2018-19
- Name the symmetrical and unsymmetrical faults.
- A generator supplying an unbalanced load measures the following phase to ground voltages. Va = 16.0∟00 KV, Vb = 15.0∟-1520 KV, Vc = 10.0∟1000 KV. Find the symmetrical components of the set of phase voltages.
- What do you understand by instantaneous maximum momentary current for line? Explain it with the help of suitable diagram and drive condition of doubling effect.
- For a single line to ground fault at the terminals of an unloaded generator, positive sequence current was found to be 50 A. Determine sequence currents in phase b and c.
2017-18
- Derive the relationship to determine the fault current for a single line to ground fault. Draw an equivalent network showing the interconnection of sequence networks to stimulate LG fault.
2016-17
- Rank the various faults that can occur in power system in the order of severity.
- Prove that 1+ α + α2 = 0. The symbols having their usual meanings.
- Define the symmetrical components.
- Discuss the principle of the symmetrical components. Derive the necessary equation to convert phase quantities into symmetrical components
- The line to ground voltages on the high voltage side of a step up transformer are 100 KV, 33 KV and 38 KV on phases a, b and c respectively. The voltage of phase a leads that of phase b by 1000 and lags that of phase c by 176.50. Determine analytically the symmetrical components of voltage.
- Derive the expression for the symmetrical components of fault current of a power system for L-L fault through impedance. A 30 MVA, 11 KV generator has Z1=Z2= j0.2 pu, Z0=j0.05 pu. A-line to ground fault occurs on the generator terminals. Find the fault current and line to line.
2015-16
- The neutral grounding irnpedance Znappears as 3Zn in the zetro-sequence equivalent circuit why?
- Name the fault current in wtrich all the three sequence currents are present and are equal.
- Prove that zero sequence network is absent in case of ocrurence of double line fault through certain impledance in a power system network. Draw the zeto sequence network for the system shown below in figure
