ABB djr 00/2 Components USA

ABB djr 00/2 Thermal Considerations when Condenser Bushings Are Applied in Bus Duct

ABB djr 00/2 The Thermal Issues Heat generated in the conductor tube due to flow of current and the electrical resistance of conductor tube Steady state temperature rise at the hot spot is determined by the temperature rise of the hot spot due to the flow of current and by the heat transfer characteristics of the bushing. The heat that is generated within the condenser can only leave the bushing by transfer into the oil or into the air at the terminal ends of the bushing. The heat dissipated at the terminal ends is determined by the temperature of the connecting bus and the surrounding medium (air side and oil side)

ABB djr 00/2 Anatomy of a Condenser Bushing

ABB djr 00/2 l r1r1 r2r2 Field strength between co-axial cylinders: Capacitance of the cylinder configuration: Capacitances in series: Condenser Bushing Fundamentals

ABB djr 00/2 Anatomy of a Condenser Bushing

ABB djr 00/2 Anatomy of a Condenser Bushing

ABB djr 00/2 Test Tap Anatomy of a Condenser Bushing Test Tap Test Tap 450 kV BILVoltage Tap 450 kV BIL

ABB djr 00/2 C 11 C 12 C 13 C 14 C1C1 C2C2 Anatomy of a Condenser Bushing

ABB djr 00/2 Defined in IEEE C , Requirements and Test Procedure for Outdoor Power Apparatus Bushings Section 4.1: Usual Service Conditions Ambient air temperature = 40°C, max; -30°C, min. 24 hour average transformer oil temperature = 95°C External bus connection temperature rise = 30°C max, at rated current. Section 5.4.1: Thermal Basis of Rating Bushing hot spot temperature rise at rated current = 65°C, max, over ambient air temperature. Hottest spot bushing temperature at rated current 105°C = 40°C + 65°C Standard Thermal Conditions for Condenser Bushings

ABB djr 00/2 Defined in IEEE C , Requirements and Test Procedure for Outdoor Power Apparatus Bushings Section 4.1: Usual Service Conditions Ambient air temperature = 40°C, max; -30°C, min. 24 hour average transformer oil temperature = 95°C External bus connection temperature rise = 30°C max, at rated current. Section 5.4.1: Thermal Basis of Rating Bushing hot spot temperature rise at rated current = 65°C, max, over ambient air temperature. Hottest spot bushing temperature at rated current 105°C = 40°C + 65°C Standard Thermal Conditions for Condenser Bushings

ABB djr 00/2 t = 30°C max T = 70 °C 40°C 95°C t = 65°C T = 105°C I = Rated Current Standard Thermal Conditions for Condenser Bushings

ABB djr 00/2 70°C 95°C 40°C Standard Thermal Conditions 105°C

ABB djr 00/2 Thermal Conditions Inside of Bus Duct

ABB djr 00/2 Air side terminal temperature rise can be as much as 65°C according to IEEE C37.23 Ambient air temperature inside of bus duct will, most likely, be greater than the 40°C specified as standard for condenser bushings. 24 hour average transformer oil temperature = 95°C The amount of heat generated within the bushing remains the same. Potential Bus Duct Thermal Conditions

ABB djr 00/2 Air side terminal temperature rise can be as much as 65°C according to IEEE C37.23 Ambient air temperature inside of bus duct will, most likely, be greater than the 40°C specified as standard for condenser bushings. 24 hour average transformer oil temperature = 95°C The amount of heat generated within the bushing remains the same. Potential Bus Duct Thermal Conditions

ABB djr 00/2 t = 65°C, T = 115°C >>40°C 50°C Hot Spot = ?? I = Rated Current Bus Duct Thermal Conditions 95°C

ABB djr 00/2 95°C »» 40°C 50°C not 70°C but t = 65°C T = 115°C Bus Duct vs Free Air t = 65°C T not = 105°C T »» 105°C

ABB djr 00/2 High Temperature Condenser Bushing Developed for Bus Duct Applications Condenser = Nomex (Aramid) insulation + aluminum foils All Seals = high temperature Viton (Fluorocarbon rubber) These materials are suitable for continuous operation at 200 °C

ABB djr 00/2 Why Not Solid Bushings Performance (Corona and / or Temperature) and Cost

ABB djr 00/2 Why Not Solid or Bulk Bushings ABB Solid Bushing Types Type RJ Type LCRJ Type A

ABB djr 00/2 ABB Solid Bushing Comparison

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