Measurement of the mains frequency
The grid frequency in the synchronous grid of Continental Europe has a nominal value of 50.0 Hz. If the deviation from the nominal value exceeds ±20 mHz, then the primary control is activated. The 20 mHz derived from the sum of the allowable measurement error of 10 mHz and a dead zone of the control characteristic of ±10 mHz.
From ±20 mHz to ±200 mHz the primary control is activated proportional from 0 % to 100 %. Long-term maximum deviations of ±180 mHz are allowed, for short periodes even ±200 mHz are ok. The allowed mains frequency range in normal operation is thus obtained at 49.800 Hz to 50.200 Hz. (ENTSO-E Operation Handbook Load-Frequency Control and Performance)
In case of the breakdown of generation capacity or large consumers, short term deviations until 800 mHz are allowed (49.200 Hz to 50.800 Hz). With higher deviations a massive grid failure is very likely. Then the first step is dropping some consumers or producers, if even this fails, then the network ceased operations (blackout) and the network built up afterwards.
The expression "utility frequency", "grid frequency", "mains frequency", "power frequency" and "line frequency" are synonyms for the frequency of the electric generators, which can be measured in electric supply networks. It is 50 Hz in Europe, USSR, India, China, Australia and Africa, and 60 Hz in USA and the northern parts of south america.
The mains frequency is in all countries, which are directly connected to the synchronous grid, the same (exept short-term fluctuations). These are Belgium, Bosnia-Herzegovina, Bulgaria, Denmark, Germany, Estonia, France, Greece, Italy, Croatia, Latvia, Lithuania, Luxembourg, Macedonia, Montenegro, Netherlands, Austria, Poland, Portugal, Romania, Switzerland, Serbia, Slovakia, Slovenia, Spain, Czech Republic and Hungary. Algeria, Morocco, Tunisia, Western Sahara and Turkey are synchronous with the European grid, too. The other members of ENTSO-E are connected via High-voltage direct current (HVDC) power lines to the synchronous grid and have therefore independent frequencies.
Utility frequency: ? Hz
Phase angle to 50.0 Hz: ? °
Date and time (UTC): ?