The transient period $\tau$ is the number of hours of the loading cycle, usually 24 hours.

With a period of 1 year, a soil diffusivity equivalent to the general and a load factor approaching unity, the current rating approaches steady-state load as defined by IEC. A longer transient period would reach a current rating below the steady-state value. Because we allow to select the soil diffusivity for each system separately, this may cause problematic effects for long transient periods. Therefore we limit the transient period to 1 year for buried cables.

$\tau$

s

$\beta_{\mathrm{6}}$

$\beta_{\mathrm{t}}$

$D_{\mathrm{x}}$

$\Delta \theta_{\mathrm{c_{\mathrm{t}}}}$

$\Delta \theta_{\mathrm{d_{\mathrm{t}}}}$

$\Delta \theta_{\mathrm{e_{\mathrm{t}}}}$

$\Delta \theta_{\mathrm{kp}}$

$\gamma_{\mathrm{t}}$

$K_{\mathrm{x}}$

$q_{\mathrm{x}}$

seconds | of the transient period |
---|---|

600 | 10 minutes |

3600 | 1 hour |

7200 | 2 hours |

21600 | 6 hours |

36000 | 10 hours |

43200 | 12 hours |

50400 | 14 hours |

86400 | 24 hours |

129600 | 36 hours |

31557600 | 1 year = 365.25 days |