General requirements for Siemens 8DJH switchgear
1.Three-poleprimary enclosure, metal-enclosed
2.Weldedswitchgear vessel without seals, made of stain- less steel, with welded-in bushings for electrical connec- tions and mechanical components3.Insulatinggas SF6 (fluorinated greenhouse gas)4.Maintenance-free componentsunder normal ambient conditions according to IEC 62271-1 and VDE 0671-15.Three-position switch-disconnector withload-break function and make-proof earthing function6.Vacuumcircuit-breaker7.Cable connection with outside-coneplug-in system
– In ring-main and circuit-breaker feeders with bolted contact (M16)
– In transformer feeders with plug-in contact or optionally with bolted contact (M16)
- Wall-standing or free-standing arrangement
- Pressurerelief downwards, optionally to the rear or upwards via pressure absorber systems.
Interlocks
- According toIEC 62271-200 and VDE 0671-200
- Logicalmechanical interlocks prevent maloperation
- Logicalmechanical interlocks and the constructive
features of the three-position switches prevent mal- operation as well as access to the cable connection of the feeders and HV HRC fuses under voltage
- Impermissibleand undesired operations can be prevent- ed by means of locking devices provided at the switching devices
- A detailed description of allinterlocking options is available on page 51.
Insulating system
- Switchgearvessel filled with SF6 gas
- Features ofSF6 gas:
– Non-toxic
– Odorless and colorless
– Non-inflammable
– Chemically neutral
– Heavier than air
– Electronegative (high-quality insulator)
– Global Warming Potential GWP = 22,800
- Pressure of SF6gas in the switchgear vessel (absolute values at 20 °C):
– Rated filling level: 150 kPa
– Design pressure: 180 kPa
– Design temperature of the SF6 gas: 80 °C
– Operating pressure of bursting disc: ≥ 300 kPa
– Bursting pressure: ≥ 550 kPa
– Gas leakage rate: < 0.1 % per year.
