Ring main units series VDAΣ are built for nominal insulation level 24 kV, for implementation at operational voltages 12 (17,5) and 24 kV. Their purpose is distribution of electrical energy in transformer substation up to 2500 MVA; 10(20)/0,4 kV.
The ring main units series VDAΣ and are intended for indoor installation under normal operation conditions, in accordance with IEC 62271-200 and IEC 62271-1.
Distribution compact ring main units series VDAΣ have high reliability and availability. They are completely independent on environment conditions and their overall dimensions have been minimized in comparison to classic air-insulated switchgear equipped with load break switches.
Basic versions of compact ring main units series VDAΣ have the following combinations: Two ring main and one transformer feeder, three ring main and one transformer feeder, four ring main and one ring main feeder, two ring main and two transformer feeders and finally three ring main and two transformer feeders. Technical data regarding extensible modules are available on request.
Each module has gas-tight container filled with SF gas (degree of protection IP 65) in which are placed all apparatus and current path elements. The SF gas is insulation medium between live parts and to earth.
The current breaking in circuit breaker (transformer feeder) and load break switches (ring main feeders) takes place in vacuum interrupters.