The coefficient $k$ varies substantially for different voltage levels and consumer classe.
- 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.
- A planning work group at Electrobras called GTCP recommended in 1983 the value 0.20.
- A Brazilian study by a committee called CODI analized 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 puslished 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 $k = (μ - LF^2)/(LF - LF^2)$
|0.04||CODI 1996 (minimum)|
|0.15||LV commercial consumers|
|0.18||LV residential consumers|
|0.2||GTCP Eletrobras 1983|
|0.3||Neher McGrath 1953|
|0.39||LV heavy industrial activities|