1. Introduction KYN28-12 indoor metalclad withdrawable switchgear is designed to be complete distribution equipment with three-phase A.C. singe busbar and single busbar section system having a rated voltage of 3.6~12kV and rated frequency of 50Hz.The switchgear is mainly employed in receiving and distribution of power energy from the network as well as starting of large-sized HV motors. In addition, the switchgear is provided with controlling, protection and monitoring functions. The switchgear conforms to IEC 298, GB 3906, DL/T404-91 and other standards. The switchgear itself owns five prevention functions such as prevention of misoperation of circuit breakers, prevention of pushing or pulling truck with load, prevention of closing earth switch under voltage, prevention of supplying power when earth switch is at the earth position and prevention of entering the electrical separation zone by accident. The switchgear selects not only VS1 vacuum circuit breakers but also ABB made VD4 vacuum circuit breaders, thus recogninzed as power distribution equipment with excellent performance. 2. Working condition 2.1 altitude: 1000m 2.2 temperature: -10celsius degree ~+40celsius degree 2.3 relative humidity: daily average value 95%, monthly average value 90% 2.4 saturated vapor pressure: daily average value 2.2 10-3MPa, monthly average value 1.8 10-3MPa 2.5 earthquake intensity: less than 8 degree 2.6 protect the product from fire, explosion, earthquake and corrosion atmosphere. 3. Main features: 3.1. the enclosure is completely adopts the aluminum-zinc alloy coated steel sheet, which are machined and bent by machine tool and then bolted; 3.2. all the operations are under the door closing condition 3.3. with high protection category, can prevent intruding of sundries and insects 3.4. simple efficient 5 protection function can prevent operating incorrectly 3.5. the removing compartment of the switchgear may be assembled with VS1(ZN63A) or VD4 vacuum circuit breaker according to customer s demand 3.6. the replacing of VCB is simple and the interchangeability of truck is good. 3.7. the cabinet body can be installed against the wall, so the maintenance can be made in front of the cabinet and the cover area can be reduced too. 3.8. cable compartment has enough room, can connect muti-cable 3.9. high speed earthing switch is used for grounding and loop short circuit 3.10. VCB vault, relay vault and cable vault can add extra heater separately according the demand of customer, in order to avoiding condensation pheromone and corrosion. 3.11. VCB vault and cable compartment can add extra lighting device separately, in order to convenient maintenance. 4. Main technical parameters 4.1 main technical of vacuum switchgear item unit parameter Rated voltage kV 3.6 7.2 12 Rated current A 630 1250 1600 2000 2500 3150 Rated frequency Hz 50 Rated short-time withstand current kA 16 20 25 31.5 40 Rated peak withstand current kA 40 50 63 80 100 Rated power-frequency withstand voltage kV 42/1min Rated lightning impulse withstand voltage kV 75 Rated duration of short circuit S 4 Degree of protection IP4X 4.2main technical parameters of vacuum circuit breaker Item Unit Parameter Rated voltage kV 12 Rated current A 630 1250 1600 2000 2500 3150 Rated short circuit breaking current kA 25 31.5 40 Rated short-time withstand current kA 25 31.5 40 Rated short circuit making current kA 63 80 100 Rated short-time power-frequency withstand voltage kV 42/1min Rated lightning impulse withstand voltage (peak) kV 75 Rated short circuit duration S 4 Closing time (rated voltage) ms 35 t 70 Opening time (rated voltage) ms 20 t 50 Rated breaking times of short circuit times 50 (40kAis 30) Mechanical life times 20000 4.3main technical parameters of operation mechanism Item Unit parameter Rated operation voltage Opening coil V DC220/110 AC220/110 Closing coil Rated operation current Opening coil A (DC/AC)220/110V: 0.9/1.8 Closing coil (DC/AC)220/110V: 1.0/2.0 Power of energy storage motor W 70 Rated voltage of energy storage motor V DC220/110 AC220/110 Energy storage time S 15 5. Structure instruction The basic structure of switchgear panel comprises the panel itself and a removing part (truck). The enclosure and clap-board of the switchgear is bolted with Al-Zn alloy coated steel.Enclosure protection degree of switchgear is IP4X, and the protection degree of every vault is IP2X. 800/1000*1500*2300mm.