8BK 20 Under license of Siemens |
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Medium Voltage -MV- Switchgear, Air Insulated, up to 24 KV
Metal-Enclosed, Metal-Clad, Single/Duplicate Busbar
Application
■ 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
■ Mines
■ Food and fiber industry
■ Chemical industry
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■ Mineral oil industry
■ Pipelines
■ Offshore installations
■ Electrochemical
■ Petrochemicals
■ Railway power supplies
■ Shipbuilding
■ Diesel power stations
■ Emergency power supplies
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Personnel safety
Protection against electric shock and ingress of solid foreign bodies
8BK20 switchgear provides both external and internal protection.
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External protection is provided by
- Complete enclosure of the panels in all operating states
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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
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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 |
Dimensions |
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|
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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 |
Design
Frame
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Bolted steel profiles and sheets
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Rails for accommodating the withdrawable part
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Base cover optionally available
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Surface treatment
- Steel profiles and sheets galvanized
- Doors and front frame powder-coated
- Switchgear side walls powder-coated
Partitions
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
Compartmentalization
- 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).
Busbars
Busbar mounting
- On commercially available cast-resin insulators
- Busbars bolted, length according to panel width
Compartmentalization
- 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