Vacuum Technology towards High Voltage:

there seem no principal limits

Cired 2003

Prepaired Contribution to Q1-6

Prof René Smeets - Paul Leufkens: Kema HPL

The challenges for development

• dielectric (single- or multi-gap?):

– breakdown voltage determined by contact surface condition

• late breakdown:

– sometimes unexpected (self-restoring) breakdown

• current interruption:

– arc control by axial magnetic field more difficult at larger gaps

• rated current:

– typical normal current of VCB rather low for HV application

• life-cycle cost:

– lower maintenance costs cancel higher investment

• operational:

– EM drives may enhance reliability and functionality

• environmental:

– SF6 is strong greenhouse gas; possible legal restrictions/taxes

• switching:

– VCB excellent at switching steep transient recovery voltages

The benefits

Certifying experience of KEMA

certificates on circuit-breakers (1997-2002) by KEMAcertificates on circuit-breakers (1997-2002) by KEMAcertificates on circuit-breakers (1997-2002) by KEMAcertificates on circuit-breakers (1997-2002) by KEMA

0

20

40

60

80

100

120

4.7

6

7.2

7.5

12

15

15.5

17.5

24

28

36

38

40.5

72.5

123

145

245

300

420

550

rated voltage (kV)

nu

mb

er

of

KE

MA

ce

rtif

ica

tes

19

97

-20

02 vacuum

SF6

95% vacuum 100% SF6

comm.available (Japan)

recently tested at KEMA