Join 60,000+ competitive exam aspirants
or with email
Your Cart
Subtotal₹0
Total₹0
Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
Join 60,000+ competitive exam aspirants
The function of speed changer is
Change the speed of governor
Limit the speed of governor
Steady state power output of turbine
All of above
Steady state power output of turbine
Quick Summary: The speed changer, also known as the speeder motor or load-limit controller, is a mechanism that adjusts the spring tension or the reference position of the governor. By changing the governor's operating point, it effectively regulates the turbine's steady-state power output while the system frequency remains within the droop characteristic.
The speed changer, also known as the speeder motor or load-limit controller, is a mechanism that adjusts the spring tension or the reference position of the governor. By changing the governor's operating point, it effectively regulates the turbine's steady-state power output while the system frequency remains within the droop characteristic.
f=fref−Kp⋅P
ΔP=R1(Δf)
In a governor system with a droop characteristic, the speed changer shifts the parallel speed-load curve vertically. By adjusting the speeder spring, the governor senses a new reference speed, thereby changing the fuel or steam input to the prime mover to achieve a new steady-state power load without changing the system frequency.
The speed changer is essential for load frequency control (LFC) in power systems.
It allows operators to dispatch power from a plant without waiting for frequency deviations.
It effectively provides a vertical shift to the f−P (Frequency-Power) droop curve.
Synchronous generators must be synchronized to the grid before the speed changer can adjust load.
Enables precise economic dispatch of power plants.
Allows real-time adjustment of unit generation according to load demand.
Limited by the physical range of the turbine valves or gates.
Does not affect the inherent droop constant of the governor.
Hydroelectric power plants.
Thermal power plants.
Grid frequency regulation.
The speed changer is physically a motor-operated adjustment on the speeder spring of a flyball or electronic governor.
Option A is incorrect because the speed changer modifies the setpoint of the governor, not the speed of the governor mechanism itself.
Option B is incorrect because limiting the speed is the function of an overspeed protection device, not the speed changer.
C is correct — The speed changer adjusts the governor's setpoint, thereby controlling the steady-state power output of the turbine.
Always distinguish between primary frequency control (automatic response to frequency change) and secondary control via the speed changer (manual or remote load adjustment).