arc resistance
TRANSCRIPT
25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens
Resistance to Internal Faults
Martin SchaakOlaf BischurThomas Stommel
Power Transmission and Distribution
© Siemens AG 2006
Page 2 June 07 Medium Voltage Division
Topics
Resistance to internal faults
Causes and physical effects
Basic standard IEC 62271-200
Test object NXPLUS C
Live test
Analysis and review
Open questions
Power Transmission and Distribution
© Siemens AG 2006
Page 3 June 07 Medium Voltage Division
Causes of Internal Faults
Ageing of insulating materials under electrical stress
Corrosion
Overstressing
Ferroresonance, overvoltages
Defective installation, incorrect maintenance
Maloperation
Pollution, humidity, small animals penetrating in the switchgear
Power Transmission and Distribution
© Siemens AG 2006
Page 4 June 07 Medium Voltage Division
Electrical Accidents
1 internal arcing fault per 10,000 GIS panels and year
Reported electrical accidents in the sphere of activity of BGFE
49.3%
Electric shock
27.0%
20.8%
5.8%1.5%
27.4%
47.1%
Arcing fault Electric shock and arcing fault
Arcing fault with electro-ophthalmia and
burns
67.5 %
80 %
0 %
20 %
40 %
60 %
Electrical effects of high voltage
Institute for the research of electrical accidents
1996-2000
2001-2005
Power Transmission and Distribution
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Physical Effects of an Internal Fault
Temperature riseand pressure rise
Radiation
EvaporationThermal conduction, melting
Electric arc, plasma beam with a
temperature of about 20,000 °C
Energy balance
Power Transmission and Distribution
© Siemens AG 2006
Page 6 June 07 Medium Voltage Division
Possible Effects of an Internal Fault
Light effect (blinding, shock)
Noise development (hearing damage)
Thermal load (heat, burns)
Smoke development (breathing)
Projection of parts (cuts)
Toxic effects (intoxication)
Pressure development (damage to buildings / walls and door), physiological influence on a person (shock, falling caused by defensive reaction, circulatory insufficiency)
Power Transmission and Distribution
© Siemens AG 2006
Page 7 June 07 Medium Voltage Division
Avoidance of Internal Faults
Quality during design, production and installation
Training of personnel (avoidance of maloperation)
Maintenance (replacement of worn-out parts, cleaning)
Active systems for fault detection
Other measures for avoidance of internal arcs are described in IEC 62271-200, Table 2: “Locations, causes and examples of measures to reduce the probability of internal faults”
Power Transmission and Distribution
© Siemens AG 2006
Page 8 June 07 Medium Voltage Division
Comparison of the Internal Arcing Test IEC 60298 vs. IEC 62271-200
Test conditions according to IEC 60298 Test conditions according to IEC 62271-200
Application of test conditions by agreement between manufacturer and operator
Test according to defined conditions of the standard
Any room height, distances Defined test setup, distances
Any points for arc initiation Defined points for arc initiation
Defined acceptance criteria can be applied Defined acceptance criteria must be applied
Feeding directions freely selectable Defined feeding direction
Declaration on rating plate not necessaryInternal arc classification (IAC) must be declared on the rating plate
Description of test results Test passed / not passed
Power Transmission and Distribution
© Siemens AG 2006
Page 10 June 07 Medium Voltage Division
Designation of the Internal Arc Classification
* F = Front; L = Lateral; R = Rear
Classification: IAC ( “Internal Arc Classified” )
Accessibility: A (F, L, R)*B (F, L, R)*C
Test values: Current [ kA ] and duration [ s ]
Example 1: IAC A FLR 25 kA 1 s
Example 2: IAC B FL 25 kA 1 s
Power Transmission and Distribution
© Siemens AG 2006
Page 11 June 07 Medium Voltage Division
Test Procedure
Busbar compartment
Circuit-breaker compartment
Cable compartment
For switchgears with internal arc classification (IAC) according to IEC 62271‑200:
