Question

In power transmission slip is usually expressed as the percentage of

• A. Speed enhancement
• B. Speed reduction
• C. Power enhancement
• D. Power reduction

Hint:

Think of "slip" in everyday terms. If you try to run on ice, your feet "slip," and you don't move forward as fast as you intend. In mechanics, it's the same idea: the driven part doesn't quite keep up with the driver, leading to a speed reduction.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The question is about the concept of 'slip' in power transmission systems, particularly in belt drives or induction motors. Slip refers to the difference between the theoretical speed (synchronous speed in motors, or the speed of the driving pulley's surface in a belt drive) and the actual speed of the driven component.

Step 2: Detailed Explanation:
In any practical power transmission system like a belt drive, there is always some loss of motion due to factors like the stretching of the belt, insufficient friction, or air resistance. This results in the driven pulley rotating at a slightly lower speed than what would be theoretically expected based on the driver pulley's speed and the pulley diameters.
This difference in speed is called 'slip'. It represents a loss or reduction in speed.
The formula for slip percentage in a belt drive is often given as:
\[ S(\%) = \frac{N_1 - N_2'}{N_1} \times 100 \] where \(N_1\) is the speed of the driver pulley and \(N_2'\) is the actual speed of the driven pulley. The term \(N_1 - N_2'\) clearly represents the speed reduction.
Similarly, in an AC induction motor, slip is the difference between the synchronous speed of the magnetic field and the actual rotor speed, which is always less. This is also a form of speed reduction.
Therefore, slip is fundamentally a measure of the percentage of speed that is lost or reduced during transmission.

Step 3: Final Answer:
Slip is expressed as the percentage of speed reduction.