Dimensioning of the PE with the aid ofcalculation I2txsec. Appendix B (normative)

Technical System Catalogue Ri4Power

Ri4Power Dimensioning of the PE with the aid of Values for factor k for insulated PE conductors not con- calculation I2txsec. Appendix B (normative) in contact with cable coverstained in cables, or for uncoated PE conductors where Procedure for calculating the cross-section of PE Table 16: Factor k depending on the conductor material conductors with regard to thermal stresses from and insulating material short-term currents. Insulation of the PE conductor The cross-section of PE conductors that must withstand or cable cover the thermal stresses of currents for a duration of 0.2 s to 5 s VPE is calculated using the following equation: Thermoplastic EPR Butyl (PVC) rubber Uncoated conductors Final temperature 160 °C 250 °C 220 °C of conductor Sp = I2 t material Factor kConductor√ k Copper 143 176 166 Aluminium 95 116 110 whereby Steel 52 64 60 Sp is the cross-section in mm2 30 °C.The starting temperature of the conductor has been assumed at I is the value of the short-circuit AC current (root- mean-square value) for a malfunction with negligible For further details see IEC 60 364-5-54. impedance that can flow through the short-circuit device, in amperes t is the cut-out time of the disconnecting device in seconds1) k is the factor depending on the material of the PE conductor, the insulation and other parts, as well as on the starting and final temperature; see table opposite 1) The current-limiting effect of the circuit impedances and the current-limiting properties of the protective device (I2t) should be taken into account. 2 - 65 Rittal Technical System Catalogue/Power distribution


Technical System Catalogue Ri4Power
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