Design the differential protection for three phase 50Hz transformer with the following ratings: 250MVA, 15.75kV/400 kV,...
A 100 MVA, 66 kV/230 kV, Delta- Wye three phase transformer is protected by a differential relay. Current transformer ratio at the LV side is 1000 :5 A. a) Sketch connection of differential relays to the transformer b) Current transformers available for use at the HV side are 800:5, 600:5, 400:5 and 200:5. Select the suitable CT ratio. c) Sketch the phasor diagram to show currents in current transformers windings and power transformers windings d) Calculate the percentage of the...
The ratings of a three-phase, three-winding transformer are Y connected, 66 kV, 20 MVA Primary (1): Secondary (2):Y connected, 13.2 kV, 15 MVA Tertiary (3): A connected, 2.3 kV, 5 MVA Neglecting winding resistances and exciting current, the per-unit leakage reactances are: X12 0.08 on a 20-MVA, 66-kV base X13 0.10 on a 20-MVA, 66-kV base X23 0.09 on a 15-MVA, 13.2-kV base (a) Determine the per-unit reactances Xi, X2, X3 of the equivalent circuit on a 20- MVA, 66-kV...
A three-phase Y-A transformer is rated 225-kV:24-kV, 400 MVA and has a single-phase equivalent series reactance of 6.08 ? as referred to its high-voltage terminals. The transformer is supplying a load of 375 MVA at 0.89 power factor leading at a voltage of 24 kV (line to line) on its low-voltage side. It is supplied from a feeder whose impedance is 0.17 +/2.2 ? connected to its high-voltage terminals. For these conditions, calculate (a) the line-to-line voltage at the high-...
A three-phase transformer bank is rated at 500 kVA and have a 34.5/12 kV voltage ratio. Find the following ratings of each individual transformer in the bank when the transformer is ∆-Y connected: high voltage, low voltage, turns ratio (a), and apparent power.
Transformer TI : 50 MVA, 10 kV Y/138 kV Y, X=0.10 per unit; Transformer T2: 100 MVA, 15 kV D/138 kV Y, X-0.10 per unit; Each 138-kV line: X1-400 A three-phase short circuit occurs at bus 5, where the prefault voltage is 15 kV. Prefault load current is neglected. (a)Draw the positive-sequence reactance diagram in per-unit on a 100-MVA, 15-kV base in the zone of generator G2. Determine: (b) the The'venin equivalent at the fault, (c) the subtransient fault current...
A 400-MVA, 200-kV/20-kV, three phase Y-Y transformer has an equivalent series impedance of ZTL = 0.012 + 20.0162 per phase referred to the low-voltage side (secondary side). The transformer is supplying a three-phase load of 300-MVA, 0.8 power factor lagging at terminal voltage of 20 kV (line-to-line) on its low-voltage side (secondary side) as shown in Fig. 22. The primary is supplied from a transmission line with an impedance of ZL = 0.5 + j1.0 per phase. The line-to-neutral load...
how to design a differential protection on a transformer using simulink on matlab?
Problem 3. A three-phase transformer is constructed using three single-phase two-winding trans- formers, each has the same ratings of 500 MVA, 15/240 kV, and leakage impedance of XT.p.u 0.2 p.u The high-voltage side of the three-phase transformer is connected to a three-phase Y-connected load that absorbs 1000 MVA at 0.9 power factor (lagging). The phase-a voltage across the load is Van 2402(0) kV. Answer the following questions. [10 points] a) Calculate the phase-a voltage at the low-voltage side (denoted by...
A 3 phase transformer bank is rated at 500 kVA and has a 34.5/11 kV voltage ratio. Find the following ratings of each individual transformer in the bank when the transformer is wye to Delta connected : High voltage, low voltage, turns ratio, and apparent power
1. A three-phase synchronous generator connected to a 345-KV transmission line through a transformer as shown in Figure P1. Parameters of both generator and transformer are given in the figure. Transformer losses and exciting current are neglected. A three-phase short-circuit occurs on the line side of the circuit breaker when the generator is operated at rated terminal voltage and at no-load. The breaker interrupts the fault three cycles after fault inception. Neglect the effect of the transformer on the time...