Problem + Hard 52-1    Source:   Problem 46 - List of Problems Circuits II - Discipline Electrical Circuits of the School of Engineering - UFRGS - 2017 - Prof. Dr. Valner Brusamarello.

In the circuit shown in Figure 52-01.1, knowing that the wattmeter reading is 7.5 kW, determine the value of E.

Problem + Hard 52-2    Source:   Adapted from Problem 39 - List of Problems Circuits II - Discipline Electric Circuits of School of Engineering - UFRGS - 2017 - Prof. Dr. Valner Brusamarello.

For the circuit shown in the Figura 52-02.1, it is known that wattmeter 1, W₁, has a reading equal to at 20 kW. Determine:

a)    The value of E

b)    The wattmeter 2 reading, W₂.

Problem + Hard 52-3    Source:   Adapted from Problem 3 of the 1st Exam of 2019 - Discipline Electric Circuits of Engineering School - PUCRS - 2019.

For the circuit shown in the Figura 52-03.1, it is known that:

That said, remembering the principle of conservation of complex power, calculate:

a) The total power factor of the loads.

b) The effective current consumed by the loads.

c) What reactive power must a capacitor bank connected in parallel generate to make the power factor of the unit circuit.

d) John, a cautious engineer designed this capacitor bank with twice the reactive power calculated in item previous. Explain the consequences of this error.

Problem + Hard 52-4    Source:   Adapted from Problem 3 of the 1st Exam of 2019 - Discipline Electric Circuits of Engineering School - PUCRS - 2019.

As a complement to the previous problem (see previous problem by clicking here!) determine:

a) The current I₁.

b) The values ​​of R_A , R_C and X_C .

c) A phasor diagram of the currents and voltages involved in the circuit.

Problem + Hard 52-5    Source:   Adapted from Problem 60 - List of Problems Circuits II - Electrical Circuits of the School of Engineering - UFRGS - 2017 - Prof. Dr. Valner Brusamarello.

The 20 kVA transformer, shown in Figure 52-05.1, operates with 62.5% of its nominal capacity and with FP = 0.8 overdue. The wattmeter W reads 4,000 W with the current lagging behind the voltage and the voltmeter V reads 200 V at your reading. Determine the values ​​of R, X and their nature.