Study on Failure Frequency of Sensitive Equipment Caused by Voltage Sag

A method calculating the failure frequency of sensitive equipment caused by voltage sag in the monitoring period is proposed. In life and production, destruction of sensitive equipments fault caused by voltage sag is a serious power quality problem. It is a transition process that sensitive equipments fault caused by voltage sag, which is from a safe state to fault state, and it is uncertain whether it is fault in the region of the voltage tolerance curve (VTC), Probability density function is used to characterize failure state caused by voltage sag which happened in the voltage tolerance curve, and using the cumulative method to calculate sensitive equipment fault frequency through the voltage sag characteristic parameters in the period of monitoring time. Using personal computers as experiment equipments, and comparing the outcome with the result calculated by using the ITIC curve, its proved this method is superior and accurate.