Question

Consider the following statements regarding capability curves of a synchronous generator:

1. The MVA loading should not exceed the generator rating.

2. The field current should not be allowed to exceed a specified value determined by field heating.

3. The MW loading should not exceed the rating of the prime mover.

4. The load angle must be more than 90°.

Which of the above statements are correct?

1. 1, 2, 3 and 4
2. 1 and 4 only
3. 1, 2 and 3 only
4. 2, 8 and 4 only

Answer 1

Correct Answer - Option 3 : 1, 2 and 3 only

• The capability curve of a synchronous generator defines a boundary within which the machine can operate safely.
• It is also known as operating charts or capability charts.
• Machines are designed to operate within certain specified limits.
• The MVA loading should not exceed the generator rating, hence statement-1 is true.
• The field current should not be allowed to exceed a specified value determined by the heating of the field, hence statement-2 is true.
• The MW loading should not exceed the rating of the prime mover, hence statement-3 is true.
• For steady-state or stable operation the load angle δ < 90°, hence statement-4 is false.
• Therefore, statement 1, 2 & 3 are correct.