| (19) |
 |
|
(11) |
EP 0 388 133 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
31.07.1991 Bulletin 1991/31 |
| (43) |
Date of publication A2: |
|
19.09.1990 Bulletin 1990/38 |
| (22) |
Date of filing: 13.03.1990 |
|
|
| (84) |
Designated Contracting States: |
|
FR GB IT |
| (30) |
Priority: |
17.03.1989 JP 66864/89
|
| (71) |
Applicant: NGK INSULATORS, LTD. |
|
Nagoya City
Aichi Pref. (JP) |
|
| (72) |
Inventors: |
|
- Imakoma, Takashi
Aichi-gun, Aichi-ken 470-01 (JP)
- Kondo, Seiichi
Moriyama-ku, Nagoya-shi, Aichi-ken 463 (JP)
- Kasaki, Fumio
Tajimi-shi, Gifu-ken 507 (JP)
|
| (74) |
Representative: Paget, Hugh Charles Edward et al |
|
MEWBURN ELLIS
York House
23 Kingsway
London WC2B 6HP
London WC2B 6HP (GB) |
|
| |
|
| (54) |
Suspension insulator |
(57) Disclosed is a suspension insulator having a shed (2) with several ribs (4) formed
concentrically and integrally on the lower face and a head (3) integrally formed at
the central portion on the upper face of the shed(2), with a metal cap (5) being fixed
on the head (3) and a metal pin (7) being fixed in the cavity of the head (3). The
insulator is designed to have dimensions in such a way that the following equations
[1] to [3] are satisfied:
0.8 h < ℓ [1]
2.5≦ L/H≦ 4.5 [2]
D≦ L [3],
where, h is the height of the ribs (4); ℓ is the interval between the ribs (4); L
is the creepage distance as measured along the surface of the shed (2), D is the diameter
of the shed (2); and H is the connection pitch of a suspension insulator unit forming
an insulator string.