The coefficient $k$ varies substantially for different voltage levels and consumer classe.

The constant coefficient can be estimated from the real load curves using the relationship $k = (μ - LF^2)/(LF - LF^2)$

Symbol
$k_{\mathrm{LF}}$
Unit
p.u.
Used in
$\mu$
$\mu_{\mathrm{w}}$
$\mu_{\mathrm{y}}$
Choices
0.04CODI 1996 (minimum)
0.08IEEE 1988
0.1MV consumers
0.15LV commercial consumers
0.18LV residential consumers
0.2GTCP Eletrobras 1983
0.3Neher McGrath 1953
0.39LV heavy industrial activities