FKN12-12RD/630A Wall-mounted High-voltage Load Switch, 10KV Fuse Combination Load Switch

The FKN12 series load switch is a combined high-voltage switchgear with a rated voltage of 12kV and a frequency of 50Hz, mainly used in scenarios such as switching load currents, controlling no-load transformers, and operating overhead lines in power systems.

I. Main Models and Functions

This series includes two main models:

FN12-12D/630-20 type indoor AC high-voltage load switch: With a rated current of 630A, it has the capability to switch load currents, closed-loop currents, no-load transformers, and cable charging currents, and can close short-circuit currents. Equipped with an earthing switch, it can withstand short-circuit currents.

FN12-12R.D/100-31.5 type (or FKN12 series) indoor high-voltage load switch-fuse combination apparatus: Combines a load switch with a high-voltage current-limiting fuse to achieve full-range current interruption. The load switch is responsible for interrupting operating currents, and the fuse is responsible for interrupting short-circuit currents. The two work together to handle any overcurrent between operating currents and short-circuit currents.

II. Core Structure and Technical Features

Combined structure: The equipment integrates the load switch, high-voltage current-limiting fuse, and mechanism on a single frame, with a compact structure.

Interruption method: Adopts a vacuum interrupter or puffer-type design, with vertical linear movement for interruption and closing. The arc is extinguished inside a bell-shaped insulating cover, which can prevent a reduction in insulation strength between phases or to ground.

Operating mechanism: Uses a spring energy-storage operating mechanism to ensure stable opening and closing speeds, unaffected by operating force. Supports dual-mode operation: manual and electric (AC/DC compatible).

Safety interlocks: Reliable mechanical interlock devices are installed between the load switch, earthing switch, and fuse, meeting the "five preventions" requirements for preventing misoperation.

Contact material: Uses copper-tungsten alloy arc contacts and plum-blossom-shaped main contacts to enhance conductive reliability and electrical lifespan.

Intelligent functions: Some models have "four remote" functions such as remote monitoring, data detection, and fault diagnosis. The built-in multi-functional power quality meter can measure more than 52 electrical parameters and is applied in new energy power grid connection fields such as photovoltaics and wind power.

III. Technical Parameters

Rated values: Rated voltage 12kV, rated frequency 50Hz. The rated current of the load switch is 630A, and the rated current of the fuse in the combination apparatus is commonly 125A.

Interruption capacity: The rated short-time withstand current of the load switch is 20kA, and the rated short-circuit closing current is 50kA. The rated short-circuit interruption current of the fuse in the combination apparatus is 31.5kA.

Mechanical performance: Mechanical lifespan is 2000 operations, and the main circuit resistance is ≤300μΩ.

IV. Application and Environmental Requirements

Main applications: Suitable for three-phase distribution systems of 12kV and below, serving as control and protection for equipment such as transformers, cables, and overhead lines. It is especially suitable for terminal substations, box-type substations, and ring network power supply units in urban and rural power grids.

Environmental conditions: Normal operating ambient temperature ranges from -25℃ to +40℃, and the altitude does not exceed 1000m. The surrounding air should have no significant corrosive or flammable gas pollution.

Installation requirements: Must be installed vertically, and the switch frame, operating mechanism, cable sheath, etc., must be reliably grounded (series grounding is prohibited).

V. Use and Maintenance Precautions

The fuse melt connected in series with the load switch must be properly selected to ensure that the melt blows first when the fault current exceeds the interruption capacity of the load switch.

Before operation, several no-load opening and closing operations should be performed to check that there is no jamming in the rotating parts, that the closing is in place, and that there is sufficient safety distance after opening.

During inspection, check for dirt, cracks, and discharge phenomena on the insulators. The switch body must not be washed with water.

After the fuse blows and triggers opening, three-phase fuses of the same model and specification must be replaced.

The product should be stored in a ventilated, dry room without corrosive gases, and must be protected from rain and direct sunlight.