FZN25‑12D Indoor High‑Voltage Load Switch‑Fuse Combination Unit

Overview

FZN25‑12D vacuum load switch and FZRN25‑12D combination unit are mainly applied in 12 kV, 50 Hz three‑phase AC ring‑network or terminal‑power‑supply urban distribution substations and industrial power‑consuming equipment for load control and short‑circuit protection. The load switch can make and break load current, ring‑network current, no‑load transformer current and cable charging current. The combination unit is capable of breaking any current up to the rated short‑circuit current.

It adopts interlocked direct‑acting isolating break and vacuum interrupter, with both manual and motor‑operated functions.

Thanks to the unique transmission mechanism of FZN25 / FZRN25 series, the interrupter withstands voltage only at the instant of closing and opening, which enables compact dimension and competitive cost.

FZN25 and FZRN25 can complete operation for isolating break and interrupter break in one single stroke.

Between static contact and moving conductive cylinder of FZN25 / FZRN25, there is an interlocking shutter linked with earthing switch, ensuring safety and convenient maintenance.

Operating / Environmental Conditions

FZN25‑12D indoor AC high‑voltage vacuum load switch and FZRN25‑12D indoor AC high‑voltage vacuum load switch‑fuse combination unit are control‑and‑protection devices for 12 kV, 50 Hz three‑phase AC distribution systems. Oil‑free, non‑toxic, free of fire and explosion hazards, they are widely used in industrial‑mining enterprises and urban‑building distribution substations. For electrical equipment such as transformers, the combination unit provides more reliable protection than circuit breakers. It is especially suitable for ring‑network, double‑radial power‑supply units and box‑type substations.

Service environmental conditions:

a) Ambient air temperature: upper limit +40 °C; lower limit ‑25 °C (‑30 °C allowed for transportation and storage)

b) Altitude: ≤ 1000 m

c) Relative air humidity: daily average ≤ 95 %, monthly average ≤ 90 %

d) Seismic intensity: not exceeding Grade 8

e) Ambient air shall not be significantly polluted by corrosive / flammable gas, water vapor, etc.

f) No frequent severe vibration

g) Pollution degree: II

Additional operating‑condition summary:

‑ Altitude: ≤ 1000 m

‑ Ambient temperature: ‑25 °C ~ +40 °C

‑ Relative humidity: daily average ≤ 95 %, monthly average ≤ 90 %

‑ Sites free of conductive dust, corrosive gas and water vapor

‑ Sites without severe vibration

‑ Pollution degree: II