Condition monitoring system and storage medium storing thereon condition monitoring program

A condition monitoring system includes a power generator and a condition monitoring apparatus. The condition monitoring apparatus includes, voltage measuring circuit which measures a voltage value of power generated by the power generator, a data memory which stores a past voltage value measured by the voltage measuring circuit, a calculation circuit which calculates a difference between a current voltage value measured by the voltage measuring circuit and at least one past voltage value stored in the data memory, and a controller which determines an issue period indicating a period of time until a trigger signal is issued based on the difference calculated by the calculation circuit, and issues the trigger signal to the condition monitoring apparatus based on the issue period.