OUTPUT CONTROL FOR POWER UNIT

PROBLEM TO BE SOLVED: To shorten a required processing time by simplifying the ON/OFF process of the power source output from the power unit. SOLUTION: When an alarm signal is an ON signal indicating abnormality, the ON/OFF process of the power source output is freely performed according to the decision criterion set so that it is formal when the ON signal is transient or abnormal when the signal occurs frequently. In this case, a counter is provided with the unit which obtains a current counter value by adding/subtracting with time an addition unit value added when the alarm signal is the ON signal and a subtraction unit value which is substracted when it is an OFF signal and set smaller than the addition unit value. The criterion is determined by comparing the current counter value with a previously set permissible limit value and deciding as the normal state including transience when the current counter value is less than the permissible limit value or as the abnormal state based upon the frequency, and on the basis of the criterion, the power source output is turned on and off.