6. A 30 MVA generator with 15% reactance is connected to a bus bar. A 25...

6. A 30 MVA generator with 15% reactance is connected to a bus bar. A 25 MVA transformer with 10% reactance is also connected through a 10% bus bar reactor to the same bus bar. Both of these reactance is based on 25 MVA. If a feeder taken out from the bus bars through a circuit breaker develops a three-phase fault, what should be the appropriate rating of the circuit breaker?

7. A system operates at 220 kVA and 11 kV. Using these quantities as base values, find the base impedance for the system.

Expert Solution

Manojponduru answered 10 months ago

1 unit generator and motor syncron with rating 25 MVA, 13,2 KV. both have subtransien reactance...

1 unit generator and motor syncron with rating 25 MVA, 13,2 KV. both have subtransien reactance 15%. reactance 10% to machine base. motors rating 20 MW (0.9 lagging) and terminal voltage 12,5 KV. 3 phase fault occurs at the generator terminal. calculate the subtransient generator currents, motor subtransient currents and symmetrical fault currents using thevenin theorem

QUIESTION 1 A three-phase synchronous generator is connected to an infinite bus. The infinite bus voltage...

QUIESTION 1 A three-phase synchronous generator is connected to an infinite bus. The infinite bus voltage and the generated voltage are o 1.0 pu ∠0 and o 1.0pu ∠42.84 , respectively. The synchronous reactance is 0.85 pu and resistances are neglected. a) Compute power angle (δ), armature current (Is), power factor (pf), real power (P), and reactive power (Q). Draw the phasor diagram. b) If the prime mover torque is kept constant at a value corresponding to P=0.8 pu, compute...

6.9 A3 ϕ, 11 kV, 60 Hz, 25 MVA, Y-connected cylindrical-rotor synchronous machine generator has Ra...

6.9 A3 ϕ, 11 kV, 60 Hz, 25 MVA, Y-connected cylindrical-rotor synchronous machine generator has Ra = 0.45 Ω per phase and Xs = 4.5 Ω per phase. The generator delivers the rated load at 11 kV and 0.85 lagging power factor. Determine the excitation voltage, Ef, for this operating condition. 6.11 The synchronous machine in Problem 6.9 is operated as a synchronous motor and it is drawing rated MVA at 0.85 lagging power factor. Determine the excitation voltage, Ef,...

Bus Data,Generator Data and Line Data for IEEE 30 Bus System in (p.u)

8. Three 6.6 kV, 12 MVA, 3-phase alternators are connected to a common bus bars. Each...

8. Three 6.6 kV, 12 MVA, 3-phase alternators are connected to a common bus bars. Each has reactance to positive sequence current of 15%. The reactance to negative and zero sequence current are 75% and 30% of the positive sequence value. If an earth fault occurs on one of bus bar, determine the fault current when one of the alternator neutral is earthed through a resistance of 0.25 ohm and the others are isolated. 9. Four identical alternators each rated...

A 1000MVA, 20kV, 60 Hz three phase generator is connected to an infinite bus through a...

A 1000MVA, 20kV, 60 Hz three phase generator is connected to an infinite bus through a 1000MVA, 20kV? / 345kVY transformer to a 345kV circuit breaker and a 345kV transmission line. The generator reactances are X``d=0.17, X`d=0.30, and Xd=1.5 per unit on a 1000MVA, 20kV base. Generator time constants are T``d=0.05 seconds, T`d=1.0 seconds, and TA=0.10 seconds. The transformer series reactance is 0.10 per unit on the transformer ratings as a base. Neglect transformer losses, excitation current, and transformer time...

1- A 480-V, 60-Hz, delta connected, synchronous generator has a synchronous reactance of 0.5 ohm and...

1- A 480-V, 60-Hz, delta connected, synchronous generator has a synchronous reactance of 0.5 ohm and Its rated Line current is 100 A. if the generator is connected to a 480V grid Draw the phasor diagram and find EA, delta angle and output power under the following conditions a- The generator supply the rated current at 0.8 PF lagging. b-The generator supply the rated current at 1.0 PF. c- The generator supply the rated current at 0.8 PF leading.

Consider the classical power system where one generator is connected to the infinite bus through two...

Consider the classical power system where one generator is connected to the infinite bus through two transmission lines. We want to study the transient stability for a fault on one of the two lines. The generator parameters are as follows: Pm = 1, H = 4, KD = 5, x'd = 0.25, E' =1.4. The transmission line where the fault occurs has a line reactance of 0.6 pu. The other transmission line that remains in service has a line reactance...

A three phase, 60 Hz, 480 V, Y-connected, two-pole synchronous generator has a synchronous reactance of...

A three phase, 60 Hz, 480 V, Y-connected, two-pole synchronous generator has a synchronous reactance of 0.95 Ω per phase. Its armature resistance is negligible. Its combined friction and windage losses are 1.3 kW and its core losses are 0.95 kW. The field current is constant at no-load. Its full load armature current is 55 A at 0.9PF lagging. Assume phase voltage is a reference. Determine following: a) Its terminal voltage when it is loaded with the rated current at...

A 480 V, 50 Hz, Y-connected six-pole synchronous generator has a per-phase synchronous reactance of 1.0...

A 480 V, 50 Hz, Y-connected six-pole synchronous generator has a per-phase synchronous reactance of 1.0 Ω. Its full-load armature current is 60 A at 0.8 PF lagging. Its friction and windage losses are 1.5 kW and core losses are 1.0 kW at 60 Hz at full load. Assume that the armature resistance (and, therefore, the I2R losses) can be ignored. The field current has been adjusted such that the no-load terminal voltage is 480 V. a. What is the...

Question