Transient load period

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.

Symbol

$\tau$

Unit

Formulas

$\operatorname{expi}\left(\frac{-{L_{cm}}^2}{4\tau \delta_{soil}}\right)$

Related

$\delta_{soil}$

Thermal diffusivity soil [m$^2$/s]

$L_{cm}$

Depth of laying [m]

Used in

$\alpha_t$