This reports the output frequency this phase is delivering, in units of 0.1Hz, relevant specifically if this power system includes an inverter stage producing AC output, a value that should hold steady at the design frequency, typically 500 for 50.0Hz, regardless of load level if the inverter is functioning correctly. Frequency drift on an inverter's output, unlike voltage sag under load, usually points to a control-loop or oscillator problem in the inverter stage itself rather than simple load-related effects. An admin seeing this phase's output frequency wander away from 500, 50.0Hz, even under light, stable load would suspect an inverter control fault rather than an overload condition.