DANSK DSF/FPREN 60071-2 PDF

This part of IEC 60071 constitutes an application guide and deals with the selection of 340 insulation levels of equipment or installations for three-phase electrical systems. Its aim is to 341 give guidance for the determination of the rated withstand voltages for ranges I and II of IEC 342 60071-1 and to justify the association of these rated values with the standardized highest 343 voltages for equipment. 344 This association is for insulation co-ordination purposes only. The requirements for human 345 safety are not covered by this application guide. 346 It covers three-phase systems with nominal voltages above 1 kV. The values derived or 347 proposed herein are generally applicable only to such systems. However, the concepts 348 presented are also valid for two-phase or single-phase systems. 349 It covers phase-to-earth, phase-to-phase and longitudinal insulation. 350 This application guide is not intended to deal with routine tests. These are to be specified by 351 the relevant product committees. 352 The content of this guide strictly follows the flow chart of the insulation co-ordination process 353 presented in figure 1 of IEC 60071-1. Clauses 2 to 5 correspond to the squares in this flow 354 chart and give detailed information on the concepts governing the insulation co-ordination 355 process which leads to the establishment of the required withstand levels. 356 The guide emphasizes the necessity of considering, at the very beginning, all origins, all 357 classes and all types of voltage stresses in service irrespective of the range of highest voltage 358 for equipment. Only at the end of the process, when the selection of the standard withstand 359 voltages takes place, does the principle of covering a particular service voltage stress by a 360 standard withstand voltage apply. Also, at this final step, the guide refers to the correlation 361 made in IEC 60071-1 between the standard insulation levels and the highest voltage for 362 equipment. 363 The annexes contain examples and detailed information which explain or support the 364 concepts described in the main text, and the basic analytical techniques used.