To provide a voltage regulator that records electric amount around the occurrence of an abnormality of a generator.

The voltage regulator includes: a voltage detector 7 that outputs an output voltage of the generator; a voltage command generator 8 that controls the output voltage of the generator; a subtracter 9 that subtracts the voltage detection signal from the voltage command signal; an operation amplifier 10 that outputs a field control signal by an error signal; a field adjuster 11 that outputs voltage/current of a field power source 3 based on the field control signal; a timer means 21; a memory controller 22 that accumulates electric amount of the output voltage, frequency, a detected current value, field control signal and the like at each time by the timer means 21 and outputs the accumulated data during a prescribed time around the occurrence of a trip signal based on the trip signal at an abnormal time of the output voltage, frequency, a current or the like; a memory 23 for the accumulated data; and an output device that outputs the data of the memory 23. The regulator displays data including time for a prescribed period of time over before and after the occurrence of an abnormality, the output voltage, the frequency, the detected current value, and the field control signal.

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