The target frequency in the grid is synchronised at 50 hertz (Hz) throughout Europe. To ensure that the frequency always remains stable, the balance between production and consumption of electrical power must always be right. The frequency fluctuates depending on the actual grid load. If the consumption of electrical power is lower than production, the frequency is higher. If consumption is higher than production, the frequency is lower.
The grid time deviation shows the deviation of the grid time from Coordinated Universal Time (UTC), which is caused by frequency fluctuations. One second of UTC time normally corresponds to exactly 50 oscillations of the alternating current. If the frequency is lower than 50 Hz, the fifty oscillations last slightly longer. If it is higher, the fifty oscillations do not last as long.