Calculations according to IEC are made for 0.1, 0.2, 0.3, 0.5, 1, 2, 3 and 5 sec.

Calculations according to ICEA are made for 1, 2, 4, 8, 16, 30, 60 and 100 cycles.

Symbol
$t_{\mathrm{k}}$
Unit
s
Used in
$\epsilon_{\mathrm{k}}$
$\theta_{\mathrm{kf}}$