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
Which of this power plant is started first after system black out
Thermal
Nuclear
Hydro
All of above
Hydro
Quick Summary: Hydro power plants are utilized as 'black start' units because they can be started independently without requiring an external electrical supply. Unlike thermal or nuclear plants, which require auxiliary power to run boilers, feed pumps, and cooling systems, hydro plants rely on gravity-fed water to rotate turbines.
Hydro power plants are utilized as 'black start' units because they can be started independently without requiring an external electrical supply. Unlike thermal or nuclear plants, which require auxiliary power to run boilers, feed pumps, and cooling systems, hydro plants rely on gravity-fed water to rotate turbines.
P=ηρgQH — Power output equation where P is power, η is efficiency, ρ is density, g is gravity, Q is flow, and H is head.
In a black start scenario, the governor system of a hydro turbine uses a small battery-powered actuator to open wicket gates. As water flows through the turbine, it spins the generator, producing voltage to build up the system frequency. Once stable, this 'cranking' power is used to energize transmission lines to restart larger, non-self-starting thermal plants.
Black start capability refers to the ability of a power plant to start without support from the external grid.
Thermal plants require 'cranking power' for boiler feed pumps, fans, and cooling systems.
Hydro units possess high inertia and fast-start characteristics suitable for grid restoration.
Diesel generators or gas turbines can also serve as black-start units in some grid configurations.
Independent startup capability
Rapid response to grid frequency fluctuations
Essential for restoring power during total collapse
Geographically limited to sites with water reservoirs
High initial infrastructure cost
Dependent on hydrological availability
Grid restoration after major blackout
Emergency supply for local distribution grids
A 'Black Start' unit acts as a 'reference' source for the grid during the restoration phase.
Option A (Thermal) is incorrect because boilers require electricity for startup.
Option B (Nuclear) is incorrect due to stringent safety regulations and massive auxiliary power requirements.
C is correct — Hydro power plants serve as the designated black start source due to their ability to start without an external electrical grid connection.
Always remember that 'self-starting' ability is defined by the absence of need for external excitation or motor-driven auxiliaries, which is the defining characteristic of Hydro and some Gas/Diesel plants.