Two wattmeter method is used for measurement of power in a balanced three-phase load supplied from a balanced three-phase system. If one of the wattmeters reads half of the other (both positive), then the power factor of the load is
A 0-1 Ampere moving iron ammeter has an internal resistance of $ 50\;m\Omega $ and inductance of 0.1 mH. A shunt coil is connected to extend its range to 0-10 Ampere for all operating frequencies. The time constant in milliseconds and resistance in $ m\Omega $ of the shunt coil respectively are
The slope and level detector circuit in a CRO has delay of 100 ns. The start-stop sweep generator has a response time of 50 ns. In order to display correctly, a delay line of
The following measurement are obtained on a single phase load; $\mathrm{V}=220\mathrm{V}\pm 1\%,\mathrm{I}=5.0\mathrm{A}\pm 1\%$ and $\mathrm{W}=555\mathrm{W}\pm 2\%$. If the power factor is calculated using these measurements, the worst case error in the calculated power factor in percent is__________. (Give the answer up to two decimal places)
The load shown in the figure is supplied by a 440 V (line-to-line), 3-phase source (RYB sequence). The load is balanced and inductive, drawing 3436 VA. When the switch S is in position N, the three watt-meters W_{1}, W_{2} and W_{3 }read 577.35 W each. If the switch is moved to position Y, the readings of the watt-meters in watt will be:
Two resistors with nominal resistance values R_{1} and R_{2} have addictive uncertainties $\triangle$R_{1} and $\triangle$R_{2}, respectively. When these resistances are connected in parallel, the deviation of the error in the equivalent resistance R is
A stationary closed Lissajous pattern on an oscilloscope has 3 horizontal tangencies and 2 vertical tangencies for a horizontal input with frequency 3 kHz. The frequency of the vertical input is
A 10 $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$ digit timer counter possesses a base clock of frequency 100 MHz. when measuring a particular input, the reading obtained is the same in: (i) Frequency mode of operation with a gating time of one second and (ii) Period mode of operation (in the x 10 ns scale). The frequency of the unknown input (reading obtained) in Hz is ____________.
When the Wheatstone bridge shown is used to find value of resistance ${R}_{\mathrm{X\; ,}}$the galvanometer G indicates zero current when ${R}_{1}=50$ \mathrm{\Omega}$$, ${R}_{2}=65$ \mathrm{\Omega}$$ and ${R}_{3}=100$ \mathrm{$ \mathrm{\Omega}$}$$. If ${R}_{3}$is known with $\pm 5\%$ tolerance on its nominal value of $100\mathrm\Omega$, what is the range of ${R}_{X}$ in Ohms?
A (0-50 A) moving coil ammeter has a voltage drop of 0.1 V across its terminals at full scale deflection. The external shunt resistance (in milliohms) needed to extend its range to (0-500 A) is ________.
An unbalanced DC Wheatstone bridge is shown in the figure. At what value of p will the magnitude of V_{0} be maximum?
Match the following:
A 3-phase balanced load which has a power factor of 0.707 is connected to balanced supply. The power consumed by the load is 5 kW. The power is measured by the two wattmeter method. The readings of the two wattmeters are
A capacitive voltage divider is used to measure the bus voltage ${V}_{bus}$ in a high-voltage 50 Hz AC system as shown in the figure. The measurement capacitor ${C}_{1}$ and ${C}_{2}$ have tolerances of $\pm 10$% on their normal capacitance values. If the bus voltage ${V}_{bus}$is 100 kV rms, the maximum rms output voltage ${V}_{\mathrm{out}}$(in kV), considering toleance , is _____________.
The coils of a wattmeter have resistances 0.01$\mathrm{\Omega}$ and 1000$\mathrm{\Omega}$; their inductances may be neglected. The wattmeter is connected as shown in the figure, to measure the power consumed by a load, which draws 25A at power factor 0.8. The voltage across the load terminals is 30V. The percentage error on the wattmeter reading is _________.
