Hybrid magnetic-optical sensor
This type of transformer is mostly used in applications such as series capacitive compensation of long transmission lines, where a non-grounded of long transmission lines, where a non-grounded measurement of current is required. In this case, several current sensors are required on each phase in order to achieve capacitor surge protection and balance. The preferred solution is to use small toroidally wound magnetic core transformers connected to fibre optic isolating systems. These sensors are usually active sensors in the sense that the isolated systems require a power supply. This is illustrated in figure 6.26.