Due to the frequent switch of LP devices, current flowing through LP connection lines changes frequently.
Over current status is determined the coordinator, which compares the rated current to the present current, controls all LP consumer devices statuses and calculates the rated current of every LP connection line. Defining the measured current as IM and the rated current as IR, the over current status of a LP connection line can be divided into 5 zones, as shown in Fig. 7, where k1, k2, k3 are defined as: 0