Power Systems

Use this for “On a 138 kV, 100 MVA base, what is a 19.04 Ω line impedance in per unit?”

Use this for “A generator is 0.1 pu on its 50 MVA rating. What is that on the 100 MVA system base at the same kV?”

Use this for “A line with R = 0.02 pu and X = 0.1 pu delivers P = 0.8 pu and Q = 0.6 pu at 1 pu. Find the sending voltage.”

Use this for “A 33 kV line carries 10 MW at power factor 0.9 with 5 Ω per phase. Find the current and the loss.”

Use this for “A 50 kVA transformer has 300 W of core loss and 600 W of full-load copper loss. Find its efficiency at full load, pf 0.8.”

Use this for “A 240 V DC motor draws 20 A, with Rₐ = 0.5 Ω and kΦ = 2.3 V·s/rad. Find its speed and torque.”

Use this for “A generator delivers 100 A at pf 0.8 lagging and 277 V per phase, with Xₛ = 1 Ω. Find E and δ.”

Use this for “X₁ = X₂ = 0.2 pu and X₀ = 0.1 pu. Find the line-to-ground fault current on a 100 MVA, 13.8 kV base.”

Use this for “A bus has 500 MVA of short-circuit power available. Find Xₜₕ on a 100 MVA base.”

Use this for “Iₐ = 10∠10° A, Ib = 8∠−100° A and Ic = 6∠140° A. Find the zero-, positive- and negative-sequence currents.”

Use this for “A generator with 5% droop picks up 0.1 pu more load on a 60 Hz system. How far does the frequency fall?”

Use this for “A grid with H = 5 s loses 0.1 pu of generation at 60 Hz. How fast does the frequency start to fall?”

Use this for “A generator with H = 5 s runs at δ₀ = 30° with Pₘₐₓ = 2 pu on a 60 Hz grid. Find its swing frequency.”