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all about bushing
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TRANSFORM Partner
Dr. Bernhard Heil
HSP Hochspannungsgeräte GmbH & Trench Bushing Group
Design, production and evaluation of the reliability of bushings
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 2
Biography
Engineering Diploma from the RWTH Aachen University, Germany in 2001
PhD from the same University in 2006
From 2006 to 2008 Chief Engineer of the Insulating Systems and Diagnostics
Research Group at RWTH Aachen University
Employed with HSP Hochspannungsgeräte GmbH in Cologne, Germany since
2008
Department Head of the Technical Support
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 3
Agenda
Function of Bushings in the High Electric Field
Description of graded Condenser Bushings
Condenser graded insulating Body (Core)
RBP – Resin Bonded Paper – Properties
OIP – Oil Impregnated Paper – Properties
RIP – Resin Impregnated Paper – Properties
Housings for bushings – Composite Insulators
Transformer Bushings: RIP vs. OIP
Aging of Bushings
Examples
Function of Bushings in the High Electric Field
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 4
Paper
Capacitive grading by conductive layers Equipotential lines
The basic function of a bushing is the save insulation of a conductor by
suitable influencing of the dielectric
Control of electrical field strength inside and outside of the bushing.
The dielectric strength must be ensured for the whole lifetime.
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 5
Description of graded Condenser Bushings
Core insulator
- OIP oil impregnated paper
- RBP resin bonded paper
- RIP resin impregnated paper
Secondary insulation
- Oil (main insulation for OIP)
- Gas
- Dry material filler
Transformer end housing
- Porcelain
- Epoxy-Resin
- RIP (no housing needed)
Outdoor end housing
- Porcelain
- Composite insulator
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 6
Condenser graded insulating Body (Core)
The technology of resin and of oil
impregnated paper bushings at HSP
is established since more than 50 years
RBP-production was
shut down at HSP in 1974.
Some manufacturers do still
hold on for this technology.
START 1913
RBP
SINCE 1960
RIP OIP
SINCE 1950
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 7
RBP – Resin Bonded Paper – Properties
Insulating paper, impregnated with phenolic or epoxy
resin.
Wound under temperature and pressure.
During this process the polymerisation of the resin is
carried out.
Typical laminate material.
Partial discharges with high intensity in several gaps at
normal operating voltage during the whole lifetime.
RBP
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 8
RBP – Resin Bonded Paper – Properties
RBP
Measurement of capacitance and loss factor
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
0 20 40 60 80 100
Temperature [°C]
Lo
ss f
acto
r [%
]
thermal
instability
- Slight temperature dependant loss factor
- Strong increase of the loss factor during lifetime
aging
10 years
15 years
20 years
25 years
30 years max. value
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 9
OIP – Oil Impregnated Paper – Properties
Insulating paper, e.g. cable paper, dried under temperature
and vacuum and impregnated with insulating oil.
Advantages:
- No partial discharge during whole lifetime.
- Good ageing experiences.
- Lower production costs (compared with RIP)
Disadvantages:
- Needs complete housing.
- Core may drop into the transformer if housing is
damaged.
- Inflammable
- max. temperature 105°C
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 10
OIP – Oil Impregnated Paper – Properties
Measurement of capacitance and loss factor
Dissolved gas analysis (DGA), Limits according to IEC 61464:
- Hydrogen (H2) 140 ppm
- Methane (CH4) 40 ppm
- Ethylene (C2H4) 30 ppm
- Ethane (C2H6) 70 ppm
- Acetylene (C2H2) 2 ppm
- Carbon monoxide (CO) 1000 ppm
- Carbon dioxide (CO2) 3400 ppm
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 11
RIP – Resin Impregnated Paper – Properties
Creped insulating paper, dried under temperature and
vacuum, impregnated under vacuum with epoxy resin.
Advantages:
- No partial discharge during whole lifetime.
- Excellent ageing experience.
- No housing for oil end necessary.
- Secondary insulation: Dry material filler
- operates with damaged housing temporarily
- non-inflammable
- max. temperature 120°C
Disadvantages:
- higher production costs
RIP
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 12
RIP – Resin Impregnated Paper – Properties
RIP
Measurement of capacitance and loss factor
- Capacitance and loss factor are temperature-dependent
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 13
RIP – Resin Impregnated Paper – Manufacturing
Impregnation Turning shop
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 14
Housings for bushings - Composite Insulators
In 1980 HSP started to replace porcelain housings with composite insulators.
Design and features of a composite insulator:
- Epoxy resin tube supported with fiber glass as mechanical reinforcement
- On each end of the tube there is a flange made of cast aluminum alloy.
- High hydrophobicity over the whole life time -> Perfect pollution performance
- Surface is Water repellant & self cleaning…even through thick layers of contamination
0
20
40
60
80
100
120
140
160
180
1996 1997 1998 1999 2000 2001 2002 2003
neue Durchführung
new bushing
alte Durchführung
old bushing
Ableitstrommessung / leakage current
I / µA
Long-term measurement of the leakage current
at 2 RIP-123kV bushings running since 1977 in
bad environment.
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 15
Transformer Bushings
Resin impregnated paper (RIP)
bushing with composite insulator
Oil impregnated paper (OIP)
bushing with porcelain insulator
glass fiber reinforced
epoxy resin tube with
silicon sheds
porcelain Insulator
RIP OIP condensor core
SF6 or foam oil secondary
insulation
not necessary epoxi resin oil part end
Option: silicone coated porcelain
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 16
Aging of Bushings
Electrical stress: Overvoltage, VFT
Thermal stress: accelerated aging (ΔT = 6 K bisection of life time)
Mechanical stress
Treeing RBP-bushing Partial breakdown OIP-bushing Partial breakdown RIP-bushing
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 17
3 Gorges, China; RIP ±500kV HVDC
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 18
ITAIPU, Brazil-Paraguay; RIP 525kV EKTG-Bushing
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 19
Yun-Guang, China; RIP ±800 kV UHVDC
Weight: 4 to
Length: 13500 mm
This is the first bushing worldwide for ±800 kV
UHVDC transmission in RIP dry technology.
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 20
Summary
Function of a bushings
Types of condenser cores: RBP – OIP – RIP
Evaluation of the reliability
Manufacturing of RIP
Types of bushings
Aging of Bushings
Examples
07.06.2013 Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group Page 21
HSP Hochspannungsgeräte GmbH & Trench Bushing Group
Our Production Locations Americas Europe Asia
Toronto (CAN)
St. Louis (F)
Troisdorf (GER)
Shenyang (CHN)
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