802-9081.9 • INSTALLATION AND OPERATING INSTRUCTIONS • NXPLUS C • Revision 11 33/293
Description
• Fuse replacement is only possible when the feeder is earthed
• Option for HV HRC fuse-links: "Tripped" indication for remote electrical indication with a
NO contact
Mode of operation If a HV HRC fuse-link operates, the switch is tripped via an articulation which is integrated into
the cover of the fuse box.
Thermal protection If the fuse tripping fails, the sudden overpressure trips the switch via a diaphragm and the
articulation situated in the cover of the fuse box.
The thermal protection works independently of the type and design of the HV HRC fuse-link
used. The thermal protection is maintenance-free and independent of any outside climatic
effects.
Basic scheme of fuse
tripping
The HV HRC fuse-links make SIBA (see page 61, "Selection of HV HRC fuse-links") release the
striker depending on the temperature and trip the switch-disconnector as early as in the
overload range of the fuses. Impermissible heating of the fuse box can be avoided in this way.
9.9 Busbar system
The busbar is single-pole insulated with silicone rubber. Each phase has an earthed layer on
the outside (screened busbar system). This design makes the busbar independent of climatic
effects.
As the busbar system is arranged outside the gas compartment, extension, replacement or
increasing the current carrying capacity by doubling the system is possible within a very short
period of time without requiring any gas work.
To by-pass a removed panel, busbars with double length are available. With these, a defective
panel can be by-passed within a few hours, and switchgear operation can continue.
HV HRC fuse-link in service condition
Fuse tripping through striker of HV HRC fuse-link
Fuse tripping due to sudden overpressure in the
fuse box
Fig. 24: 1250 A busbar system Fig. 25: 1600 A, 2000 A, 2500 A busbar
system
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