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 Post subject: Harmonic Correction Unit?
PostPosted: Wed Jul 20, 2016 3:00 pm 
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Would a Harmonic Correction Unit impact the incident energy during an arc flash in an MCC line-up? :?: :|


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 Post subject: Re: Harmonic Correction Unit?
PostPosted: Wed Jul 20, 2016 3:33 pm 
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jdelgado wrote:
Would a Harmonic Correction Unit impact the incident energy during an arc flash in an MCC line-up? :?: :|


It depends on what type it is. There are lots of ways to do "harmonic correction".

If it is some kind of filter, whether it consists of just series inductors, or just parallel capacitors, or a combination of both (LC filters), the result is that you are adding impedance to the system even though it is frequency-sensitive. This decreases the available fault current and hence the arcing current. Although this sounds like it will reduce incident energy if the overcurrent protective device is working on an inverse time curve then the net result is that it increases rather than decreases incident energy because it will take longer for the overcurrent protection to trip.

If it's a UPS or equivalently a "line conditioner" where it is essentially a cycloconverter and if there are no non-semiconductor paths through the device then the semiconductor acts as a very fast fuse or will be protected by very fast fusing and thus incident energy will be low due to current limitations of the semiconductors.


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 Post subject: Re: Harmonic Correction Unit?
PostPosted: Wed Jul 20, 2016 3:35 pm 
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Thanks! :)


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