The Surge Performance of Cable-Connected Pad-Mounted Distribution Transformers

The lightning protection of pad-mounted distribution transformers supplied through buried cable from open-wire circuits was investigated in the laboratory. Several distribution transformers and field lengths of equivalent cable were connected to form a typical underground distribution layout of limited size. Cost and space limitations in providing valve-type arresters at each transformer place emphasis on obtaining over-all protection from only the cable-open wire-junction arresters. The influence of wave shape, cable length and characteristics, and the relation of the transformer basic impulse insulation level (BIL) were considered.