25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens Medium-Voltage Switchgear - Then and...

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

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


© Siemens AG 2006


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)


© Siemens AG 2006


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


© Siemens AG 2006


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


© Siemens AG 2006


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


© Siemens AG 2006


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


© Siemens AG 2006


First SIEMENS Gas-Insulated Medium-Voltage Switchgear (April 1982)

Kulmbach / Germany

8DA10

16 panels

24 kV / 16 kA (3s) / 1250 A


© Siemens AG 2006


Applications Today

Tibet / China

8DA10

205 panels

40.5 kV / 31.5 kA (3s) / 1250 A

Site altitude: 3000 – 5000 m


© Siemens AG 2006


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

25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens

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25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens Medium-Voltage Switchgear - Then and...

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