25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens Resistance to Internal Faults Martin...

25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens

Resistance to Internal Faults

Martin SchaakOlaf BischurThomas Stommel

Power Transmission and Distribution

© Siemens AG 2006

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


© Siemens AG 2006


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


© Siemens AG 2006


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


© Siemens AG 2006


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


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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)


© Siemens AG 2006


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”


© Siemens AG 2006


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


© 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


© Siemens AG 2006


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


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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


© Siemens AG 2006


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


© Siemens AG 2006


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


© Siemens AG 2006


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


© Siemens AG 2006


Flashback (Slow Motion of Live Test)

Test recorded from different camera positions

Camera A

Camera BCamera C

Switchgear front

Switchgear side


© Siemens AG 2006


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.

25 Years Gas-Insulated Medium-Voltage Switchgear from Siemens Resistance to Internal Faults Martin...

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