Governors free study notes

1. Introduction to Governors

A governor is a mechanical device used to regulate the mean speed of an engine by automatically adjusting the fuel supply when the load varies.

Key Idea

• Maintains constant average speed
• Works during load variations
• Different from flywheel (which controls speed fluctuation within a cycle)

2. Function of Governors

• Maintain constant engine speed
• Adjust fuel/steam supply automatically
• Improve operational stability
• Prevent over-speeding

3. Principle of Working

Governors work on the principle of centrifugal force.

$F_c = m \omega^2 r$Fc​=mω2r

Where:

• $F_c$Fc​ = centrifugal force
• $m$m = mass of rotating balls
• $\omega$ω = angular velocity
• $r$r = radius of rotation

Working Mechanism

• Speed increases → balls move outward
• Sleeve moves upward → reduces fuel supply
• Speed decreases → balls move inward
• Sleeve moves downward → increases fuel supply

4. Types of Governors

A. Centrifugal Governors

(a) Watt Governor

6

• Oldest type
• Used in low-speed engines
• Simple construction

(b) Porter Governor

5

• Central load added to sleeve
• More sensitive than Watt governor
• Suitable for moderate speeds

(c) Proell Governor

• Similar to Porter
• Balls rotate at lower radius
• Better stability

B. Inertia Governors

• Work on inertia forces instead of centrifugal force
• Less commonly used

C. Spring-Controlled Governors

(a) Hartnell Governor

7

• Uses spring instead of weights
• Compact design
• Used in high-speed engines

(b) Hartung Governor

• Similar to Hartnell
• Different spring arrangement

5. Height of Governor

For Watt governor:

$h = \frac{g}{\omega^2}$h=ω2g​

Where:

• $h$h = height of governor
• $g$g = acceleration due to gravity

6. Characteristics of Governors

(a) Stability

• Governor is stable if speed increases with radius

(b) Sensitivity

$$\text{Sensitivity} = \frac{N_{mean}}{N_{max} – N_{min}}$$

• Higher sensitivity → better response

(c) Isochronism

• Governor runs at constant speed for all radii
• Ideal but impractical

7. Effort and Power of Governor

Governor Effort

• Force required to change sleeve position

Governor Power

• Work done at sleeve

$$\text{Power} = \text{Effort} \times \text{Lift}$$

8. Hunting in Governors

8

• Continuous oscillation of sleeve
• Caused by over-sensitivity
• Leads to unstable operation

9. Governor vs Flywheel

Feature	Governor	Flywheel
Function	Controls mean speed	Controls speed fluctuation
Principle	Centrifugal force	Energy storage
Action	Regulates fuel supply	Stores/releases energy

10. Advantages of Governors

• Automatic speed control
• Prevents engine damage
• Improves efficiency
• Maintains steady operation

11. Disadvantages

• Complex mechanism
• Requires maintenance
• Less effective for rapid changes

12. Applications of Governors

• Steam engines
• IC engines
• Turbines
• Diesel generators
• Industrial machinery

13. Key Exam Points

• Derivation of height of Watt governor
• Difference between Watt, Porter, Hartnell
• Concept of sensitivity and stability
• Hunting and its causes
• Numerical problems

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