ISRO Scientist or Engineer Electrical 2018
For the following questions answer them individually
A 4 kVA, 400 V/200 V single phase transformer has resistance of 0.02 p.u and reactance of 0.06 p.u. The resistance and reactance referred to HV side are
A 100/5 A bar primary current transformer supplies an overcurrent relay set at 25% pick up and it has a burden of 5 VA. The secondary voltage is
The distribution system indicated below is to be protected with over current protection. Identify the locations where essentially directional over current relays will be required considering proper fault discrimination.
Impedance of single phase, two winding transformer referred to primary side is 0.1 + j 0.6 p.u. The rating of the transformer is 200 $$\frac{V}{400}$$ V, 1 kVA. The per unit impedance is calculated on transformer base, then what is the equivalent impedance of transformer referred to secondary in ohms?
A schematic diagram of an alternator is shown below where $$V_{an} = V_{bn} = V_{cn} = V_1$$
If a single phase to ground fault occurs at location ‘a’, what will be the voltage at ‘b’ and ‘c’?
Which among the following are suitable for improving the transient stability limits of a power system?
i. Increase system voltage by AVR
ii. Use high speed excitation systems
iii. Use high speed reclosing breakers
iv. Increase system frequency
The $$Y_{bus}$$ matrix of a 100 bus interconnected system is 80% sparse. Then, the number of transmission lines in the system must be
What is the size of a Jacobian matrix for a 100 bus power system with 29 nos. of voltage controlled buses?
