Optical devices are optoelectronic components used in optical communication that perform various functions based on the photoelectric conversion effect. Depending on whether photoelectric conversion occurs during operation, optical devices can be divided into active devices and passive. Optoelectronics (or optronics) is the study and application of electronic devices and systems that find, detect and control light, usually considered a sub-field of photonics.
[pdf] The article provides an overview of protective relaying principles and their applications for high-voltage power system components. It covers the protection methods for generators, transformers, buses, and transmission lines using various relay types to detect and. A protective relay is an intelligent electrical device designed to detect faults in power systems and initiate corrective actions such as tripping a circuit breaker. The selection and applications of. The rectangular devices are test connection blocks, used for testing and isolation of instrument transformer circuits. It initiates the operation of circuit breakers to isolate the affected section.
[pdf] 
