The FZRN21-12D/T125-31.5 Type Indoor High-Voltage Vacuum Load Switch (Combination Device), also known as the ZFN21 Vacuum Load Switch, is a front-mounted, wall-mountable vacuum load switch (including wall-hung type). Equipped with fuses and an earthing switch, it boasts advantages such as high breaking capacity, safety and reliability, long electrical life, frequent operation capability, compact structure, small size, light weight, and almost no maintenance requirements.
It provides overload protection for transformers and prevents phase-loss operation of equipment. Featuring a visible isolating fracture, it can be equipped with a closing-capable earthing switch and an electric spring mechanism. Its remote control and telemetry performance meets the requirements of GB 3048-1990 "AC High-Voltage Load Switches for 3-63kV" , IEC 420 "AC High-Voltage Load Switch-Fuse Combination Devices" international standard, and GB 16926-1997 "AC High-Voltage Load Switch-Fuse Combination Devices" .
The load switch offers advantages including compact structure, small size, light weight,capability to close rated short-circuit current, safety and reliability, long electrical life, frequent operation capability, and almost no maintenance needs.
The combination device provides overload protection for transformers and prevents phase-loss operation of equipment.
Both the load switch and the combination device are equipped with a closing-capable earthing switch and a visible isolating fracture. They can be fitted with an electric spring mechanism to achieve remote control operation, and this product is configured with the CT21 type spring operating mechanism.
The load switch and combination device are suitable for 50Hz AC networks with a rated voltage of 12kV, used for breaking load current and overload current. Additionally, the combination device has the function of breaking rated short-circuit current.
They can be used in complete power distribution equipment such as ring network switchgear and combined distribution stations, and are widely applied in urban power grid construction and renovation, industrial and mining enterprises, high-rise buildings, and other public facilities. Serving as ring network power supply and terminal equipment, they play roles in power distribution, control, and protection of electrical equipment. They are particularly suitable for oil-free, maintenance-free, and frequent operation scenarios.

Model Designation Explanation