Introduction
The LK-VLBS is a three phase vacuum interrupter switch with a
high breaking capacity.
Application
It was primarily designed for power networks and substation systems
where it could replace vacuum circuit breakers in selective applications.
Description of functions
On each phase, a vacuum interrupter performs the function
of arc quenching. The vacuum interrupter is housed in an insulating
shield. This reduces the size of the switch so that it can be
housed in panels of sizes as small as 470mm wide x 900mm deep
x 1900mm high.
The LK-VLBS is also built to house HV HRC fuses. A stored energy
mechanism on the LK-VLBS allows for shunt tripping and fuse triggered
tripping. Hence, with fuses the LK-VLBS can achieve up to 50 kA
in short circuit breaking capacity. With fuses, the speed of interruption
can reach times of less than 10 ms, depending on the time/current
characteristic of the fuse selected.
The vacuum interrupter switch when controlled by a current protection
relay unit protects for overload and fault currents up to 20kA.
Furthermore when used in combination with HV HRC fuses the fuses
act as backup devices for fault current levels of up to 50 kA.
In the event of overloading, the current protection relay triggers
the switch so that the vacuum interrupter, in place of the fuse,
breaks the current. This overcomes the traditional shortfall of
relying soley on fuses for overload protection whereby fuses are
relatively insensitive towards small overload.
During short circuit, either the interrupter or the fuse breaks
the current, depending on the current level. Selective discrimination
between the fuse and the vacuum interrupter is achieved by coordinating
the time/current curves of the relay and the fuses. Thus with
the fuse combination double protection of downstream equipment
is achieved, making the LK-VLBS superior as a choice for overload
and fault protection equipment.
Manufacturing and Endurance
Components for the three-phase operation are mounted
on a chasis which also mounts an optional isolator on the incoming
end and a fault-making earth switch on the out going end of the
interrupter. These last two components are interlocked in an opposed
operating sequence towards each other and at the same time interlocked
with the vacuum interrupter to ensure proper operating sequence.
The LK-VLBS is capable of interrupting fault current levels up
to 20kA through the vacuum interrupter when the switch is controlled
by a current protection relay system.The LK-VLBS interrupts short
circuit currents at within less than 50ms of fault detection (excluding
the processing time of the relay.).
Like other vacuum switches, LK-VLBS have a high electrical enduarance
of more than 10,000 times, and virtually maintainence free.
Performance Data
Physical Appearance and Schematic of the Vacuum Switch
Standards
- Conforms to IEC 60298 for sealed Switchgear
- Conforms to IEC 60420 for load break circuit with fuses
- Conforms to IEC 60265 for load break switches
- Conforms to IEC 60129 for earthing switches
Design and Materials used for the LK-GLBS (SF6 Switch)
Dielectric field distribution and current leakage between incoming
and outgoing terminals are controlled by large creepage distances,
bushings and by an internal earth grid to provide safety and protection
to service personnel.
The load break switch is mounted within the insulation casing
of epoxy resin. During the opening operation, the LK-GLBS interrupts
the current by the rotary and puffer action of the SF6 gas on
the arc.
The three positions of the switch are realised by rotating the
moving contact/air piston on a unic shaft.
The spring charged mechanism can be motorised. The LK-GLBS is
compatible with standard cable bushings and HRC fuses for 12 kV
and 24 kV applications.
Capacity and Testing of the LK-GLBS (SF6 Switch)
The switch is capable of interrupting currents up to 630A at 12
kV when operating without SF6, i.e., in air. The LK-GLBS can be
fitted with fuse holders to function as a fuse switch with tripping
trigged by blowing of the fuses.
The LK-GLBS is arc-proof tested.The over pressure valve is integrated
in the structure of the shell and realises the arc proof function.
The LK-GLBS is a compactly designed switch that can be housed
in a panel by the dimensions of 370mm x 950mm x 1650mm (W x D
x H).
Technical data for the LK-VLBS Vacuum switch
Additional Literature
Download the Products Catalog here.
Other Medium Voltage Products
Air puffer Load Break Switch
Sulfur Hexaflouride (SF6) Load Break Switch
Back to Medium Voltage Products
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