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GATE 2023 EE – Question 15

Electrical Machines · Three-phase induction machines: principle of operation, types, performance, torque-speed characteristics, no-load and blocked-rotor tests, equivalent circuit, starting and speed control · 1 mark · Multiple choice

The following columns present various modes of induction machine operation and the ranges of slip

A: Mode of operationB: Range of slip
a. Running in generator modep) From 0.0 to 1.0
b. Running in motor modeq) From 1.0 to 2.0
c. Plugging in motor moder) From −1.0 to 0.0

The correct matching between the elements in column A with those of column B is

  1. a-r, b-p, and c-q
  2. a-r, b-q, and c-p
  3. a-p, b-r, and c-q
  4. a-q, b-p, and c-r

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Show answer and explanation

Correct answer: (A) a-r, b-p, and c-q

Explanation

Generator mode is above synchronous speed, so the slip is negative (−1 to 0): a–r. Motor mode has slip 0 to 1: b–p. Plugging (rotor driven against the field) has slip 1 to 2: c–q.