2018-19
- Draw the zero sequence network of delta-delta connection.
- Discuss the representation of a power system network by reactance diagram show that the per unit impedance of a transformer computed from primary or secondary side is same if the voltage base on two sides are in the ratio of transformation.
- Discuss the various stragic location aspects of reactors of limiting the fault current and their advantages.
- A 200 MVA, 11 KV, 3-phase generator has a sub-transient reactance of 10%.The generator supplies a number of synchronous motors over a 34 KM transmission line having transformers at both end in one line diagram. The motors all rated 12.2 KV, represented by just two equivalent motors. Rated inputs to the motors are 300 MVA and 200 MVA for M1 and M2 respectively. For both motors XII = 30%. The three phase transformers T1 is rated 350 MVA, 220(delta)/11(star grounded) KV with leakage reactance of 10%. Transformer T2 is composed of three single phase transformers each rated 127(star grounded)/12.2(delta) KV, 300 MVA with leakage reactance of 10%. Series reactance of transmission line is 0.2 Ω/KM. Draw the reactance diagram with all reactance’s marked in per unit. Select the generator rating as base in generator circuit.
2017-18
- What is impedance and reactance diagram?
- Define sub-transient reactance.
- Write a short note on feeder reactors.
- One conductor of a 3-phase line is open. The current flowing to the delta connected load through line ‘a’ is 10 A. With the current in the line ‘a’ as reference and assuming that line ‘c’ is open. Find the symmetrical components of the line current
- Explain the sequence impedances. Define balanced star connected load and transmission lines of sequence impedances.
- Obtain per unit reactance diagram of the power system shown in figure.
