EN 50160:2010 – Voltage characteristics of electricity supplied by public electricity networks

4.2.2 Supply voltage variations
4.2.2.1 Requirements Under normal operating conditions excluding the periods with interruptions, supply voltage variations should not exceed ± 10 % of the nominal voltage U n . In cases of electricity supplies in networks not interconnected with transmission systems or for special remote network users, voltage variations should not exceed + 10 % / – 15 % of U n . Network users should be informed of the conditions.
NOTE 1 The actual power consumption required by individual network users is not fully predictable, in terms of amount and of contemporaneity. As a consequence, networks are generally designed on a probabilistic basis.
If, following a complaint, measurements carried out by the network operator according to 4.2.2.2 indicate that the magnitude of the supply voltage departs beyond the limits given in 4.2.2.2 causing negative consequences for the network user, the network operator should take remedial action in collaboration with the network user(s) depending on a risk assessment. Temporarily, for the time needed to solve the problem, voltage variations should be within the range + 10 % / – 15 % of U n , unless otherwise agreed with the network users.
NOTE 2 In accordance with relevant product and installation standards and application of IEC 60038, network users’ appliances are typically designed to tolerate supply voltages of ± 10 % around the nominal system voltage, which is sufficient to cover an overwhelming majority of supply conditions. Generally, appliances do not need to be designed to handle wider voltage variations.
NOTE 3 Identification of what is a “special remote network user” can vary between countries, taking into account different characteristics of national electric systems as, for instance, limitation of power on the supply terminal and/or power factor limits.
4.2.2.2 Test method Under normal operating conditions: − during each period of one week 95 % of the 10 min mean r.m.s. values of the supply voltage shall be within the range of U n ± 10 %; and − all 10 min mean r.m.s. values of the supply voltage shall be within the range of U n + 10 % / – 15 %.
EN 50160:2010 – Voltage characteristics of electricity supplied by public electricity networks