Guidance and references are provided by this recommended practice for the design, manufacture, testing and selection of oil-immersed on-load capacity switching distribution transformers with rated frequency of 50 Hz/60 Hz, voltages of 10 kV or below, and rated capacity of 750 kVA and below. On-load capacity switching distribution transformers are transformers with two rated capacities and equipped with additional components to control the operating capacity for energy saving purposes.

This recommended practice provides guidance and references for the design, manufacture, testing and selection of oil-immersed on-load capacity switching distribution transformers with rated frequency of 50 Hz/60 Hz, voltages of 10 kV or below, and rated capacity of 750 kVA and below. On-load capacity switching distribution transformers are transformers with two rated capacities and equipped with additional components to control the operating capacity for energy saving purposes.

This document provides technical and test requirements and terminologies for on-load capacity switching distribution transformers. This includes the technical parameters of the transformers corresponding to the rated capacity, functional and performance requirements of the on-load capacity switching tap-changer and controllers, test classification, items and methods.