Home / Specifications / Loop Feed and Radial Feed Pad Mounted Transformers
Loop Feed and Radial Feed Pad Mounted Transformers
Radial feed brings power in and stops there. Loop feed brings a cable in and back out, so the transformer sits on a loop and a fault upstream can be fed from the other direction. Loop feed needs six primary bushings instead of three, which is why it costs more and why utilities usually insist on it.
Radial feed
Three primary bushings. Power comes in and terminates. If the feeder upstream fails, the transformer is dark until the feeder is repaired. Simple, cheaper, and fine where an outage is tolerable.
Loop feed
Six primary bushings. Cable comes in and continues back out, so the unit sits on a loop that can be fed from either direction. A fault on one side is isolated and service continues from the other. This is standard on utility distribution and on most commercial campuses.
The practical difference when buying
Loop feed costs more because of the extra bushings and switching. More importantly it is usually not a field change, so ordering radial when the utility wanted loop means a new unit and a new lead time. Confirm this before the order, not after.
See also dead front and live front.
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