POWER DISTRIBUTION, SWITCHGEAR AND CONTROL UNIT COMBINATIONS IN THE TYPE OF PROTECTION PRESSURIZED ENCLOSURE «pxb», «pzc»

 

Pressurized enclosure switchgear combinations are designed for use in gas explosion-hazardous areas of Zones 1 and 2 and meet the requirements of IEC 60079-0 «General Requirements» and IEC 60079-2 «Pressurized Enclosure» or dust for the Zones 21 and 22 of the standard IEC 61241-4 «Protection by pressurization». Along with these standards, an additional test according to IEC 61508-7 «Functional safety of electrical/eletronic/programmable electronic safet-related systems – Part 7: Overview of techniques and measures (SIL 2)» according to Category 3 is required. Safety-related parts according to IEC 61508-7 (SIL 2) Category 3 must be so constructed that

  • One single defect in each of these parts does not lead to the loss of the safety function and,
  • Whenever feasible, the single defect is recognized.