Upload
jamir-coombes
View
220
Download
4
Tags:
Embed Size (px)
Citation preview
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
r1r2
• Field strength between co-axial cylinders:
• Capacitance of the cylinder
configuration:
• Capacitances in series:
)/(ln
1)(
12 rr
U
rrE
)/(ln
2
12 rr
lC
n
i iCC 1
11
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 BIL Voltage Tap 450 kV BIL
ABB djr 00/2
C11
C12
C13
C14
C1
C2
Anatomy of aCondenser Bushing
ABB djr 00/2
• Defined in IEEE C57.19.00, 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 current105°C = 40°C + 65°C
Standard Thermal Conditions for Condenser Bushings
ABB djr 00/2
• Defined in IEEE C57.19.00, 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 current105°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 CurrentStandard 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 ofBus 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 DuctThermal Conditions
95°C
ABB djr 00/2
95°C
»» 40°C 50°C
not 70°C but t = 65°CT = 115°C
Bus Duct vs Free Air
t = 65°CT not = 105°CT »» 105°C
ABB djr 00/2
High Temperature Condenser BushingDeveloped 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
ABBComponents USA