Mechatronic Systems Engineering 2201A/B Lecture Notes - Lecture 9: Electric Generator, Alternating Current, Direct Current
25 Dec 2019
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Document Summary
Alternating current (ac): current that varies with time and reverses directions periodically. Fierce industrial competition between dc-based and ac-based electric power transmission/distributions systems claimed ac current as the winner. Ac voltage can be easily changed (increased or decreased) using a transformer. Dc voltage cannot be changed easily (without significant losses of energy), and therefore, the cost of voltage conversion is usually much higher. Easy voltage change implies more efficient transmission and distribution of electric energy, as transmission losses generally decrease with increasing voltage. Ac power is easy to generate with rotating machinery (example: an electric generator) Ac power is easy to use to drive rotating machinery (example: an ac electric motor) Ac power provides a fixed frequency signal (60 hz in north america, 50 hz in europe) that can be used for timing purposes and synchronization. The phase angle is related to time shift between and the reference sinusoid.
