Load loss coefficient

The coefficient $k_{LF}$ varies substantially for different voltage levels and consumer classes.

Previous works such as Neher and McGrath in 1953 suggested the coefficient to be 0.30. This is the value used by other ampacity tools, where the constant coefficient cannot be changed.
G. Anders wrote in his book 'Rating of Electric Power Cables', 1997, chapter 12.2.1 that the value of the coefficient can be taken as equal to 0.3 for transmission circuits and equal to 0.2 for distribution networks.
A planning work group at Electrobras called GTCP recommended in 1983 the value 0.20.
A Brazilian study by a committee called CODI analyzed the global load curves of several distribution companies and found the coefficient to lay within 0.04 and 0.14.
An American/Canadian study by Gustafson and Baylor, published by IEEE in 1998 set the coefficient to 0.08.
A study by Oliveira et al. published by IEEE PES in 2006 found coefficients for different brazilian tariff groups and voltage levels such as LV commercial, residential and industrial consumers as well as MV consumers. For low voltage distribution grids with large amount of industrial activities, the coefficient surpasses the specified range up to 0.03.

The constant coefficient can be estimated from the real load curves using the relationship $k_{LF}=\frac{\mu-LF^2}{LF-LF^2}$.

Symbol

$k_{LF}$

Unit

p.u.

Used in

$LF$

$\mu$

$\mu_{w}$

$\mu_{y}$

Choices

0.04	CODI 1996 (minimum)
0.08	IEEE 1988
0.1	MV consumers
0.15	LV commercial consumers
0.18	LV residential consumers
0.2	GTCP Eletrobras 1983, Anders 1997 for distribution grids
0.3	Neher McGrath 1953, Anders 1997 for transmission circuits
0.39	LV heavy industrial activities