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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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Governor dead bad cause due to
Mechanical friction
Backlash
Valve overlaps in hydraulic relays
All of above
All of above
Quick Summary: The dead band of a governor is the range of frequency or speed variations within which the governor does not respond to initiate a change in fuel input. This lack of sensitivity is primarily caused by internal mechanical constraints, clearances, and time lags that prevent the governor from acting on small changes.
The dead band of a governor is the range of frequency or speed variations within which the governor does not respond to initiate a change in fuel input. This lack of sensitivity is primarily caused by internal mechanical constraints, clearances, and time lags that prevent the governor from acting on small changes.
DeadBand=Δflimit — The frequency range over which governor action is inhibited.
Mechanical friction in the governor linkages resists initial movement, requiring a certain threshold force before the mechanism responds. Backlash in gears or linkages introduces a 'play' where movement in one direction does not immediately result in corresponding movement in the output. In hydraulic relays, valve overlaps ensure that the control port remains closed at a neutral position, creating a range where input changes result in zero output displacement.
Dead band is a measure of the sensitivity of a governor.
A wider dead band reduces the stability of the system but prevents excessive 'hunting' of the governor during minor fluctuations.
Modern digital governors aim to minimize the dead band for tighter frequency control.
Prevents unnecessary wear of the governing mechanism.
Reduces hunting or oscillations in the turbine speed.
Leads to poor frequency regulation in power systems.
Reduces the responsiveness of the unit to load changes.
Thermal Power Plant Turbine Speed Control
Hydro-electric Unit Frequency Regulation
Option A (Mechanical friction) introduces static resistance.
Option B (Backlash) introduces a zone of zero movement in transmission.
Option C (Valve overlaps) ensures stability but inherently creates a null zone.
The dead band should typically be kept within 0.05% to 0.1% of rated speed.
D is correct — The dead band of a governor is a cumulative effect caused by mechanical friction, backlash in moving parts, and overlap in hydraulic control valves.
In competitive exams, remember that any factor limiting the 'input-to-output' motion of a control element is a contributor to dead band or dead zone.