Basic versions of VDA switchgear consist of two, three and four conducting feeders with vacuum load break switches, and one transformer feeder with vacuum circuit breaker for power transformer protection, or two conducting and two transformer feeders. All live parts are placed into gas-insulated steel container. The container is filled with SF6 gas, which provides mutual insulation of current path elements, as well as insulation to the earth level potential. The arc quenching takes place in vacuum interrupters built both in circuit breaker and load break switches. SF6 gas is not used as arc-quenching medium, so the gas replacement has been eliminated. This feature provides complete environmental acceptability of this product.
The traditional combination of load break switch and HRC fuses has been substituted with innovative sollution: three-positional vacuum load break switches and vacuum circuit breaker controlled by microprocessor-based overcurrent relay for power transformer protection. Besides the obligatory manual drive, ring main unit series VDA can be equipped with motor drive and set of releases for remote control of each device. There is possibility of complete automatization of distributive transformer substations, regarding various specific requirements for remote control and monitoring.
BASIC TECHNICAL SPECIFICATIONS
|Nominal data|| ||Three-positional vacuum load break switch||Vacuum circuit breaker|
|Rated power frequency withstand voltage 50Hz/1min.||kV||28||38||50||28||38||50|
|Rated lightning impulse voltage||kV||75||95||125||75||95||125|
|Rated breaking capacity||kA||0,63||0,63||0,63||20||16||16|
|Rated making capacity||kA||50||40||40||50||40||40|
|Rated short time withstand current 1 sec.||kA||20||16||16||20||16||16|
|Switch-off time (short circuit)||ms||-||-||-||45||45||45|