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 12) at its connection box. Draw the schematic for this motor connected in;
i. Series star
ii. Parallel delta
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
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
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...
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-...
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...
Three single-phase transformers are connected in delta-delta configuration to step up a line voltage of 8 kV to 120 kV. A 24 MVA load at angle 30 is connected to the high voltage side. Calculate: a) Transformer turns ratio b) Load power in MW c) Line current in HV and LV sides d) The apparent power supplied by each transformer e) If one transformer is removed for maintenance, what is the reduction percentage in the transformer bank power rating with...
Three single-phase transformers are connected in a wye-delta configuration to step down a line voltage of 13.8kV to 4160V to supply an industrial facility. The plant draws 8MW at a 0.80 power factor. Transformer impedances can be neglected. Calculate the following: a. the apparent power (SL) drawn by the load/plant. b. the apparent power (Ss) furnished by the HV source. c. the current in the HV lines (141) d. the current in the LV lines (112) e. the currents in...
2. In order to meet an emergency, three single-phase transformers rated 100 kVA (each), 13.2 kV/2.4 kV are connected in Y-∆ on a 3-phase, 20 kV line. a. What is the maximum load that can connected to the transformer bank? b. What is the outgoing line voltage?
A transformer bank is made up of three single-phase transformers rated 240/360/400MVA, 500kV wye-grounded / 24kV delta. The impedance of each transformer is 12.3% on base MVA. a. What is the impedance of the transformer bank in per-unit on 100MVA? b. What is the impedance of the transformer bank in 500kV ohms? c. What is the maximum three-phase fault current available on the 24kV bus (assuming a source connected to the 500kV winding and no source connected to the 24kV...
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 3-phase transformer 50 MVA, having line-voltage ratio of 11 kV/33kV is connected in star-delta What must be the ratio of the protective transformers on the both sides?