What does the term 'over frequency' refer to in power systems?

The term 'over frequency' in power systems specifically refers to a condition where the frequency of the electrical power supply exceeds the normal operating frequency, which is typically around 60 Hz in North America or 50 Hz in many other regions. When the frequency increases above this normal range, it indicates that there is an excess of power being generated relative to the demand.

This situation can arise when there is a sudden reduction in load while generation remains unchanged, causing the system frequency to rise. Maintaining frequency within specified limits is critical for the stability and reliability of the power grid. An 'over frequency' condition can potentially lead to equipment damage, cause protective relays to trip, or necessitate the disconnection of generators from the grid to restore balance.

Understanding this concept is crucial for power engineering professionals, as it helps in managing and maintaining the stability of electric power systems effectively.