Two light waves with the orthogonal circular polarization are fed into the multi-turn loop of a special optic fiber; there is a current-carrying conductor inside the loop. If no current is fed to into the loop, the light waves propagate in the fiber loop at equal speeds and come to the loop output simultaneously. If the current is fed to the conductor – the optic fiber appears in the magnetic field of the carried current. During this process, the optical properties of the fiber change, and the speed of the light wave propagation along the loop becomes different; a relative phase displacement occurs between the waves at the loop output. Thus, the measurement of the current by the fiber-optic method comes down to an accurate measurement of the relative phase displacement between the light waves in the sensitive fiber loop placed in the linear magnetic field of electric current.
Advantages of Electronic voltage transformers with capacitive divider
- No copper secondary circuits used which reduces installation and materials costs;
- No high potential and noise (no magnetic field effect) in the secondary circuits due to their natural galvanic insulation (signal transmission via optic fiber);
- The ability to connect an unlimited number of sampled values data users. Easy and flexible system of scaling;
- Low cost of day-to-day operations (ownership) and no risk of electrical power supply interruption for the consumer;
- High-precision measurements and provisions for their integration of all device and receivers of the data;
- The ability to measure the harmonic components in current and voltage up to the 100-th order;
- Our method of measuring (fiber-optic sensors based measuring) will provide the accuracy needed whereas the conventional measurement methods (analog) will always be inaccurate;
- Standardization of network interfacing between the primary and secondary equipment. The ability to implement and standardize all instruments on the basis "standardization instrument solutions" for a wide range of tasks;
- Personnel safety improvements because of inability for lightning or any other forms of electrical current to pass through the optical cables. Thus, preventing power surges or physical danger;
- Alternating and direct current measurement capabilities.