A delta-wye connected transformer is shown in Figure below. This is a 220 kV to 450...
Problem 4 Three ideal single-phase transformers are connected in a delta/wye configuration with the primary side of the three-phase transformer rated at 120 kV and the secondary side rated at 13.8 kV. The rated power of the transformer bank is 20 MVA. One side of the transformer bank is connected to a 120 kV transmission line, and the other side is connected to a three-phase load of 15 MVA at 0.85 lagging power factor. Compute the following: a) The turns...
What is the answer for questions 2-5?
Questions: 1. Delta-Wye and Wye-Delta configurations both produce: a) Increases in secondary voltages and currents. b) Decreases in the secondary voltages and currents. c) Phase shift between the incoming and outgoing line voltages. d) Additional V3 increases in the secondary voltages and currents. ANSWER: Choose an item. 2. The line voltage at the secondary of a 10:1 wye-delta connected transformer will be: a) Equal to the line voltage at the primary times b)...
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...
1. Three single-phase step-up transformers rated at 75 MVA, 13.2 kV/80 kV are connected in delta- wye on a 13.2 kV transmission line. If they feed a 180 MVA load, calculate the following: a. The secondary line voltage b. The currents in the primary and secondary windings C. The incoming and outgoing transmission line currents
a. Three single phase step-up transformers rated at 40 MVA, 13.2 kV/80 kV are connected in delta-wye on a 13.2 kV transmission line. If they feed a 90 MVA load calculate the following: i. The secondary line voltage ii. The current in the transformer windings iii. The incoming line currents iv. If the transformer types are two (2) additive and one (1) subtractive draw the connection diagram for the configuration stated using physical representation. b. A 3-phase squirrel cage motor has twelve (12) leads (labelled 1 to...
1. In order to meet an emergency, three single-phase transformers with 12.470/7.200 V are connected in Delta-Wye to form a three-phase transformer which is fed by a 12.470 V transmission line. If the transformer supplies 60 MVA to a load, calculate: (3 marks) a. The turns ratio for each transformer b. The currents in the primary and secondary windings of the transformer c. The primary and secondary transmission line currents 2. A Wye-Delta transformer is connected to a 66 kV...
A balanced three-phase network supplies a balanced load through a three-phase wye-wye connected transformer as shown in the following figure. Transformer Supply Network B8 Load Y-Y The wye-wye connected transformer has the following parameter: S 25 MVA Xir 15% 240/132 kV The three-phase load parameters are: Pload 20 MW pfload 0.8 The three-phase supply network line voltage and short circuit current are: Vnet 225 kV Inet_short= 15 kA. A. Calculate primary and secondary current rating. B. Calculate trans former actual...
What is the magnitude of the primary line current of a 14,000 – 480Y/277 V, delta-wye, three- phase distribution transformer if a 200kW, 0.88 P.F. lagging load is connected to the secondary. (assume that the transformer is lossless and that the primary is the high-voltage side)
Three single-phase transformers rated at 250 kVA, 7200 V/600 V, 60 Hz, are connected in wye- delta on a 12.47 kv, 3-phase line. If the load is 450 kVA, calculate: a. The currents in the incoming and outgoing transmission lines b. The currents in the primary and secondary windings 1. sratod t 200 w 3o0 v/6oO V 60 Hz are used to raise the
Three single-phase transformers rated at 250 kVA, 7200 V/600 V, 60 Hz, are connected in wye-...
Problem 1: A three-phase transformer has the following name plate data: Rated Power Primary voltage Secondary Voltage Excitation reactance Series Impedance 150 MVA 230 kV 32 kV 30 (pu) 0.02+0.15j (pu) The transformer is Y/A connected. Answer the following questions: a) What are the nominal (rated) primary and secondary line currents?| b) What is the nominal value of the Delta-side winding (internal) current? c) What is the secondary to primary winding turn ratio? d) The transformer is supplying 150 MVA...