Insulation level

NXB and NXBD

NXA

Rated voltage

kV

12

24

36

Power frequency withstand voltage, 50 Hz

– to earth and between phases

kV

28

50

70

– across the isolating distance

kV

32

60

80

Lightning impulse withstand voltage

– to earth and between phases

kV

75

125

170

– across the isolating distance

kV

85

145

195

Current ratings

Rated normal current

A

630

630

630

Mainly active load breaking current

A

630

630

630/400

Number of breaking operations CO

n

400

400

100/400

Line-charging breaking current

A

50

50

2

Cable-charging breaking current

A

50

50

40

Earth fault breaking current

A

50

50

130

Cable charging breaking current

under earth fault conditions

A

28

28

80

No-load transformer breaking current

A

20

Short-circuit ratings

Short-time withstand current, Ik

kA/s

20 kA/4 s

20 kA/4 s

12.5 kA/3 s

Peak withstand current

kA

50

50

31.5

Short-circuit making current

kA

50

50

31.5

Number of making operations

– main switch 50 kA (CL E3)

n

5

5

– main switch 31.5 kA (CL E3)

n

10

10

5

– earthing switch 50 kA (CL E2)

n

3

3

– earthing switch 31.5 kA (CL E3)

n

5

5

Creepage distance

mm

620

620

1440

Ambient air temperature limits

-40°C…+60°C*1

-40°C…+60°C*1

-40°C…+60°C

Mechanical endurance (number of close-open operations)

– main switch

n

5000

5000

5000

– earthing switch*2

n

2000

2000

Filling pressure (+20°C)

bar (abs)

1.4-1.5

1.4-1.5

1.8-1.9

Alarm pressure (+20°C)

– density switch

bar (abs)

1.2

1.2

1.65

– density gauge

bar (abs)

1.2

1.2

1.6

– low gas lock-out mechanism

bar (abs)

1.1

1.1

1.6

Weight

NXB (manual operated type)

kg

82

NXA (manual operated type)

kg

117

NXBD (manual operated type)

kg

138

Degree of protection of the mechanism box

IP67

IP67

IP67