KOTEF
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INSTRUMENT TRANSFORMERS PRODUCT S OLUTIONS KOTEF Combined CT/VT 72.5 to 420 kV The KOTEF is designed to provide both current and voltage measurements from a single device. Design and advantages As with separate transformers, the current transformer part is located in the head housing and the voltage transformer part in the base tank. The bushings between high-voltage potential and ground potential are arranged in opposite directions inside the insulator. The base dimensions remain the same as a voltage transformer of the same nominal voltage. The CT and VT functions are fulfilled within a single unit. KOTEF utilizes the same components as the individual CTs and VTs. Both transformers are combined in a single metering unit and are available in porcelain or composite. This is an excellent solution for adding metering capability to either a new substation installation or a site being upgraded where space is at a premium. Conseguently, considerable cost savings are realized in the initial purchase price, transportation, real estate and installation labor and materials compared to the eguivalent costs of two separate transformers. The KOTEF Line combines the advantages and design features of the O SKF and OTEF lines. MAIN FEATURES LONG SERVICE LIFE AND NEAR Metering and protection Characteristics: - High guality paper-oil insulation - Oil expansion and hermetic seal by stainless steel diaphragm bellows - Oil level indicator - Cores in heavy walled aluminum housing - Changing of primary ratio by primary connection (single, double or guadruple ratio) orbysecondarytaps S eismic designs available Compliance with ANSI/IEEE standards, other standards on reguest. ZERO MAINTENANCE Insulation integrity is assured by the fact that the oil is hermetically sealed from the atmosphere by a metallic diaphragm assembly. All external parts are of corrosion-resistant material. Therefore, regular painting is not reguired. KOTEF have been designed for a 30 years plus lifetime. CUSTOMER BENEFITS • Price advantage • Space savings: only one base • Cost savings on transportation and installation • Reduction in Inventory • Protection against bursting • Maintenance-free

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CURRENTTRANSFORMER DESIGN Head type design, with active parts in the head. The primary is normally a straight bar type conductor with low inductance. Therefore primary surge protection is not re q uired. Ratio change can be accomplished either by primary bar series-parallel connection (single, double or q uadruple ratio) or by secondary taps. Combinations of series-parallel connection and secondarytaps are also possible. The head type design also has the advantage of spreading the primary flux uniformly and symmetricallythrough the cores, avoiding local saturation and reducing the leakage...

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HIGH QUALITY INSULATION The insulation paper is applied mechanically, guaranteeing a homogenous, high-density paper insulation. Defined grading layerswith field-optimized electrode rings achieve a uniform field distribution along the insulator between line and ground. Most of the insulation is from Kraft paper. The coil insulation is a closed style design resulting in a compact unit with good dielectric withstand characteristics. Surge arrestors to protect the KOTEF are not necessary. High quality mineral oil with excellent aging stability and gas-absorbing properties is used. The oil...

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COMBINED CT/VT PRODUCT SOLUTIONS KOTEF DIMENSIONS Except the ERCT line current transformers are for specific projects custom made products. The following dimensions refer to certain standard versions. Other requirements might effect the dimensions. The b ase tank size can vary b ased on transformer output requirements and/or frequencies less than 60 Hz. The head size ofthe CT portion depends on the ratings of the cores, the primary current and the thermal short-time current. Other head sizes and longer creepage distances can b e provided. Maximum system voltage (Um) kV_72.5_123_145_170...

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KOTEF
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