Note 1 to entry: The transfer function of an ideal PI element is given by

${\displaystyle \frac{V\left(s\right)}{U\left(s\right)}=K_{\text{Ρ}}\cdot \left(1+\frac{1}{T_{\text{i}}\cdot s}\right)}$

where

Ti	is the reset time;
KP	is the proportional action coefficient;
s	is the complex variable of the Laplace transform;
U(s)	is the input transform;
V(s)	is the output transform.

Note 2 to entry: This entry was numbered 351-28-22 in IEC 60050-351:2006.