BUSHING TYPE OIL IMMERSED CURRENT TRANSFORMERS

Frequency

• 50 Hz, 60 Hz

Secondary Current

• 1 A, 2 A or 5 A, others on request.

Primary Current

• up to 4000 A

Thermal and Dynamic Ratings

• Short time thermal current ratings up to 50 KA/ 3 sec and dynamic current ratings up to 125 KA peak.

Continuous Thermal Current

• 1.2 x In continuous (up to 2.0 x In or higher on request).

Insulation

• Oil impregnated paper, high dielectric strength, low dielectric losses.

• Graded layers with well rounded edges enable a uniformly distributed field over the whole unit.

Insulating Oil

• The insulating oil is mineral oil in conformity with IEC 60296.

• Before impregnation, moisture and gases are removed from the oil by special processes.

• Drain plug for taking samples and oil refilling facilities are provided on request.

• Floating type oil level indicator is standard supply.

Oil Impregnation

• Heat and vacuum are applied to the fully insulated windings after assembly of the current transformer for drying purposes, followed immediately by the oil impregnation procedure.

Hermetic Seal

• Oil volume variations are compensated with stainless steel bellows placed in the head of the transformers. With this facility there will be no contact between air and oil in the transformers.

• The dielectric strength will remain unchanged for the life time of the CT.

Bushings

• Brown, Grey glazed porcelain or polymer.

Primary Terminals

• Primary terminals are made from tin plated copper or aluminium.

• Vertical and horizontal primary terminals are available.

• Dimensions depend on rated primary current.

• Stud, nema pad or clamp type primary terminals are available.

Cores

• Grain oriented silicon steel is used.

• The core shapes are toroidal with or without air gap.

• Electrolytic copper suitable to withstand rated continuous current and short time thermal current is used for primary winding.

• Enamelled electrolytic copper wire is used for Secondary winding.

Bracelets

• All bracelets used on transformers are made from aluminium alloy.

Head

• The housing head is fabricated from corrosion protected aluminium.

• Every housing is subject to pressure and vacuum test before assembly.

Base Plate

• Base of the transformers are fabricated from steel and galvanised.

Name Plate

• Name plates are stainless steel and weatherproof.

Secondary Terminal Box

• Hinged type boxes are used and are sealable on request. They are made of galvanized steel or stainless steel.

• Clamp type secondary terminals are used. Other secondary terminals are available on request. Earthing

• Earthing terminals are located on the base of the transformers.

• Clamp type terminals are available on request.

Painting

• External surface of the transformers, which are already corrosion protected, are additionally painted grey. Other colours are available on request.

Earthquake Design

• Standard design is up to 0.6g.

Ambient Temperature

• Standard design is suitable for temperature range -50 °C to +50°C. Other ranges on request. Mechanical Strength

• Applied load to the primary terminal in horizontal and vertical is in conformity with related IEC standards.

Altitude

• Standard design is suitable up to 1000 m above sea level.

Optional Accessories

• Capacitive tap

• Steel support structure

• Primary connectors

• Marshalling box

Maintenance

• Maintenance free, simple recommendations;

• Clean the porcelain bushing at regular intervals depending on the degree of pollution.

• Ensure that there is no oil leakage.

Spare Part & Special Tools

• There are no user serviceable parts, therefore no spare parts or special tools are required for maintenance.

Assembly

• Before the assembly, following visual checks should be made;

• There are no oil leaks,

• The porcelain is not damaged,

• The aluminium protective cover on the bellows is not damaged,

• There is no damage on the primary terminals,

• The oil level indicator indicates sufficient oil level.

Packing

• The transformers are packed in rugged wooden crates which are suitable for overseas transportation.

• The transformers are encapsulated in polyethylene covers to keep them from environmental effects.

• Wooden crates can be lifted by either a fork lift or by a crane with slings.

• Other technical specifications may be available upon request.