IEEE 690-2018 pdf free.IEEE Standard for Design and Installation of Cable Systems for Class 1E Circuits in Nuclear Power Generating Stations.
a) Cables. ficid splices, and connections shall have a qualified life for all service conditions that are postulated tbr the areas where they are to be used and shall be qualified in accordance with the applicable parts of IEC/JEEE 60780-323. IEEE SW 383. and IEEE Std 572.
b) All cables (including fiber optic cables) shall pass the vertical tray flame test described in IEEE SW I 2021M [1417]. or NFPA 262. except that switchboard wires, coaxial, twin axial and triaxial cables shall, as a minimum, pass the UL VW- I flame test (UL 1581). In addition, all low-voltage conductors going into a multiconductor cable shall pass the UL VW-l flame test.
c) For analog control syslems. the requirements may be different from newer digital control systems. Cables and shielding for digital systems, whether for control or instrumentation, should be treated the same.
5. Conductor sizing
This clause establishes cable conductor sizing requirements for various types of cable installations for Class iF circuits. Power cables shall be sized in accordance with National Electrical Code’ (NEC’) (NFPA 70’), IEEE Std 835, or NEMA WC 51/ICEA P-54-440. The ampacity tables provided in thcsc documents arc vciy specific to the cable installation method. It is important to understand the bases for the ampacities provided in their tables so that the appropriate selection is made based on the cable installation (e.g.. random till, non- spaced versus single-layer for open top trays). Additional guidance for cable ampacity determination relating to maintained spacing and conduit grouping factors can be found in IEEE Std S-i 35-I.
Cables shall be sized to carry load current with the following special consideraiions;
a) Unless specific site ambient conditions or the safety analysis of the plant supports other ambient tcmpcratures, the minimum ambient temperatures used in calculating cable ampacitics shall be 40 °C for exposed installations. For buried installations, earth ambient will vary depending on geographical location (typically between 20 C to 30 °C). Ampacity tables in IEEE Std 835 arc based on 25 °C earth ambient. IEEE Std S-135-l provides additional discussion. The ratings for buried cables are significantly affected by the earth thermal resistivity and soil thermal stability, Knowledge of these parameters is important in rating of a buried cable system (IEEE Std 835). (‘onductor size shall be selected to carry required normal, emergency overload, and short-circuit current without exceeding rated temperature of the insulation for the respective condition, and considering appropriate environmental and operational design parameters. Temperature extremes under design basis events shall be addressed by the qualification of the cable in accordance with IEEE Std 383.
b) Cable ampacity shall consider different conditions such as (direct buried, sun exposure, exposed conduit, cable penetration fire stops. covered cable trays, wireways, proximity to hot steam lines. raceway fill. ambient temperature, soil thermal resistivity, conductor temperature, application of (Ire wrap’barricrs.coatings and conduit groupings) and the conductor size shall be selected or dc-rated for the most limiting condition.
c) Selection of conductor size shall also consider voltage regulation requirements, shield circulating currents, and mechanical strength in addition to cable current carrying requirements.IEEE 690 pdf download.