Recent activity in Electrical Circuits and Machines

A single phase transformer has a rating of $10 \mathrm{kVA}, 50 \mathrm{~Hz}, 1100 \mathrm{~V} / 220 \mathrm{~V}$. In an open circuit test with the high voltage side open...

In a series $R L$ circuit shown in the figure, the current through the resistor lags the AC source voltage by $45^{\circ}$. Let $R=100 \pi \Omega$ and $L=2 \mathrm{H}$.Th...

A single phase step-down transformer has a high voltage primary winding and a low voltage secondary winding. The secondary winding is connected to a load impedance $Z_{2}...

A three-phase squirrel-cage induction motor has a starting torque of $100 \%$ of the full load torque and a maximum torque of $300 \%$ of the full load torque. Neglecting...

A $50 \mathrm{~kVA}$ transformer has an efficiency of $95 \%$ at full load and unity power factor. Assume the core losses are negligible. The efficiency of the transforme...

In the figure shown, $\mathrm{R}=4.5 \mathrm{~k} \Omega, \Delta \mathrm{R}=1.5 \mathrm{~k} \Omega$, and $\mathrm{INA}$ is assumed to be ideal. The equivalent resistance b...

The switch in the following figure has been closed for a long time $(t<0)$. It is opened at $t=0$ seconds. The value of $d v_{0} / d t$ at $t=0^{+}$is $\_\_\_\_\_\_ ~ \ma...

The voltage applied and the current drawn by a circuit are$$ \begin{array}{c} v(t)=95+200 \cos (120 \pi t)+90 \cos \left(360 \pi t-60^{\circ}\right) \mathrm{V} \\i(t)=4 \...

For the circuit shown in the figure, the active power supplied by the source is ___________ $W$ (rounded off to one decimal place).

In the circuit shown, the switch is opened at $t=0 \mathrm{~s}$. The current $i(t)$ at $t=2 \mathrm{~ms}$ is __________ $\mathrm{mA}$ (rounded off to two decimal places).

In the circuit shown, the galvanometer $(G)$ has an internal resistance of $100 \: \Omega$. The galvanometer current $I_{G}$ is ____________ $\mu \mathrm{A}$ (rounded off...

The circuit given in the figure is driven by a voltage source $V_{S}=25 \sqrt{2} \angle 30^{\circ} \: \mathrm{V}$. The system is operating at a frequency of $50 \: \mathr...

A $2$-pole, $50 \mathrm{~Hz}, 3$-phase induction motor supplies power to a certain load at $2970 \: \mathrm{rpm}$ . The torque-speed curve of this machine follows a linea...

The bridge circuit, shown in Figure (a), can be equivalently represented using the circuit shown in Figure (b). The values of $R_{1}, R_{2}$, and $V_{\mathrm{C}}$ in the ...

Power consumed by a three-phase balanced load is measured using two-wattmeter method. The per-phase average power drawn by the load is $30 \: \mathrm{kW}$ at $\frac{\sqr...

Three parallel admittances $Y_{a}=-j 0.2 \mathrm{~S}, Y_{b}=0.3 \mathrm{~S}$, and $\quad Y_{c}=j 0.4 \mathrm{~S}$ connected in parallel with a voltage source $V_{s}=10 \a...

The circuit shown in Figure (a) can be represented using its equivalent T-model as shown in Figure (b). The values of the inductances $L_{1}, L_{2}$, and $L_{3}$ in the e...

A conducting semi-circular loop of radius $R=0.1 \; \text{m}, $ with its diameter centered at the origin, rotates in the $x-y$ plane about the origin with a constant angu...

A slip-ring induction motor is expected to be started by adding extra resistance in the rotor circuit. The benefit that is derived by adding extra resistance in the rotor...

A single-phase transformer has maximum efficiency of $98 \%$. The core losses are $\text{80 W}$ and the equivalent winding resistance as seen from the primary side is $0....

A household fan consumes $\text{60 W}$ and draws a current of $\text{0.3125 A (rms)}$ when connected to a $\text{230 V (rms) ac }$, $\text{50 Hz}$ single phase mains. The...

In the bridge circuit shown, the voltmeter $\text{V}$ showed zero when the value of the resistors are: $R_{1}=100\:\Omega$, $R_{2}=110\:\Omega$, and $R_{3}=90\:\Omega$. I...

The power in a $\text{400 V}$ ($\text{rms}$, line-line) three-phase, three-wire $\text{RYB}$ sequence system is measured using the two wattmetters, as shown. The $\text{R...

In the Figures (a) and (b) shown below, the transformers are identical and ideal ,except that the transformer in Figure (b) is centre -tapped. Asssuming ideal diodes, the...

In the circuit shown below, initially the switch S${_1}$ is open, then capacitor C1 has a charge of 6 coulomb, and the capacitor C2 has 0 coulomb. After s${_1}$ is closed...

Consider a circuit comprising only resistors with constant resistance and ideal independent DC voltage sources. If all the resistances are scaled down by a factor 10, an...

In the circuit shown below, maximum power is transferred to the load resistance R${_L}$, when R${_L}$ = $\_\_\_\_$ $\Omega$.

In the circuit shown below, a step input voltage of magnitude 5 V is applied at node A at time t = 0. If the capacitor has no charge for t $\leq$ 0, the voltage at node P...

In the circuit shown below, the angular frequency $\omega$ at which the current is in phase with the voltage is $\_\_\_\_\_\_$ rad/s.

In the figure, an RLC load supplied by a 230 V, 50 Hz single phase source. The magnitude of the reactive power (in VAr) supplied by the source is $\_\_\_\_\_$.

In the given circuit, superposition is applied.When V$_2$ is set to 0 V, the current I$_2$ is -6 A. When V$_1$ is set to 0 v, the current I$_1$ is + 6A. Current I$_3$ (in...

In the given circuit, the mesh currents $I{_1}$,$I{_2}$ and $I{_3}$ are $I{_1}$ = 1 A, $I{_2}$ =2 A and $I{_3}$ ...

A coil having an impedance of (10 + j100) $\Omega$ is connected in parallel to a variable capacitor as shown in figure. Keeping the excitation frequency unchanged, the va...

A series R-C circuit is excited by a 1 <0 V sinusoidal ac voltage source. The locus diagram of the phasor current L = (x + jy)A, when C is varied, while keeping R fixed, ...

The Thevenin equivalent circuit representation across terminals p – q of the circuit shown in the figure is a 1 V source in series...

In the circuit diagram, shown in the figure, $S_1$ was closed and $S_2$ was open for a very long time. At $t=0,\;S_1$ is opened and $S_2$ is closed. The voltage across th...

A series $R-L-C$ circuit is excited with an a.c. voltage source. The quality factor $(Q)$ of the circuit is given as $Q=30$. The amplitude of current in $\text{ampere}$ a...

In the a.c. bridge, shown in the figure, $R=10^3$ $\Omega$ and $C=10^{-7}$ $F$. If the bridge is balanced at a frequency $\omega_\circ$, the value of $\omega_\circ$ in ...

The current response of a series $\text R-L$ circuit to a unit step voltage is given in the table. The value of $L$ is __________$H$.

For the circuit, shown in the figure, the total real power delivered by the source to the loads is _____________$\text{kW}$.