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 current through the operating
coil under full load condition of the transformer
A 100 MVA, 66 kV/230 kV, Delta- Wye three phase transformer is protected by a differential...
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...
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...
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...
A delta-wye connected transformer is shown in Figure below. This is a 220 kV to 450 kV transformer, line-line, RMS. The 'X' side is the 220 kV side. Assume that Phase A voltage on the X' side has zero phase angle (that is, use VaX as the phase reference) 1) What is the turns ratio NX: NH? 2) Draw phasor diagrams of the primary and secondary voltages. Be sure to get relative phase angles right. 3) If a balanced load...
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...
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?
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-...
select one Best match
11) A 12 kV radial system is given below, Assuming using relay CO-7, 3 cycles breaker operation time and 0.5 second coordination time delay, what are the best settings to protect the system shown below: (10 points) 12 kV Typical time curves ype Co-7 C.T.R-400/5 C.T.R-200/5 Current tap settings: 4.5,6,78,10,12 amperes 4 MVA Isc-1.6 kA 4 MVA Isc-1.2 kA Time dial TS1 TDS1 TS2 TDS2 A) 51/252 B) 41/24 C) 51/25 D) 41/24 2 4 5...
A 5 MVA 230/13.8 kV, single-phase transformer has a per-unit resistance of 1% and a per-unit reactance of 5%. The open-circuit test performed on the low voltage side of the transfromer yielded the following data: VOC=13.8 kV, IOC=21.1 A, and POC=90.8 kW. (a) Find the equivalent circuit referred to the high voltage side of this transformer. (b) If the transformer is operating at full-load and at 0.8 pf lagging, find the voltage regulation of the transformer at this operating condition.