ANSI Class

With long stud

57 -1L

57-2L

57-3L

57-4L

With short stud

57-1S

57-2S

57-3S

57-4S

Leakage distance/in mm

14  356

22 559

29  737

1015

Dry arcing distance/in mm

6 1/2  165

9 1/2    241

12 1/4     311

368

Cantilever strength/lb kN

2800  12.5

2800   12.5

2800      12.5

12.5

Fig. No

1

2

3

4

Average flashover voltage

Low-frequency

Dry/kV

80

110

125

150

Wet/kV

60

85

100

125

Critical-impulse

Positive/ kV

130

180

210

255

Negative/ kV

155

205

260

340

Radio-influence voltage date

Test voltage to Ground/ kV

15

22

30

44

Maximum RIV at 1.000kc/μV

100

100

200

200

For ANSI Class

57-1S

57-1L

57-2S 3S 4S

57-2L 3L 4L

Main dimensions steel stand mm

A

1 3/4      44.5

7      178

1 3/4     44.5

7      178

B

1 7/16   36.5

4 1/2   114

1 7/16    36.5

4 1/2   114

C

1 7/32   31.0

1 7/32   31.0

1 7/32   31.0

1 7/32   31.0

D

3/4

3/4

3/4

3/4

E

5/8

5/8

3/4

3/4