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Technology Past, Present & Future for Medium Voltage Vacuum Switchgear
Kazuhiro Matsuo
2009 Lecture Program of the Joint Electrical Institutions Sydney Engineers Australia, IEEE, IET
10th September, 20092The Joint Electrical Institutions Sydney
●Contents
◆Application and Composition
◆Characteristics of Vacuum
◆Vacuum Interrupter( VI )・VI Configuration・Insulation in Vacuum・Arc Control Technology・Reliability and Quality Control
◆Vacuum Circuit Breaker (VCB)・VCB Configuration・Mechanical Characteristics・Special Application
◆Solid Insulated Switchgear (SIS)・Introduction of Insulation material
◆Toward The Future
●Contents
◆Application and Composition
◆Characteristics of Vacuum
◆Vacuum Interrupter( VI )・VI Configuration・Insulation in Vacuum・Arc Control Technology・Reliability and Quality Control
◆Vacuum Circuit Breaker (VCB)・VCB Configuration・Mechanical Characteristics・Special Application
◆Solid Insulated Switchgear (SIS)・Introduction of Insulation material
◆Toward The Future
10th September, 20093The Joint Electrical Institutions Sydney
Medium Voltage; up to 84kV Vacuum Switchgear Application
Power plant system Power distribution system
Transportation system
Factory system
Buildings systemGeneral supply
system
10th September, 20094The Joint Electrical Institutions Sydney
7.2kVMetal-Clad Switchgear
24kV Spot network system
7.2kVJIS standard power distribution switchgear
Air insulated SWGR
SWGR component
22-77kVCubicle type Gas Insulated Switchgear
Vacuum Circuit Breakers
7.2kV-63kANuclear and thermal power station
3.6-24kV VCB
36kVVCB
36kVFor electric
railway
Thermal relayMulti-function
motor protection relay
Local monitor
Sensor technology
Digital Technology
Computer Technology
66/84kV Compact Cubicle type Gas Insulated Switchgear
36kVSolid Insulated switchgear
Multi-function relay for switchgear
Gas, Solid insulated SWGR
Protection, Control, Monitoring system
Vacuum Interrupters
Medium Voltage Vacuum Switchgear Composition
10th September, 20095The Joint Electrical Institutions Sydney
To extinguish arc – to interrupt current
Ex. flame of a candle….to extinguish flame
・Blast・・
・Extend ・・
・Pour liquid (water..)・・
・Choke off ・・
Candle
10th September, 20096The Joint Electrical Institutions Sydney
Ambient liquid, gas,..Oil
SF6Air
Conductor Conductor
Current flow
Arc
Vacuum
Moving
OCB・・Oil Circuit BreakerACB・・Air Circuit BreakerABB・・Air Blast Circuit BreakerGCB・・Gas Circuit Breaker (SF6)VCB・・Vacuum Circuit Breaker
To extinguish arc – to interrupt current
10th September, 20097The Joint Electrical Institutions Sydney
•Environmentally friendly
SF6 was placed on the list of greenhouse gases under the KyotoProtocol in 1997.
•Low flammability
・High insulation capability
Characteristics in Vacuum
10th September, 20098The Joint Electrical Institutions Sydney
10-2 10-1 1 10 102 103 104 105
30
10
3
1
0.3
Pressure (Pa)
Bre
akdo
wn
Volta
ge (k
V)
Atmospheric Pressure
Characteristics in Vacuum (Paschen’s Curve)
Breakdown Voltage vs. Pressure
Pressure of actual products is 10-5Pa order.
10th September, 20099The Joint Electrical Institutions Sydney
10-2 10-1 1 10 102 103 104 105
30
10
3
1
0.3
Pressure (Pa)
Bre
akdo
wn
Volta
ge (k
V)
Characteristics in Vacuum
103 m3X109 /cm310-5 Pa
10-1 m3X1013/cm310-1 Pa
10-5 m3X1017/cm3103 Pa
Mean free path (N2)Molecular Pressure
10th September, 200910The Joint Electrical Institutions Sydney
0 20 40 60 80 100 120 140 160 180Distance (mm)
175
150
125
100
75
50
25Impu
lse
With
stan
d Vo
ltage
(kV)
VacuumAbs. 0.1MPa SF6
Air
Withstand Voltage Characteristic by Insulation Media
Normal contactStroke in vacuum Air
Insu
latio
n
SF6 Vacuum
13
7
Vacuum Insulation Capability
10th September, 200911The Joint Electrical Institutions Sydney
Arc behavior taken by high-speed camera
Current Interruption in a Vacuum interrupter(The Case of Axial Magnetic Field Electrodes)
Voltage Wave
Current Wave
ContactSeparation
Close Open
ZeroCurrent
→Time
10th September, 200912The Joint Electrical Institutions Sydney
→R
ecov
ery
volta
ge [k
V]
Time after zero current [μs]
極間の過渡回復電圧
Current InterruptionVoltage Wave
Current Wave
ContactSeparation
Zero Current →Time
Transient recovery voltagebetween contacts
→Vo
ltage
→Time
Vacuum
Characteristic of recovery voltage
Characteristics of Recovery Voltage by Insulation Media
Current Interruption
10th September, 200913The Joint Electrical Institutions Sydney
Transition of Circuit Breakers
OCB
ABB
GCB
MBB
VCB
Introduction
DeclineDiffusion
AD
Reference: 遮断器&断路器のメンテナンス入門 オーム社
Transition of production
10th September, 200914The Joint Electrical Institutions Sydney
History of Vacuum Circuit Breakers
Vacuum Switch(7.2kV 100A 50MVA)
1965Vacuum Circuit Breaker(7.2kV 600A 150MVA)
1966
10th September, 200915The Joint Electrical Institutions Sydney
0
5
10
15
20
1975 1980 1985 1990 2000
Year
A/mm2
Glass EnvelopeSpiral + CuTeSe
Ceramic Envelopewith pipe
AMF + CuTeSe
AMFCuCr50
Improvement of AMF & Shield
New Electrode+ CuCr25
Cap
acity
per
uni
t (A
rea
of e
lect
rode
)
Progress on Interrupting Capacity(24kV-25kA Rating)
10th September, 200916The Joint Electrical Institutions Sydney
•High Voltage application
•High Current Interruption
Technical Progress on Vacuum Interrupters
•Compact Design at Same Rating
Insulation in Vacuum
Arc Control
10th September, 200917The Joint Electrical Institutions Sydney
Dielectric Breakdown Mechanism in Vacuum
The field emission is generated from the micro-protrusion on the cathode surface
micro-protrusion
Hypotheses have been proposed;
Field Emission HypothesisField Emission Hypothesis
CATHODE
ANODE
CATHODEANODE
CLUMP
VAPORIZATION↓
BREAKDOWN
Clump is a contamination of micro-particle on the electrode surface.
