(19)

(11)

EP 0 429 494 A1

(12)

(43) Date of publication: 05.06.1991 Bulletin 1991/23 (21) Application number: 89909009.0 (22) Date of filing: 13.07.1989

(51) International Patent Classification (IPC):  H02P 3/ 06( . ) (86) International application number: PCT/GB1989/000805 (87) International publication number: WO 1990/000832 (25.01.1990 Gazette 1990/03)

(84) Designated Contracting States: DE GB (30) Priority: 14.07.1988 GB 19880016714 (71) Applicant: The University of Glasgow, University Court Glasgow G12 8QQ, Scotland (GB)	(72) Inventors: BOWER, Peter, Graham Glasgow (GB) MILLER, Timothy, John, Eastham Glasgow G61 1EA (GB) (74) Representative: MacDougall, Donald Carmichael  Cruikshank & Fairweather 19 Royal Exchange Square Glasgow G1 3AE, Scotland Glasgow G1 3AE, Scotland (GB)