Fault rating of DC rectifier / charger cabinet

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Charz

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We have 125VDC charger which charges 62 Cells lead acid battery bank
The incoming 3 phase 480V AC to the Rectifier provides a source of AC short circuit current.
The lead acid battery bank provides a source for DC short circuit current.

I understand that rectifier limits the short circuit to its rated current.

In this case, what should be the equipment fault level rating? Which short circuit current should the DC rectifier cabinet withstand?
 
I would normally use a semiconductor rating than a fault rating.
 
1) The 480V AC input Main breaker would be selected according to the available fault current
2) The DC breakers will be selected based on the short circuit current from the battery bank + Rectifier rated current ( as it is current limiting type)

How would the equipment fault level (overall), SCCR be decided?
 
Charz said:
1) The 480V AC input Main breaker would be selected according to the available fault current
2) The DC breakers will be selected based on the short circuit current from the battery bank + Rectifier rated current ( as it is current limiting type)

How would the equipment fault level (overall), SCCR be decided?
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We normally use HRC capacitors.
 
SCCR is for upstream sizing so the AC numbers go on the cabinet. The purpose of the SCCR rule is so electricians don’t have to figure out the engineering of the possibly obscure internal component design.

Since the rating is for the equipment and batteries can be changed it would not even make sense to apply a DC SCCR.
 
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