eferences The best termination for a multi-way connector is to use a screened conductive backshell for the connector and to clamp the cable shield EEC (1989) Council Directive of 3rd May 1989 on the approxima- firmly to it. The backshell must make contact directly with the tion of the laws of the Member States relating to Electromag- conductive shell of the connector itself, and this in turn must make netic Compatibility (89/336/EEC), Official Journal of the good 360° contact with the shell on its mating connector, which European Communities, No L 139, 23rd May. must be bolted firmly and conductively to the equipment case. Any Goedbloed, J.J. (1987) Transients in Low-Voltage Supply Net- departure from this practice, in terms of not bolting directly to the works, IEEE Transactions on Electromagnetic Compatibility, case, not having mating conductive shells on the connectors, and not EMC-29, (2), May, pp. 104-115. Screened enclosures Cable shield connected to enclosures at both ends Figure 23.35 R.F. cable shield connections References 23/27 Pigtail Backshell grounded via connector shell Conductive clamp over cable shield Figure 23.36 Cable screen terminations: (a) no connection (bad); (b) pigtail connection (poor); (c) screened backshell (good) Goedbloed, J.J. and Pasmooij, W.A. (1990) Characterization of Ott, H.W. (1985) Controlling EMI by Proper Printed Wiring Board Transient and CW Disturbances induced in Telephone Sub- Layout 6th Symposium on EMC, Zurich, March 5-7. scriber Lines IEE 7th International Conference on EMC, York Paul, C.R. (1980) Effect of Pigtails on Crosstalk to Braided-Shield 28-31st Aug, pp. 211-218. Cables, IEEE Transactions on Electromagnetic Compatibility, Ott, H.W. (1979) Ground - A Path for Current Flow, International EMC- 22, (3), August. Symposium on EMC, IEEE, San Diego, October 9-11. This page intentionally left blank Telecommunication power systems Clive R Nightingale Dip.EE CEng FIEE Formerly Chief Power and Building Services Engineer (BT) Contents Introduction 24/3 A.C. Systems 24/3