FKRN12-12D Indoor High Voltage Air-Blast Load Break Switch

Load Break Switch & Fuse Combination Unit

1. Product Overview

The FKN12-12D/T630-20 indoor AC high-voltage load switch is a 12kV, 50Hz three-phase switching device used in medium-voltage distribution systems.

It is designed to:

Switch load current and loop current
Operate no-load transformers and cable charging circuits
Work with a grounding switch for improved safety

The FKRN12-12D/T125-31.5 load switch-fuse combination unit integrates a load switch with a high-voltage current-limiting fuse, enabling safe interruption of overload and short-circuit currents.

The fuse handles short-circuit protection, while the load switch handles normal load switching, working together for full-range protection.

FKRN12-12D Indoor High Voltage Air-Blast Load Break Switch

2. Main Applications

Suitable for 12kV power distribution systems, including:

Ring main units (RMU)
Box-type substations
Urban & rural power grids
Transformer and cable distribution systems
Dual power supply and ring network systems

Functions include:

Load switching
Overload protection
Short-circuit interruption (with fuse unit)

3. Operating Conditions

Ambient temperature: -25℃ ~ +40℃
Altitude: ≤1000m
Relative humidity: ≤95% (daily average), ≤90% (monthly average)
Seismic intensity: ≤8°
Environment: No fire, explosion, chemical corrosion, or severe vibration
Pollution level: Class III

4. Structural Features

Compact integrated design (load switch + grounding switch + fuse optional)
High mechanical and thermal stability
Direct-acting breaking structure for reliable operation
Built-in insulating cover for arc protection inside RMU cabinets
Automatic live-door isolation after opening for enhanced safety
Mechanical interlock system meets “Five Prevention” requirements
Manual or electric operation available (AC/DC compatible)
Supports remote control (SCADA / “three-remote” systems)

5. Main Technical Parameters

Electrical Ratings

Item	Unit	FKN12-12D	FKRN12-12D
Rated Voltage	kV	12	12
Rated Frequency	Hz	50	50
Rated Current	A	630	125
Power Frequency Withstand Voltage	kV	42	42
Isolation Withstand Voltage	kV	48	48
Lightning Impulse Voltage	kV	75	75
Isolation Impulse Voltage	kV	85	85
Load Switch Breaking Current	kA	20	-
Grounding Switch Current	kA	20	20
Short-Circuit Making Current	kA	50	-
Fuse Breaking Capacity	kA	-	31.5
Transfer Current	A	-	1200
Mechanical Life	times	2000	2000
Main Circuit Resistance	μΩ	≤130	≤130

Mechanical Parameters

Item	Value
Fracture Opening Distance	≥175 mm
Phase-to-Phase Distance	210 ± 2 mm
Phase-to-Phase Clearance	≥125 mm
Stroke	210 ± 4 mm
Overstroke	≥40 mm
Closing Asynchronism	≤10 ms
Opening Asynchronism	≤5 ms
Shunt Trip Time	40–65 ms

6. Key Advantages

✔ Reliable 12kV load switching performance
✔ Fuse-assisted short-circuit protection
✔ Compact RMU-friendly structure
✔ Strong mechanical and electrical stability
✔ Safe interlocking “Five Prevention” design
✔ Manual & electric operation options
✔ Suitable for smart grid and remote control systems

FKRN12-12D Indoor High Voltage Air-Blast Load Break Switch