Outdoor three-column double-break disconnector

Application

The GW7-72.5D(W) series disconnector is a three-column, horizontally/vertically mounted, double-break, three-phase outdoor AC disconnector (GW7-72.5 type disconnector for short). It is intended for power systems with a rated frequency of 60 Hz and a rated voltage of 72.5 kV: for switching high-voltage lines under no-load conditions, and for electrically isolating or connecting high-voltage busbars, circuit breakers and other high-voltage equipment under maintenance from energized lines. In addition, when the operating mode of the power system changes, it is used for busbar transfer switching with current transfer without breaking or interrupting load current, as well as for making and breaking charging currents of voltage transformers, surge arresters, etc. within specified limits.

Type designation

Compliance with standards

• IEC 62271-102 — High-voltage alternating current disconnectors and earthing switches.

Service conditions

• Ambient temperature: −50 °C … +50 °C.
• Altitude: not more than 2000 m (above 2000 m, the product's suitability can be enhanced on request when ordering).
• Wind pressure: not more than 700 Pa (corresponds to a wind speed of 34 m/s).
• Seismic intensity: not more than 9 degrees.
• Ice coating thickness: not more than 10 mm.
• Environmental pollution degree: III and IV.
• Installation site: free from flammable, explosive and chemically aggressive substances and severe vibration.
• Special service conditions are agreed when ordering.

Product features

The GW7-72.5 is a new-type disconnector developed on the basis of GW7-40.5 technology. It specifically eliminates problems such as porcelain insulator breakage, operating errors, damage and deformation of parts, overheating of the current path and corrosion, in order to improve quality and reliability. The product has a rational design and high performance, including:

1. The conductor tube is made of aluminium angle profile — increased heat dissipation area and improved current-carrying reliability.
2. New-type contacts and externally pressed contact fingers are used. Compared with the previous design, the surface area of the contacts and fingers is larger, heat dissipation is better and the skin effect is eliminated; at the same time, self-cleaning ability and wear resistance are better. The contact enters the fingers deeper than before, which improves current-carrying reliability.
3. Advanced silver plating technology — graphite-silver coating — is used, ensuring the thickness and hardness of the silver layer and significantly improving its adhesion. In addition, adequate contact pressure is created so that the coating does not peel off during long-term operation. The graphite-silver coating extends the service life of silver-plated parts: the contacts withstand more than 10,000 operations.
4. Oil-free self-lubricating bearings and insulating oil-free bearings are used in the rotating units; hot-dip galvanized rod-end bearings are used in the transmission units. All pins are made of aluminium bronze or stainless steel: high corrosion resistance, low rotating torque, small clearances, reliable transmission; corrosion of the main shaft is eliminated and easy rotation is ensured.
5. High-quality materials and surface treatment with high corrosion resistance. For example, all steel parts are hot-dip galvanized or made of stainless steel; all pins are made of aluminium bronze or stainless steel; the non-contact surfaces of the conductor tubes are anodized.
6. The earthing switch is of single-stage design, the earthing moving contact is self-adjusting. Simple and attractive design, low operating force, reliable operation.
7. The vertical rod (connecting the disconnector and earthing switch operating mechanisms to the apparatus) and the horizontal rod (connecting the three phases) are fastened with plates and clamps instead of on-site welding. The horizontal rod of the main conductor tubes of the three phases is connected with right- and left-hand threads, providing stepless adjustment. Eliminating welding and drilling simplifies installation, adjustment, dismantling and repair, and also eliminates corrosion caused by welding.
8. The motor operating mechanism cabinet is welded from stainless steel, the manual operating mechanism cabinet is made of aluminium alloy: attractive appearance, good overall sealing. Motor drive gearbox: good sealing, smooth and quiet operation. The components ensure reliable operation and a full set of interlocking functions.
9. Post insulators with stable characteristics and reliable quality. The reinforcement embedding point in the porcelain has special treatment and a moisture-proof design, ensuring a safety factor of 2.5 for mechanical load. Porcelain manufacturers are carefully selected and acceptance tests are carried out — high quality and reliability of the porcelain.
10. The above-ground part can be supplied as a complete set on request, including hot-dip galvanized steel structures and vertical and horizontal transmission rods.

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