Question

Comment on the speed of generators of Chandrapur Super Thermal Power Station and Koyana Hydro Power Station.
1. Same speed of both power station generators
2. Chandrapur Super Thermal Power Station generator speed is higher
3. Koyana Hydro Power Station speed is higher
4. Cannot comment

Answer 1

Correct Answer - Option 2 : Chandrapur Super Thermal Power Station generator speed is higher

Concept:

• A hydro generator normally runs at a very lower speed as compared to steam turbines
• A hydroelectric generator has many more poles and therefore runs much slower at around 300 rpm
• Normally a hydro generator has more than 24 poles and thus speed required to attain desired frequency is less
• Turbo-generator which is used in nuclear and steam (thermal) power plants runs at very high speed around 3000 rpm

 

Explanation:

As the speed of the alternator used in thermal power plant is higher compared to the speed of the alternator used in hydro power station, Chandrapur Super Thermal Power Station generator speed is higher.

Important Points:

• Non-salient pole type rotors are used in high-speed alternators or turbo-alternators having speed between 1500 rpm to 3000 rpm.
• Salient pole rotors are used in low-speed devices, from 100 rpm to 1500 rpm.