Section 5(a) in Andhra Pradesh Electricity Regulatory Commission (Transmission Standards of Performance) Regulation, 2007
(a)Voltage Variation:(i)Voltage Variation is defined as the deviation of the root-mean-square (RMS) value of the voltage from its nominal RMS value, expressed in terms of percentage. Voltage Variation may be either of short duration not exceeding one minute or of long duration for a time greater than one minute.(ii)For the purpose of these standards, the sustained variation in steady state voltage exceeding one minute duration shall be considered. The specified permissible limits of sustained voltage variation shall not apply in the cases where the circumstances are reasonably beyond the control of State Transmission Utility/Transmission Licensee e.g. major break-down, grid failures, accidents, system distress conditions, etc.(iii)State Transmission Utility/ Transmission Licensee shall make all possible efforts to ensure that the grid voltages remain within the following voltage levels at all points of its Transmission System:
