bulk power. This UPS is usually part of the equipment supplier package


    Regards


    OMS
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