Current effective value measuring method, measuring device and circuit breaker

The invention discloses a current effective value measuring method, particularly relates to an effective value measuring method of low-frequency currents output by wind power generation, tidal power generation and the like and belongs to the technical field of electrical measurement. The current effective value measuring method comprises the following steps of performing AD sampling on to-be-measured currents, sequentially storing current AD values obtained by sampling into an first-in first-out queue with the length being n, wherein the sampling period of the AD sampling is one n of a maximum period of the to-be-measured currents and n is an integer which is larger than or equal to 2; calculating the effectively value of the to-be-measured currents according to the current AD values stored in the first-in first-out queue in accordance with a preset period, wherein the preset period is smaller than the maximum period of the to-be-measured currents and larger than the sampling period of the AD sampling. The invention also discloses a current effective value measuring device and a circuit breaker. The current effective value measuring method, the current effective value measuring device and the circuit breaker can rapidly and accurately measure and protect the effective value of the low-frequency currents output by the wind power generation, the tidal power generation and the like in real time.