8BK 20 Under license of Siemens download 

Medium Voltage Switchgear, Air Insulated, up to 24 KV Metal-Enclosed, Metal-Clad, Single/Duplicate Busbar


       Rated short-circuit breaking currents from 31.5 kA to 50 kA
       Rated busbar normal currents up to 4000 A
       Rated feeder normal currents up to 4000 A
       Rated voltages from 7.2 kV to 24 kV

Typical uses

       Power stations, transformer stations and switching substations of public utilities
       Cement industry
       Automotive industry
       Iron and steelworks
       Rolling mills
       Food and fiber industry
       Chemical industry
       Mineral oil industry
       Offshore installations
       Railway power supplies
       Diesel power stations
       Emergency power supplies

Personnel safety

Protection against electric shock and ingress of solid foreign bodies
8BK20 switchgear provides both external and internal protection.

  • External protection is provided by
    • Complete enclosure of the panels in all operating states
  • Internal protection is provided by
    • Internal metal compartmentalization with enforced operation shutters, optional arc-resistant version of the busbar compartment
    • The inter-cubicle partitions; optional arc-resistant version
  • Degree of protection Standard version IP4X/IP3XD.Higher degrees of protection, such as IP31D, IP50 and IP51, can be obtained by additional measures.

Technical Data

Rated voltage kV 7,2 12 15 17,5 24
Rated frequency HZ 50 50 50 50 50
Rated short-duration power-frequency voltage KV 20 28 35 38 50
Rated lightning impulse withstand voltage KV 60 75 95 95 125
Rated short-circuit breaking current KA 50 50 50 25 25
Rated short-time withstand current 1s KA 50 50 50 25 25
                                                               3s  KA 40 40 40 25 25
Rated short-circuit making current KA 125 125 125 63 63
Rated normal current of busbar A 4000 4000 4000 2500 2500
Rated normal current of feeders A 4000 4000 4000 2000 2000
Width mm 800 800 800 1000 1000
Depth (min.) Single busbar mm 1650 1650 1650 2025 2025
Double busbar (back to back) mm 3560 3560 3560 4310 4310
Height (min.) mm 2050 2050 2050 2250 2250




  • Bolted steel profiles and sheets
  • Rails for accommodating the withdrawable part
  • Base cover optionally available
  • Surface treatment
    • Steel profiles and sheets galvanized
    • Doors and front frame powder-coated
    • Switchgear side walls powder-coated

Partitions isolate neighboring panels from one another

  • Galvanized sheet steel
  • With cutout for continuous busbars
  • Bushing plate with cast resin bushings for transverse isolation of busbars optionally available
  • Degree of protection with respect to neighboring panels: IP4X/IP3XD
  • Optionally in an arc resistant design

Pressure relief
When the pressure relief flaps are opened, the excess pressure in the panel in the event of an arc occurring is dissipated.

  • Galvanized sheet steel
  • Locked to prevent unintentional opening from the outside
  • Separate pressure relief flaps for busbar, withdrawable part and connection compartments


  • Bolted galvanized steel sheets subdivide the panel into
    • Busbar compartment
    • Withdrawable part compartment
    • Connection compartment
  • Degree of protection between the individual compartments: IP4X/IP3XD
  • Thanks to integrated cup type bushings, complete Compartmentalization even when the withdrawable part is in the connected position
  • Upper and lower mating contacts fixed in cup-type bushings
  • Enforced operated metal shutters for opening or closing the cup-type bushings when moving the withdrawable part
  • Metal shutters can be locked when the withdrawable part is racked out
  • Upper barrier (access to the busbar) or lower barrier (access to the cable) can be unscrewed independently of one another
  • Optional resistance to internal arcing of the busbar compartment

High-voltage door

  • Inspection window
    • Pressure-proof
    • For checking the withdrawable part position
    • For reading off the CLOSED/OPEN position indicator of the switching device, of the operating cycle counter and of the “closing spring charged” indication Lock
    • For locking or unlocking the high-voltage door (taking the interlocking conditions into account) with an interlocking key
  • Hand crank opening
    • Hand crank for charging the operating mechanism springs of the switching device
    • Opening closes automatically
  • Door handle
    • After the lock has been unlocked, the door is opened by lifting or is closed by lowering (taking the interlocking conditions into account)
  • CLOSED/OPEN pushbutton of the switching device
    • CLOSED/OPEN switching when the withdrawable part is in the connected position: When the door is closed, mechanically with pushbutton and tiltable extension mechanism for pushbutton actuation
    • CLOSED/OPEN switching when the withdrawable part is in the disconnected position: When the door is closed mechanically by means of pushbuttons (direct actuation)
  • Lever for tilting over the extension mechanism (see adjacent figure for operating principle)
  • Openings for withdrawable part actuation
    • For the hand crank for moving the withdrawable part (taking the interlocking conditions into account)
    • For the interlocking key of the withdrawable part (same key as for the high-voltage door).

Busbar mounting

  • On commercially available cast-resin insulators
  • Busbars bolted, length according to panel width


  • Metal compartmentalization to the withdrawable part and connection compartments with degree of protection IP4X/IP3XD
  • Busbar compartment continuous throughout the entire installation, transverse compartmentalization with respect to neighboring panels possible

Panel connection

  • Connection of cables or bars to current transformers or post insulators
  • Connection variants or types of installation are as shown in the illustrations
  • Earthing and short circuiting via earthing switch directly at the point of connection
  • Fixed-mounted voltage transformers within the current transformer protection zone

Low-voltage compartment

  • For accommodating the devices for protection, control, measuring and metering, e.g. bay controller SIPROTEC
  • Shock-proof partitioning from the high-voltage section
  • Pressure-resistant partitioning from the high voltage section
  • Control cables of the panel are flexible and have metallic covers


Contact Us

Central Office (Tehran):

Kavir BIdg. No. 24 Kaman Alley. Africa Blv Teharan , Iran.


Sales Dept.: +98 21 88787160 - 88783000

Projects Dept.: +98 21 88782941 - 88785661

General: +98 21 88677210 (10Line)


General Fax: +98 21 88789448




Factory (Yazd):

Electrokavir Co., Khezrabad Industrial Area, Yazd, Iran.


+98 351 7272591 – 7272954/6


+98 351 7272386