What is the term for the ratio of the highest RMS phase-to-ground power frequency voltage during a fault?

The term for the ratio of the highest RMS phase-to-ground power frequency voltage during a fault is known as the Earth Fault Factor. This concept is crucial in electrical engineering, particularly in the analysis of power systems and substations, as it helps to assess the behavior of the electrical system under fault conditions.

The Earth Fault Factor essentially indicates how much the phase-to-ground voltage exceeds the normal operating voltage during an earth fault scenario. This ratio assists engineers in designing adequate protection systems and ensures that equipment can withstand fault conditions without being damaged.

Understanding the Earth Fault Factor is critical for maintaining the safety and reliability of electrical systems, especially for grounding and protection schemes. In contrast, other terms like Voltage Droop refers to voltage reduction under load, Power Factor deals with the efficiency of power usage, and Fault Impedance refers to the impedance encountered during a fault, none of which directly relate to the ratio of phase-to-ground voltage during a fault condition.