Abstract
Recently the demand for electrical energy has been increasing rapidly, hence the EHV underground cables as well as the EHV transmission lines are repuired.
As the insulation of these EHV cables, roil impregnated papers are generally in use. The electrical characteristics of this material is influenced very much by the degree of vacuum drying.
This paper describes the large vacuum drying systems for electric cables set recently in our company which has the newest vacuum pump systems. It consists of a vacuum tank and pumping system as follows :
(a) [vacuum drying tank] of internal diameter 5000mm, internal depth 3500mm and volume 60m3.
(b) pumping system consisting of a main pump and its fore pumps, i. e.Mechanical booster pump (3450 M3/hr) as a main pump and mechanical booster (1030 M3/hr) Oil Rotary pump (3000 l/min) and Nash pump (4700 l/min) as fore pumps.
