In, a protective relay is a device designed to trip a when a is detected. The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current,, reverse flow, over-frequency, and under-frequency.
In, a single-mode optical fiber, also known as fundamental- or mono-mode, is an designed to carry only a single of light - the. Modes are the possible solutions of the for waves, which is obtained by combining and the boundary conditions. These modes define the way the wave travels through space, i.e. how the wave is distributed in space. Waves can have the same mode but have different frequencies. This is the case i.