Test object consists of 2 panels as a minimum Test in every compartment and at least in the
end panel Completely equipped test specimen
(reproductions are accepted) Test only on not pre-stressed functional
compartments Defined distances (walls, ceiling) 40 % to 50 % of the surface must be covered
with indicators Defined direction of power flow and points of
arc initiation
SF6-insulation may be replaced by air
Evaluation of all five criteria
Power Transmission and Distribution
© Siemens AG 2006
Page 12 June 07 Medium Voltage Division
Test Arrangement Conditions (1)
(a) Height of ceiling - Height of test object + 600 mm ± 100 mm- If height of test object ≤ 1.5 m > Min. height of ceiling 2 m
(b) Rear wall- Non-accessible 100 mm ± 30 mm- Accessible 800 mm + 100 mm
(c) Indicators- Covering 40 to 50 % (checker pattern)
800 mm100 mm
600 mm
Power Transmission and Distribution
© Siemens AG 2006
Page 13 June 07 Medium Voltage Division
Test Arrangement Conditions (2)
For the test object in the room mock-up
5000 mm
2250
mm
600 mm
Three phase infeed via
cable
Three phase arc ignition in circuit-
breaker compartment
100 mm
600 mm
2750
mm
300
mm
5000 mm
D
50
00
mm
A
Indicators
Indicators
InfeedTest
object
F
Ind
ica
tors
E
C
C
B
F
C
A : 1200 mm
Height of indicators = 2000 mm
B : 1225 mm
C : 500 mm
D : 100 mm
E : 800 mm
F : 300 mm
For the indicators
Power Transmission and Distribution
© Siemens AG 2006
Page 14 June 07 Medium Voltage Division
Acceptance criteria
Criteria according to IEC 62271-200
No. 1
Correctly secured doors an covers do not open
Deformations are accepted with restrictions Additionally, if distance to wall after installation is smaller than tested: The permanent deformation is less than the intended distance to the wall
No. 2No fragmentation of the enclosure
No projection of parts above 60 g
No. 3 Arcing does not cause holes in the accessible sides up to a height of 2 m
No. 4 Indicators do not ignite due to the effect of hot gases
No. 5 The enclosure remains connected to its earthing point
new
new
Power Transmission and Distribution
© Siemens AG 2006
Page 15 June 07 Medium Voltage Division
Test Setup
Current test object, open vessel and ignition wire
Power Transmission and Distribution
© Siemens AG 2006
Page 16 June 07 Medium Voltage Division
Test Parameters
Type of accessibility “A”
Free-standing arrangement
Short-circuit current: 25 kA
Short-circuit duration: 1 s
Height of ceiling: 2.8 m
Switch position of all devices: “CLOSED”
Operating tool inserted
Infeed via right-hand disconnector panel
3-phase arc initiation in gas vessel of CB-panel at cable connection bushings
Direction of power flow as feeder panel
IAC A FLR 25 kA 1 s
Power Transmission and Distribution
© Siemens AG 2006
Page 18 June 07 Medium Voltage Division
Test Preparations
Arrangement of test object in room mock-up
Power Transmission and Distribution
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Page 19 June 07 Medium Voltage Division
Live Test
Performance of internal arcing test
(Changeover to high-power testing laboratory)
Power Transmission and Distribution
© Siemens AG 2006
Page 20 June 07 Medium Voltage Division
Flashback (Slow Motion of Live Test)
Test recorded from different camera positions
Camera A
Camera BCamera C
Switchgear front
Switchgear side
Power Transmission and Distribution
© Siemens AG 2006
Page 21 June 07 Medium Voltage Division
Acceptance Criteria
Criteria according to IEC 62271-200
No. 1 Correctly secured doors and covers did not open.
No. 2No fragmentation of the enclosure occurred and no parts with an individual mass > 60 g were projected.
No. 3 Arcing did not cause holes in the accessible sides of the enclosure up to a height of 2 m.
No. 4 No indicators ignited due to the effect of hot gases.
No. 5 The enclosure remained connected to its earthing point.
Power Transmission and Distribution
© Siemens AG 2006
Page 22 June 07 Medium Voltage Division
Resulting Document
As an example from previous tests