Tip DS
I'm here.
- Location
- The Great Meme State
- Occupation
- Electrical Engineer
When reverse-feeding a step-down transformer, is it permissible from the perspective of Article 450.3 to treat the secondary as the primary? In other words, can I use the 250% rule for sizing the over-current protection device (OCPD) on the secondary, since it will be ACTING as the primary?
My concern (amongst others I'm not discussing in this thread) is the amplified inrush current that will be fed by the secondary, instead of the primary. I'm pretty sure nuisance trips will be an issue, if I'm limited to 125% OCPD for the secondary, which will be acting as the primary.
Before we derail the topic with all the various other issues surrounding the back feeding of a transformer, please understand this is not for production use. It is only for occasional use in testing, so I would prefer to focus on the Article 450.3 implications.
My concern (amongst others I'm not discussing in this thread) is the amplified inrush current that will be fed by the secondary, instead of the primary. I'm pretty sure nuisance trips will be an issue, if I'm limited to 125% OCPD for the secondary, which will be acting as the primary.
Before we derail the topic with all the various other issues surrounding the back feeding of a transformer, please understand this is not for production use. It is only for occasional use in testing, so I would prefer to focus on the Article 450.3 implications.
