FK(R)N-12 Load Break Switch and Combination Appliance

FK (R)N12-12 type indoor AC high-voltage load switch (fuse combination) is a three-phase high-voltage switch with rated power of 12KV and rated frequency of 50Hz, which is suitable for distribution offices and substations of industrial and mining enterprises. It is used as the protection and control of electrical equipment for dividing load current, closed-loop current, no-load transformer and cable charging current. Hybrid short-circuit current. Load switches equipped with ground switches can withstand short-circuit current. Equipped with manual and motor operating mechanism, easy to achieve the power system engineering three remote control requirements.

1. Ambient Temperature

Normal operation: -25°C to +40°C

24-hour average: ≤ +35°C

Storage and transportation temperature: Short-term exposure to -30°C

2. Altitude

≤ 1000 m (Special design required for higher altitudes)

3. Relative Humidity

Daily average: ≤ 95%

Monthly average: ≤ 90% (No condensation)

4. Pollution Level

Class II (No corrosive or explosive gases, and no severe dust)

5. Vibration and Seismic Activity

No frequent or severe vibration

Seismic intensity: ≤ 8 degrees

6. Installation Location

Indoor, dry, well-ventilated, protected from rain and snow

Suitable for standard enclosures such as the HXGN-12 ring main unit

7. System Conditions

Rated voltage: 12 kV

Rated frequency: 50 Hz (some models support 60 Hz)

I. Operating Principle (Compressed Air Arc Extinguishing + Spring Energy Storage Mechanism) The FK(R) N12-12 is a 12kV indoor

compressed air load switch (FKRN is a combination switch with fuse). Its core mechanism is spring energy storage + compressed air arc extinguishing. It can switch load current, unloaded transformer and cable charging current, but cannot independently interrupt short-circuit current (which is cut off by the fuse).

1) Mechanism Principle (Four-bar linkage + Spring Energy Storage) Manual/Electric Operation → Main shaft rotation → Four-bar linkage drives the contacts and compressed air piston. Closing: Turn the handle clockwise approximately 127° → Closing spring stores energy → Releases energy at dead point → Quick closing. Opening: Turn the handle counterclockwise → Unlocks the opening spring → Quick opening; or electric tripping, fuse impact tripping. Interlocking: Forced interlocking between load switch, grounding switch, and cabinet door to prevent misoperation.

2) FKRN Combined Electrical Appliance Principle Load Switch: Opens and closes normal load/overload current. Fuse: Breaks short-circuit current; if any phase fuses → impactor actuates → linked load switch opens, achieving three-phase isolation.2) Mechanism Principle (Four-bar linkage + Spring Energy Storage) Manual/Electric Operation → Main shaft rotation → Four-bar linkage drives the contacts and compressed air piston. Closing: Turn the handle clockwise approximately 127° → Closing spring stores energy → Releases energy at dead point → Quick closing. Opening: Turn the handle counterclockwise → Unlocks the opening spring → Quick opening; or electric tripping, fuse impact tripping. Interlocking: Forced interlocking between load switch, grounding switch, and cabinet door to prevent misoperation. 3) FKRN Combined Electrical Appliance Principle Load Switch: Opens and closes normal load/overload current. Fuse: Breaks short-circuit current; if any phase fuses → impactor actuates → linked load switch opens, achieving three-phase isolation.

II. Standard Operating Procedure (Manual, Most Commonly Used) 🔒 Safety Prerequisites Wear insulated gloves and shoes; ensure there are no foreign objects inside the cabinet and that grounding is reliable. Before operation, verify the circuit number and status(open/closed); it is strictly forbidden to operate the grounding switch under load.

(1)Closing Operation (Load Switch → Running) Confirmation: Load switch open, grounding switch open, cabinet door closed and locked. Insert Handle: Insert the dedicated operating handle into the load switch main shaft hole. Rotate clockwise: approximately 127°, feel the "energy storage → passing dead point → rapid closing" action, and hear the closing sound. Confirmation: The indicator shows "closed," the contacts are in place, and there are no abnormal sounds. Remove the handle; completed.

(2) Opening Operation (Load Switch → Isolation) Confirmation: The circuit is unloaded (no load current). Insert Handle: Insert into the load switch main shaft hole. Rotate counterclockwise: Unlock the opening spring, quickly open, and hear the opening sound. Confirmation: The indicator shows "open," and there is a clear break. Remove the handle; completed.

(3) Grounding Switch Closing (Maintenance/Safety Grounding) Confirmation: Load switch is tripped, indicator "Off". Insert handle: Insert into the grounding switch main shaft hole. Rotate clockwise: After reaching the correct position, indicator "Close", three-phase reliable grounding. Remove handle; the cabinet door can now be unlocked (interlock released).

(4) Grounding Switch Opening (Resumption of Operation) Confirmation: Cabinet door closed and locked. Insert handle: Rotate the grounding main shaft counterclockwise → indicator "Off". Remove handle; the load switch can be closed again.

(5) Electric/Remote Control Operation (Optional) Closing: Electric mechanism stores energy → receives closing command → automatically completes closing and stores energy. Opening: Electric tripping or protection action → automatic opening; fuse blowing will also trigger opening.

   Figure 1 Formal installation on the right side

Figure2 Formal installation on the left  side

Remark:

1. In addition to the above two standard shapes, FKRN12-12 series can be installed upside down according to the actual use;

2. FKRN12-12 can also cancel the grounding knife, or fuse.

 Figure 3: Electric operation wiring diagram

                                                                                                                                                          Figure 4: Manual operation wiring diagram

Introduction and Location
Founded in 2014, Shaanxi West Power Tongzhong Electrical Co., Ltd. is a leading innovator in the electrical industry with over 20 years of industry experience. Strategically located at No. 1 East Gaoxin Avenue in the High-Tech Development Zone of Baoji City, Shaanxi Province, our prime location offers excellent connectivity through expressways and high-speed railways. This advantageous location allows us to efficiently serve both domestic and international markets, ensuring fast response times and seamless logistics.

Our Mission and Vision
Since our founding, we have been driven by a mission to revolutionize power transmission and distribution systems. Our vision is to expand our international market share and establish our VTZ brand as a symbol of quality and innovation in the electrical industry. We are committed to becoming a global leader, known for our dedication to advancing technology, ensuring quality, and prioritizing customer satisfaction.

 

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