Design, production and evaluation of the reliability of bushings
Dr. Bernhard Heil
HSP Hochspannungsgeräte GmbH & Trench Bushing Group
TRANSFORM Partner
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
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
Page 2
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
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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Function of Bushings in the High Electric Field
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.
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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Description of graded Condenser Bushings
Core insulator
- OIP oil impregnated paper
- RBP resin bonded paper
- RIP resin impregnated paper
Transformer end housing
- Porcelain
- Epoxy-Resin
- RIP (no housing needed)
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
Secondary insulation
- Oil (main insulation for OIP)
- Gas
- Dry material filler
Outdoor end housing
- Porcelain
- Composite insulator
07.06.2013
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Condenser graded insulating Body (Core)
RBP
START 1913
RBP-production was
shut down at HSP in 1974.
Some manufacturers do still
hold on for this technology.
OIP
RIP
SINCE 1950
SINCE 1960
The technology of resin and of oil
impregnated paper bushings at HSP
is established since more than 50 years
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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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.
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
RBP
07.06.2013
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RBP – Resin Bonded Paper – Properties
Measurement of capacitance and loss factor
- Slight temperature dependant loss factor
Loss factor [%]
- Strong increase of the loss factor during lifetime
2,4
2,2
2
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
aging
max. value
RBP
thermal
instability
30 years
25 years
20 years
15 years
10 years
0
20
40
60
80
100
Temperature [°C]
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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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
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
Page 9
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)
-
Carbon monoxide (CO) 1000 ppm
-
Carbon dioxide (CO2)
2 ppm
3400 ppm
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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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
RIP
Disadvantages:
-
higher production costs
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
Page 11
RIP – Resin Impregnated Paper – Properties

Measurement of capacitance and loss factor
- Capacitance and loss factor are temperature-dependent
RIP
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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RIP – Resin Impregnated Paper – Manufacturing
Impregnation
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
Turning shop
07.06.2013
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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
Ableitstrommessung / leakage current
180
160
I / µA
neue Durchführung
new bushing
alte Durchführung
old bushing
140
120
100
80
60
40
20
0
1996
1997
1998
1999
2000
2001
2002
2003
Long-term measurement of the leakage current
at 2 RIP-123kV bushings running since 1977 in
bad environment.
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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Transformer Bushings
Oil impregnated paper (OIP)
bushing with porcelain insulator
Resin impregnated paper (RIP)
bushing with composite insulator
Option: silicone coated porcelain
porcelain
OIP
Insulator
condensor core
glass fiber reinforced
epoxy resin tube with
silicon sheds
RIP
oil
secondary
insulation
SF6 or foam
epoxi resin
oil part end
not necessary
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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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
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
Partial breakdown RIP-bushing
07.06.2013
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3 Gorges, China; RIP ±500kV HVDC
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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ITAIPU, Brazil-Paraguay; RIP 525kV EKTG-Bushing
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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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.
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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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
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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HSP Hochspannungsgeräte GmbH
& Trench Bushing Group
Our Production Locations
Americas
Europe
Asia
Troisdorf
(GER)
Toronto (CAN)
Shenyang (CHN)
St. Louis (F)
Dr. Bernhard Heil, HSP Hochspannungsgeräte GmbH & Trench Bushing Group
07.06.2013
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