Clump is accelerated by electrostatic power.
Clump Clump HypothesisHypothesis
10th September, 200918The Joint Electrical Institutions Sydney
Surface roughnessMachining
Electrochemical buffing treatment
◇ Electrochemical buffing treatment+ Machining
Number of voltage application
Bre
akdo
wn
volta
ge [k
V]
Comparison of conditioning effect between machining and electrochemical buffing electrodes
Base material
Melted layer
25μm
Conditioning Effect Conditioning Effect –– what is conditioning effect ?what is conditioning effect ?
Cross-section after conditioning
10th September, 200919The Joint Electrical Institutions Sydney
CauseCause of conditioning effectof conditioning effect
10th September, 200920The Joint Electrical Institutions Sydney
Bre
akdo
wn
field
str
engt
h E b
(kV/
cm)
Effective area Seff (cm2)
Stainless steelCopper
Stainless steelCopper
Sphere-sphereRing-ringVacuum interrupter modelRod(R5)-planeR0d(R5)-planeCylinder-plane
Coaxial cylinder
Stainless steel:
Copper:
Effective area Seff = more than 90% of maximum field strength
Area Effect of Breakdown Field Strength in vacuum
10th September, 200921The Joint Electrical Institutions Sydney
Electrical potential distribution
Electrical field distribution
Example of electrical field analysis of vacuum interrupter
Electrical Field Analysis of Vacuum interrupter
10th September, 200922The Joint Electrical Institutions Sydney
Size Reduction of 72/84kV Vacuum InterrupterSize Reduction of 72/84kV Vacuum Interrupter
Vacuum Circuit Breaker for C-GISThe volume of C-GIS is
reduced to traditional half.
10th September, 200923The Joint Electrical Institutions Sydney
Anode
Arc concentrate in cathode (anode) spot
Control arc not to be concentrated increases capability of interruption
Arcing plasma;Ion and electron
Arcing in Vacuum
Cathode spot (μm in order):Supply plasma by melting cathode electrode
Cathode
Metal vapor emittedcontinuously
Arcing Characteristic in Vacuum
Heating rising
Arc Behavior
Re-ignition
10th September, 200924The Joint Electrical Institutions Sydney
Axial Magnetic Field Method
Spiral
Arc Contact
Coil
CurrentMagnetic Field
ARC
Contrate
Arc
Major Electrodes in the world
Magnetic Driven Method
Contact
Coil
10th September, 200925The Joint Electrical Institutions Sydney
Arc
Magnetic Driven Method
Spiral
Current Flow in Coil
Force against Arc
Typical Configuration
A A
A - ASide section
10th September, 200926The Joint Electrical Institutions Sydney
Generate Axial Magnetic Field by current in coil(Parallel flux to arc)
Axial Magnetic Field Method
Contact
Coil
Current
Typical Configuration
Current Flow in Coil
Magnetic Field
Magnetic Field
10th September, 200927The Joint Electrical Institutions Sydney
Cathode
Anode
•Electrons and Ions are trapped by magnetic line
•Arc is captured within spaces between contacts
•Arc root spread uniformly
Axial Magnetic Field Electrode
Magnetic Field
Spread Uniformly Arc
10th September, 200928The Joint Electrical Institutions Sydney
Magnetic Field Analysis(ELKTRA)
Eddy Current Consideration in 3D
Example of Analyzed Results
Electrode Designing
13.8kV-100kA Type VGB2 VCB
- Largest Vacuum Interrupting Capability in the World -
Large Current interruption
VCB Front ViewVacuum Interrupters
10th September, 200930The Joint Electrical Institutions Sydney
Reliability of Vacuum Interrupters
•Quality Control on Vacuum leakage
•Measurements of Vacuum pressure
10th September, 200931The Joint Electrical Institutions Sydney
Quality Control for Vacuum Life
Inte
rnal
Pre
ssur
e
Internal Pressure Change
Measurement of Internal Pressure
Target life
Critical PressureTolerance
ExpectedVacuum Life
A: Pressure Change caused by Gas Evolution B: Pressure Change caused by leakage
PASS
DEFECT
A
B
C=A+B
Shortage time
10th September, 200932The Joint Electrical Institutions Sydney
Measurement of Vacuum
Source for Magnetic Field
High Voltage DC
Micrometer
Arc Shield
ElectrodeMovement of Electron
Direction of Electrical Field
Magnetic Field from Outside
Principle
Apply Magnetic Fieldand Electrical Field
Increase Path of Electron
Dissociation by Electron
in Collision with Particle
Proportional Current to
Particle (Vacuum pressure)
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