Outdoor three-phase disconnector

General information

GW4 series outdoor disconnectors are designed for installation on lines of outdoor high-voltage switchgear and are used for closing and opening lines that are energised but not under load.

• The disconnector is suitable for operation at altitudes of not more than 4500 m.
• Ambient temperature — not above +40 °C and not below −40 °C.

Note. If the altitude and ambient temperature do not correspond to the above conditions, the possibility of using the disconnector shall be agreed when ordering.

The disconnector is not intended for installation:

• in places with gases or vapours that chemically attack current-carrying parts;
• in places with heavy accumulation of dust;
• in places with fire or explosion hazard;
• in places with severe vibration or shocks (e.g. near electric breaker hammers, excavators, etc.).

Brief description of the GW4 series disconnector design

The GW4 series disconnector is a single-pole, three-column disconnector. In three-phase use, the poles are mechanically interconnected by shafts and operate synchronously.

The GW4 series disconnector consists of a base (frame), insulator columns and a current-carrying part.

Each pole of the GW4 series disconnector has two porcelain columns mounted on bearings at both ends of the base and connected by cross rods; the columns can rotate in the horizontal plane (in the GW4-10 series disconnector, only one porcelain column is mounted on a bearing at one end of the base, while the other is fixed rigidly at the other end).

The current-carrying blade of the GW4 series disconnector is divided into two halves fixed on the tops of the two porcelain columns; they perform closing and opening in the horizontal plane, with the contact point located midway between the columns. The operating mechanism rotates one porcelain column together with the current-carrying part by 91°, and the other column with its current-carrying part is also rotated by 91° via the rods (in the GW4-10 series disconnector, the operating mechanism rotates only the column with the current-carrying part mounted on a bearing at one end of the base, while the other end is fixed). In this way the blade opens or closes to one side.

Main parameters

Service conditions

• Altitude: 4000 m.
• Ambient air temperature: upper limit +40 °C; the lower limit depends on the region: indoors −10 °C, outdoors −30 °C; in cold-climate regions indoors −25 °C, outdoors −40 °C.
• For outdoor products, wind pressure not more than 700 Pa (corresponds to a wind speed of 34 m/s).
• Humidity for indoor products:
  • relative humidity: daily average not more than 95 %, monthly average not more than 90 %;
  • saturated vapour pressure: daily average not more than 2.2×10⁻³ MPa; during periods of high humidity with a sharp drop in temperature, condensation may occur.
• Seismic intensity: not more than 8 degrees.
• Ice coating thickness for outdoor products: 5 or 10 mm.
• Air pollution level: the operating environment of indoor products must not be significantly polluted. The pollution level of the environment for outdoor products is classified as 0, I (normal), II (medium pollution), III, IV (heavy pollution) and is defined by the product specification.
• The air around indoor products must not be noticeably polluted by corrosive or flammable gases, water vapour, etc.; frequent severe vibrations are not permitted.

Note. The minimum nominal specific creepage distance is: for level 0 — 14.8 mm/kV, I — 16 mm/kV, II — 20 mm/kV, III — 25 mm/kV, IV — 31 mm/kV. The specific creepage distance is the ratio of the creepage distance of the external insulation to the highest voltage for equipment.

Service conditions for the humid tropical version (TH)

• Altitude: 4500 m and below.
• Ambient air temperature: annual maximum 40 °C, annual minimum −5 °C, annual average 25 °C; monthly average maximum (warmest month) 35 °C, daily average 35 °C.
• Relative air humidity: maximum average relative humidity of the wettest month 95 % (at 25 °C).
• Maximum rainfall intensity: 6 mm/min.
• Maximum solar radiation intensity: 1.4 cal/(cm²·min) (corresponds to 0.1 W/cm²).
• Maximum black-body surface temperature in direct sunlight: 80 °C.
• Condensation, mould and salt fog are present.

Note. If products are required for conditions beyond the above standards and service conditions, their manufacture is agreed when ordering.

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