Question 4 A 100 MVA, 66 kV/230 kV three phase transformer is protected by a differential relay. A 1000 /5 current transformer is installed at the 66 kV side. Select suitable current transformer for the HV side of the transformer (available CT ratio are 1000/5, 800/5, 600/5, 400/5). Calculate the currents through operating and restrain coils

Question 4 A 100 MVA, 66 kV/230 kV three phase transformer is protected by a differential relay. A 1000 /5 current transformer is installed at the 66 kV side. Select suitable current transformer for the HV side of the transformer (available CT ratio are 1000/5, 800/5, 600/5, 400/5). Calculate the currents through operating and restrain coils

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.10P: A single-phase step-down transformer is rated 13MVA,66kV/11.5kV. With the 11.5 kV winding...

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For a short-circuit test on a 2-winding transformer, with one winding shorted, can you apply the rated voltage on the other winding? (a) Yes (b) No
The ratings of a single-phase three-winding transformer are as follows:*primary winding: 300 MVA, 14kV*secondary winding: 300MVA, 200kV*tertiary winding: 40MVA, 20kV. The leakage reactances are:*Xps = 0.1 at 300MVA, 14kV*Xpt = 0.16 at 40MVA, 14kV*Xst = 0.14 at 50MVA, 200kV Neglecting the winding resistance and exciting current, calculate Xp, Xs and Xt using 300 MVA and 14kV as the base for the primary winding.
The equivalent circuit impedances of a 20-kVA, 8000/240-V, 60-Hz transformer are to be determined. The open-circuit test and the short- circuit test were performed on the primary side of the transformer, and the following data were taken: Open-circuit test (on primary) Short-circuit test (on primary) 8000 V V= 489 V I0.214 A 2.5 A P= 400 W P= 240 W Find the impedances of the approximate equivalent circuit referred to the primary side, and sketch the circuit.
In the single-phase, three- winding, transformer, the primary current is equal to lo at the condition of ints there is no load on tertiary windings the current in secondary windings equal to zero the resistances (R1, R2, and R3) in transformer windings are equal the inductances (L1, L2, and L3) in transformer windings are equal.
Two transformers A and B have the following data Transformer A: 6600/440 V, (250 KVA ) requires ( 6%) of rated voltage to circulate (90%) of full load current at power factor (0.25) when the low voltage winding is short circuited and the no load loss is equal to (2500 W). Transformer B: 6600/420 V, (600 KVA) requires (9%) of rated voltage to circulate (80%) of full load current at power factor (0.16) when low voltage winding is short circuited and no load loss is equal to (4500 W). Calculate the followings: If both transformers are connected in parallel to supply a load (1.2 + j 2.3) ohm, find the output power of each transformer.
Two transformers A and B have the following data Transformer A: 6600/440 V, (250 KVA ) requires ( 6%) of rated voltage to circulate (90%) of full load current at power factor (0.25) when the low voltage winding is short circuited and the no load loss is equal to (2500 W). Transformer B: 6600/420 V, (600 KVA) requires (9%) of rated voltage to circulate (80%) of full load current at power factor (0.16) when low voltage winding is short circuited and no load loss is equal to (4500 W). Calculate the followings: The terminal voltage when transformer A is supplying half load at power factor (0.6) lagging and transformer B is supplying (85%) of full load at power factor (0.85) leading.
Voltage control method connected across the load, to supply part of VAR required is ..... O Shunt capacitor O tap changing transformer O series capacitor O booster transformer
4. 100 kVA, 6800-240 V, 50 Hz single phase step down transformer has the following parameters: RLs=0.0082 RHs=2.62 Rfe-HS=50002 XLs=0.015N XHs=5.2N Xm.Hs=88002 Transformer is delivering 80% of rated load at rated voltage and 0.95 lagging power factor. Determine the following: a) The equivalent impedance of the transformer referred to primary. b) Input impedance of the combined transformer and load. c) Actual input voltage at HV side. d) Input impedance if load is disconnected. e) Exciting current at no load.
True or false 1-The power is transferred by induction and conduction in autotransformers 2-No load current in a transformer leads the voltage by about 70° - 80° 3-The efficiency of a two‑winding transformer for the same output compared to an autotransformer is smaller 4-The shell type of single phase transformer has single magnetic circuit 5-During short circuit test of a transformer, primary is supplied rated voltage
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4. A single-phase, 1000-kVA, 2400/8000-V, 60HZ distribution transformer has the following parameters: Resistance of the 2400-V winding: R1 = 2.75 2 Resistance of the 8000-V winding: R2 = 29.4 2 Leakage reactance of the 2400-V winding: X1= 1.8 Q Leakage reactance of the 8000-V winding: X2 = 20 2 Exciting admittance on the 2400-V side: 0.002 - j0.008 S %3| Draw the equivalent circuit referred to the high voltage side of the transformer. a. b. Draw the equivalent circuit referred to the low voltage side of the transformer. Show the numerical values of impedances on the equivalent circuits. 5. The transformer in Problem 4. is supplying a rated load of 1000-kVA at a rated secondary voltage of 8000 V and at 0.8 power factor lagging. Neglecting the transformer exciting current, determine the input terminal voltage of the transformer on the low-voltage side.
Figure 5 shows the core of a Linear Variable Differential Transformer (LVDT). S, S2 CORE Figure 5 Explain what happens when the core is at its maximum left, null and maximum right positions.