IEEE 690-2018 pdf download

IEEE 690-2018 pdf download.IEEE Standard for Design and Installation of Cable Systems for Class 1E Circuitsin Nucl ear Power Generating Stations.
a) Cables, field splices, and connections shall have a qualified life for all service conditions that are postulated for the areas where they are to be used and shall be qualified in accordance with the applicable parts of IEC/1EEE 60780-323, IEEE Std 383, and IEEE Std 572.
b) All cables (including fiber optic cables) shall pass the vertical tray flame test described in IEEE Std I 202Th1 [B 17], or NFPA 262, except that switchboard wires, coaxial, twin axial and triaxial cables shall, as a minimum, pass the UL VW- 1 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 systems, the requirements may be different from newer digital control systems. Cables and shielding for digital systems. whether for control or instrumentation, should he treated the same.
5. Conductor sizing
This clause establishes cable conductor sizing requirements for various types of cable installations for Class 1 E circuits. Power cables shall be sized in accordance with National Electrical CodeR (NEC) (NFPA 70R), IEEE Std 835, or NEMA WC 5 IiICEA P-54-440. The ampacity tables provided in these documents are very 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 fill, 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- 135-1.
Cables shall be sized to carry load current with the following special considerations:
a) Unless specific site ambient conditions or the safety analysis of the plant supports other ambient temperatures, the minimum ambient temperatures used in calculating cable ampacities shall be 40 °C for exposed installations. For buried installations, earth ambient will vary depending on geographical location (typically between 20 °C to 30 CC). Ampacity tables in IEEE Std 835 are based on 25 °C earth ambient. IEEE Std S-l35-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). Conductor 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 fire wrap/barriers/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.
6. Electrical segregation
6.1 General
This clause establishes requirements for the electrical segregation of cable systems for Class 1 E circuits according to voltage levels, signal levels, and vulnerability to electrical noise pickup. Cables installed in stacked cable trays should be arranged by descending voltage levels with the higher voltage at the top.
6.2 Requirements
The following are requirements for the electrical segregation of cable systems for Class 1 E circuits:
a) Medium-voltage power cables shall he designed and installed to minimize the potential EMF effects on any lower voltage cable system through a failure of medium-voltage power cable system insulation or shielding.
b) Medium-voltage power cable systems shall be designed and installed to minimize electric and magnetic field effects on any lower voltage systems and to minimize mutual inductive coupling.
c) Instrumentation cables shall be shielded and installed to reduce noise pickup from adjacent circuits and equipment.