The vacuum circuit-breakers of type VD4/S are intended for indoor installation in air-insulated switchgear systems. They have a switching capacity capable of handling the loads occurring at start-up and shutdown of equipment and plant units both in normal and in fault state. Vacuum circuit-breakers have particular advantages for use in networks where there is a high switching frequency in the working current range and/or where a certain number of short-circuit breaking operations are expected. Type VD4/S vacuum circuit-breakers are suitable for autoreclosing, and have exceptionally high operating reliability and long life. The vacuum circuit-breakers of type VD4/S, designed in column form, can be supplied both as individual units for SM6 , Uniswitch, HXGN, etc.
Standards and specifications
The switchgear complies with the following specifications in accordance with DIN,VDE and the relevant IEC publications:
• VDE0670, part1000 and IEC60694
• VDE0671, part100, and IEC62271-100.
Installation and operation
The relevant specifications are to be taken into account during installation and operation, particularly:
• DIN VDE0101, Power installations exceeding AC1 kV
• VDE0105, Operationof electrical installations
• DIN VDE0141, Earthing systems for special power installations with rated voltages above1kV
• Accident prevention regulations issued by the appropriate professional bodies or comparable organizations.
Normal operating conditions
Design to VDE 0670, part 1000, “Common specifications for high-voltage switchgear and controlgear standards“ and IEC-60694, with the following limit values:
• Ambient temperature:
–Maximum24 hour average +35℃
–Minimum (according to “minus5 indoor class”) –5℃
–the average value of the relative humidity , measured over a period of 24 h, does not exceed 95%
–the average value of the water vapour pressure, over a period of 24 h, does not exceed 2,2 kPa
–the average value of the relative humidity , over a period of one month, does not exceed90%
–the average value of the water vapour pressure, over a period of one month, does not exceed 1,8 kPa
• Maximum site altitude: ≤1000 M above sea level.
Special operating conditions are to be agreed on by the manufacturer and user. The manufacturer must be consulted in advance about each specialoperating condition:
• Site altitude over1000 m:
–Allow for the reduction in the dielectric strength of the air .
• Increased ambient temperature:
–Current carrying capacity is reduced.
–Provide additional ventilation for heatdissipation.
–A void the risk of corrosion or other damage in areas:
• with high humidity and/or
• with major rapid temperature fluctuations.
– Implement preventive measures (e.g. electric heaters) to preclude condensation phenomena