FK(R)N12-12 High Voltage Air Load Breaker Fuse Switch

The FKN12-12D load switch and FKRN12-12D switch-fuse combination are designed for 12kV three-phase distribution systems, suitable for transformer, cable, and line control. With rated currents of 630A (FKN) and 125A (FKRN), they feature high insulation, spring-operated mechanisms, and reliable arc extinction in bell-shaped covers. Compact and interlocked, they offer 2000 mechanical operations and withstand harsh environments (–25°C to +40°C, ≤2000m). Ideal for substations and ring networks, these GB/T and IEC-compliant switches ensure safe load switching, overload protection, and short-circuit interruption in urban and industrial applications.

product details

Type & Meaning

1	Rated short-time withstand current (kA)
2	Rated current (A)
3	Spring mechanism
4	Earthing switch (optional)
5	Rated voltage (kV)
6	Design No.
7	Indoor
8	Air medium
9	Load switch

1	Rated short-circuit breaking current (kA)
2	Rated current of the maximum fuse equipped (A)
3	Spring mechanism
4	Earthing switch (optional)
5	Rated voltage (kV)
6	Design No.
7	Indoor
8	With fuse holder
9	Air medium
10	Load switch

Ambient conditions

1)Ambient temperature: within -25℃~+40℃;
2)Altitude: ≤ 2000m;
3)Ambient humidity: daily mean relative humidity ≤ 95% and monthly mean ≤ 90%;
4)Seismic intensity: ≤ Ms8;
5)Anti-fouling level: Class Ⅱ;
6)The operation site should be free of flammable or explosive danger, no water vapor or chemical corrosive gas, no violent vibration.
Note: Please negotiate with the manufacturer if beyond the above-mentioned environmental conditions.

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Technical Parameters

☆ Technical parameters of FKN12-12D series switch and FKRN12-12D series switch-fuse combinations are shown in Table 1

No.	ltem			Unit	FKN12-12D	FKRN12-12D
1	Rated voltage			kV	12	12
2	Rated frequency			Hz	50	50
3	Rated current			A	630	125
4	Rated insulation level	1min power-frequency withstand voltage	To-ground, phase-to-phase	kV	42	42
		1min power-frequency withstand voltage	lsolating distance		48	48
		Lightning impulse withstand voltage (peak)	To-ground, phase-to-phase		75	75
		Lightning impulse withstand voltage (peak)	lsolating distance		85	85
5	Rated short-time withstand current (kA)		Load switch	kA	25
5	Rated short-time withstand current (kA)		Earthing switch	kA	20
6	Rated short-circuit duration (short-time withstand time)		Load switch	S	4
6	Rated short-circuit duration (short-time withstand time)		Earthing switch	S	2
7	Rated short-circuit making current (peak)				50
8	Rated breaking current		Active load breaking current	A	630
			Closed loop breaking current		630
			Cable charging current		10
			Breaking capacity of no-load transformer	kVA	1250
9	Rated short-circuit breaking current (current-limit fuse)			kA		31.5
10	Rated transfer current			A		1200
11	Mechanical endurance			time	2000	2000

☆ Mechanical properties are shown in Table 2

No.	ltem	Unit	Parameter
1	Isolating distance	mm	≥175
2	Phase-to-phase central distance		210±2
3	Phase-to-phase air clearance		≥125
4	Travel		210±4
5	Overtravel		≥40
6	Out of simultaneity of three-phase closing	ms	≤10
7	Out of simultaneity of three-phase opening		≤15
8	Inherent opening time of shunt release		40~65
9	Main circuit resistance	μΩ	≤130

☆ For the current-limiting fuse in the switch-fuse combinations, the rated current of the fuse-link is selected based on the transformer capacity, and the reference parameters for selection are shown in Table 3