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25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens
Medium-Voltage Switchgear - Then and Now -
Hans-Joachim Müller
Power Transmission and Distribution
© Siemens AG 2006
Page 2 June 07 Medium Voltage Division
Evolution of Medium-Voltage Switchgear
non type tested
Air-insulated
type tested
Gas-insulatedAir/solid-insulated Cast-resin insulated
Source: ABB
Local installation
Workshop manufacture
Factory-assembled,type-tested
Factory-assembled,
compact
Factory-assembled,
SF6-insulated
Year until 1950 until 1970 since 1970 since 1980 since 1982
Building 83 m3 47 m3 29 m3 24 m3 8 m3
Panel 19 m3 14.5 m3 8.7 m3 5.8 m3 2.2 m3
Power Transmission and Distribution
© Siemens AG 2006
Page 3 June 07 Medium Voltage Division
Situation in the Past
Yesterday, switchgear were air, oil or cast-resin insulated with the following features:
Huge dimensions Dependent on pollution and climate Maintenance at regular intervals Human failure during maintenance High fire risk Not arc-fault tested
This means:
High investment for buildings High costs for maintenance staff and system
transfer in the network Breakdown of the network (longer downtimes)
Power Transmission and Distribution
© Siemens AG 2006
Page 4 June 07 Medium Voltage Division
Restricted Availability and Reliability of Supply
After short circuit at the rear side of an epoxy-resin insulated switchgear
Burned-out 10 kV substation: Fire after short circuit in an epoxy-resin insulated ring-main unit
Power Transmission and Distribution
© Siemens AG 2006
Page 5 June 07 Medium Voltage Division
Requirements for development:
Personal safety
Reliability of supply
Maintenance-free design
Suitability for all switching duties
Sufficient power reserves
Low fire risk
Small, light design
Concept options for new switchgear due to availability of the following equipment:
Maintenance-free switching devices
Shockproof cable plugs and bar connections
Electronic measuring and protection devices
Objectives for the Development of New Switchgear
Power Transmission and Distribution
© Siemens AG 2006
Page 6 June 07 Medium Voltage Division
Constructional implementation:
Solid insulation is replaced by insulating gas with constant properties
Sealed enclosure of primary part
Installation of fixed-mounted, maintenance-free switching devices:- Vacuum circuit-breaker- Three-position switch- SF6-switch-disconnector
Shockproof cable plugs
Use of current and voltage transformers with low susceptibility to faults
Verification of safe isolation from supply with capacitive voltage dividers
Maintenance-free and reliable operating elements with few parts inside the enclosure
Easiest operation
Pressure-resistant enclosure with defined pressure relief
Implementation of the Development Tasks
Power Transmission and Distribution
© Siemens AG 2006
Page 7 June 07 Medium Voltage Division
Situation with Gas-Insulated Switchgear
Today’s state of the art is gas-insulated switchgear with the following main benefits:
Small, compact dimensions Independent of environmental effects and climate Widely maintenance-free Maximum safety for staff Low fire risk Arc-fault tested
Advantages:
Low invest for buildings due to compact dimensions and climate-independent design
Maximized power supply reliability Maximum personal safety Lowest life cycle costs Reduced operational costs - no additional
maintenance costs
Power Transmission and Distribution
© Siemens AG 2006
Page 8 June 07 Medium Voltage Division
First SIEMENS Gas-Insulated Medium-Voltage Switchgear (April 1982)
Kulmbach / Germany
8DA10
16 panels
24 kV / 16 kA (3s) / 1250 A
Power Transmission and Distribution
© Siemens AG 2006
Page 9 June 07 Medium Voltage Division
Applications Today
Tibet / China
8DA10
205 panels
40.5 kV / 31.5 kA (3s) / 1250 A
Site altitude: 3000 – 5000 m
Power Transmission and Distribution
© Siemens AG 2006
Page 10 June 07 Medium Voltage Division
First SIEMENS Gas-Insulated Medium-Voltage Ring-Main Unit (April 1982)
Stadtwerke Lambrecht / Pfalz, Germany
Project: Municipal power supply
Electrical data: 24 kV, 16 kA, 630 A
Typicals: 8DJ10, scheme 10
Power Transmission and Distribution
© Siemens AG 2006
Page 11 June 07 Medium Voltage Division
Switchgear Type 8DJTypical Application Examples
25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens
Thank you very much for your attention!