A Resolver is best described as?

• A. A temperature sensor
• B. A velocity sensor
• C. A type of rotary electrical transformer used for measuring degrees of rotation.
• D. A pressure gauge

Answer: (C)

A resolver is a rotary electrical transformer used to measure degrees of rotation. It consists of a rotating element tied to the shaft and stationary windings; when the resolver is excited with AC, the signals induced in the stator windings are proportional to the rotor angle. Typically, the two stator outputs form sine and cosine components of the angle, so the angular position can be determined (and, with time, the speed can be inferred from how fast that angle changes) after demodulation. This makes resolvers robust and well-suited for harsh environments, unlike sensors that directly measure other quantities. Temperature, velocity, and pressure are measured by separate types of sensors, not by resolvers.