(19)

(11)

EP 0 939 992 A2

(12)

(43) Date of publication: 08.09.1999 Bulletin 1999/36 (21) Application number: 98941442.0 (22) Date of filing: 26.08.1998

(51) International Patent Classification (IPC):  H02H 9/ 08( . ) (86) International application number: PCT/FI1998/000665 (87) International publication number: WO 1999/010959 (04.03.1999 Gazette 1999/09)

(84) Designated Contracting States: AT DE FR SE (30) Priority: 27.08.1997 FI 19970003526 (71) Applicant: ABB Substation Automation Oy 65320 Vaasa (FI)	(72) Inventor: KUISTI, Harri FIN-65350 Vaasa (FI) (74) Representative: Peltonen, Antti Sakari, et al  Oy Kolster Ab, Iso Roobertinkatu 23, P.O. Box 148 00121 Helsinki 00121 Helsinki (FI)