AS NZS 60079.15 pdf download

AS NZS 60079.15 pdf download.Explosive atmospheres Part 15: Equipment protection by type of protection “n” (IEC 60079-15:2017 (ED.5.0) MOD)
1 Scope
This part of IEC 60079 specifies requirements for the construction, testing and marking for Group II electrical equipment with type of protection “n” which includes; sealed devices “nC”, hermetically sealed devices “nC”, non-incendive components “nC” and restricted breathing enclosures “nR” intended for use in explosive gas atmospheres. This part of IEC 60079 applies to electrical equipment where the rated input voltage does not exceed 15 kV r.m.s. AC or DC including where the internal working voltages of the Ex product exceeds 1 5 kV, for example starters for HID luminaires. This part of IEC 60079 supplements and modifies the general requirements of IEC 60079-0, except as indicated in Table 1 . Where a requirement of this part of IEC 60079 conflicts with a requirement of IEC 60079-0, the requirement of this part of IEC 60079 takes precedence.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60079-0 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp 3.1 devices and components “nC” 3.1 .1 hermetically-sealed device “nC” device which is so constructed that it cannot be opened and is sealed effectively by fusion to prevent entry of an external atmosphere 3.1.2 non-incendive component “nC” component having contacts for making or breaking a specified ignition capable circuit but in which the contacting mechanism is designed and constructed so that the component is not capable of causing ignition of the specified explosive gas atmosphere Note 1 to entry: The enclosure of the non-incendive component is not intended to either exclude the explosive gas atmosphere or contain an explosion. This is usually applied to specially constructed switch contacts that are mechanically designed to quench any arc or spark so that they are not a source of ignition. 3.1.3 sealed device “nC” device which is so constructed that it cannot be opened during normal service and is sealed effectively to prevent entry of an external atmosphere 3.2 normally sparking device device with spacings in line with the industrial requirements and which produces arcs and sparks during normal operating conditions Note 1 to entry: Normally sparking devices include switches, relays, and contactors not otherwise Ex protected. 3.3 restricted-breathing enclosure “nR” enclosure that is designed to restrict the entry of gases, vapours and mists 3.4 sealing device device employing a method other than encapsulation to prevent the flow of a gas or a liquid between equipment and a conduit or between separate parts of the equipment by providing sealing facilities
4 General
4.1 Equipment grouping and temperature classification Equipment grouping and temperature classification shall be in accordance with the equipment grouping and temperature classification clauses of IEC 60079-0. 4.2 Potential ignition sources In normal operation and in certain regular expected occurrences specified by this standard, the equipment shall not: a) produce an operational arc or spark unless that arc or spark is prevented from causing ignition of a surrounding explosive atmosphere by one of the methods described in Clauses 7 to 1 0; b) develop a maximum surface temperature in excess of the maximum value appropriate to the temperature class of the equipment, unless the temperature of the surface or hot spot is prevented from causing ignition of a surrounding explosive atmosphere by one of the methods described in Clauses 7 to 1 0 as appropriate, or is otherwise shown to be safe as specified in 5. 4.3 Equipment requirements Equipment or components which in normal operation produce arcs, sparks or hot surfaces which otherwise would be capable of igniting a surrounding atmosphere shall be protected against causing ignition by one or more of the following methods, all of which provide Equipment Protection Level Gc: a) non-incendive component (see Clause 7); b) hermetically sealed device (see Clause 8); c) sealed device (see Clause 9); d) restricted-breathing enclosure (see Clause 1 0).