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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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The Rotor frequency (𝑓𝑟) at standstill and running condition is ___________ and __________ respectivelly.
𝒇𝒓=𝒇 and 𝒇𝒓=𝒔𝒇
𝒇𝒓=𝒔𝒇 and 𝒇𝒓=𝒇
𝒇𝒓 =𝒇(𝟏−𝑺) and 𝒇𝒓 =𝒇(𝟏−𝑺^2)
𝒇𝒓=𝒇 and 𝒇𝒓=𝒔^2𝒇
𝒇𝒓=𝒇 and 𝒇𝒓=𝒔𝒇
The rotor frequency (𝑓𝑟) at standstill equals the supply frequency (𝑓), and when running, it is given by the slip factor multiplied by the supply frequency (𝑓𝑟 = 𝑠𝑓). This indicates that rotor frequency differs based on the motor's operational state.
The rotor frequency (𝑓𝑟) at standstill equals the supply frequency (𝑓), and when running, it is given by the slip factor multiplied by the supply frequency (𝑓𝑟 = 𝑠𝑓). This indicates that rotor frequency differs based on the motor's operational state.
fr=f — Rotor frequency at standstill
fr=sf — Rotor frequency when running
At standstill, the rotor does not rotate and thus has a frequency equal to the supply frequency. Once the rotor starts moving, the slip (𝑠) emerges, which reduces the rotor frequency to a fraction of the supply frequency, leading to 𝑓𝑟 = 𝑠𝑓, where slip is defined as the difference between synchronous speed and actual rotor speed relative to synchronous speed.
The slip factor (𝑠) is a measure of how much slower the rotor turns compared to the synchronous speed.
Induction motors operate with a rotor frequency that changes based on its state, affecting the overall efficiency.
Provides precise rotor operation metrics
Helps in understanding motor performance under different conditions
Requires accurate measurement of supply frequency
Slip can vary with load, complicating frequency calculations
Used in industrial motors for speed control
Essential for designing efficient motor systems
Rotor frequency is crucial for determining motor performance characteristics.
Option B is incorrect because it reverses the relationship of supply frequency to rotor frequency in running condition.
A is correct — the rotor frequency at standstill is equal to the supply frequency, and when running, it is equal to the slip factor times the supply frequency.
Understanding the concept of slip and rotor frequency is essential not only for electrical engineering but also for control systems and motor design.