Power consumed by a balanced 3-phase, 3-wire load is measured by the two wattmeter method. The first wattmeter reads twice that of the second. Then the load impedance angle in radians is
In an oscilloscope screen, linear sweep is applied at the
The reading of the voltmeter (rms) in volts, for the circuit shown in the figure is __________
The dc current flowing in a circuit is measured by two ammeters, one PMMC and another electrodynamometer type, connected in series. The PMMC meter contains 100 turns in the coil, the flux density in the air gap is 0.2 Wb/m^{2}, and the area of the coil is 80 mm^{2}. The electrodynamometer ammeter has a change in mutual inductance with respect to deflection of 0.5 mH/deg. The spring constants of both the meters are equal. The value of current, at which the deflections of the two meters are same, is ________
The saw-tooth voltage waveform shown in the figure is fed to a moving iron voltmeter. Its reading would be close to _____________
While measuring power of a three-phase balanced load by the two-wattmeter method, the readings are 100 W and 250 W. The power factor of the load is _________.
Suppose that resistors R_{1} and R_{2} are connected in parallel to give an equivalent resistor R. If resistors R_{1} and R_{2} have tolerance of 1% each, the equivalent resistor R for resistors R_{1} =300 Ω and R_{2}= 200 Ω will have tolerance of
Two ammeters X and Y have resistances of 1.2 Ω and 1.5 Ω respectively and they give full-scale deflection with 150 mA and 250 mA respectively. The ranges have been extended by connecting shunts so as to give full scale deflection with 15 A. The ammeters along with shunts are connected in parallel and then placed in a circuit in which the total current flowing is 15A. The current in amperes indicated in ammeter X is __________.
An LPF wattmeter of power factor 0.2 is having three voltage settings 300 V, 150 V and 75 V, and two current settings 5 A and 10 A. The full scale reading is 150. If the wattmeter is used with 150 V voltage setting and 10 A current setting, the multiplying factor of the wattmeter is _________.
The two signals S1 and S2, shown in figure, are applied to Y and X deflection plates of an oscilloscope
The waveform displayed on the screen is
A periodic waveform observed across a load is represented by
$V\left(t\right)=\left\{\begin{array}{ll}1+\mathrm{sin}\omega t& 0\le \omega t<6\mathrm{\pi}\\ -1+\mathrm{sin}\omega t& 6\mathrm{\pi}\le \mathrm{\omega}\mathrm{t}<12\mathrm{\pi}\end{array}\right.$
The measured value, using moving iron voltmeter connected across the load, is
In the bridge circuit shown, the capacitors are loss free. At balance, the value of capacitance C1 in microfarad is _________.
The input impedance of the permanent magnet moving coil (PMMC) voltmeter is infinite. Assuming that the diode shown in the figure below is ideal, the reading of the voltmeter in Volts is
A strain gauge forms one arm of the bridge shown in the figure below and has a nominal resistance without any load as R_{s} = 300 $\mathrm{\Omega}$. Other bridge resistances are R_{1} = R_{2} = R_{3} = 300 $\mathrm{\Omega}$. The maximum permissible current through the strain gauge is 20 mA. During certain measurement when the bridge is excited by maximum permissible voltage and the strain gauge resistance is increased by 1% over the nominal value, the output voltage V_{0} in mV is
A periodic voltage waveform observed on an oscilloscope across a load is shown. A permanent magnet moving coil (PMMC) meter connected across the same load reads
The bridge method commonly used for finding mutual inductance is
For the circuit shown in the figure, the voltage and current expressions are
$v\left(t\right)={E}_{1}\mathrm{sin}\left(\omega t\right)+{E}_{3}\mathrm{sin}\left(3\omega t\right)$ and $i\left(t\right)={I}_{1}\mathrm{sin}\left(\omega t-{\Phi}_{1}\right)+{I}_{3}\mathrm{sin}\left(3\omega t-{\Phi}_{3}\right)+{I}_{5}\mathrm{sin}\left(5\omega t\right)$
The average power measured by the Wattmeter is
An analog voltmeter uses external multiplier settings. With a multiplier setting of 20 kΩ, it reads 440 V and with a multiplier setting of 80 kΩ, it reads 352 V. For a multiplier setting of 40 kΩ, the voltmeter reads
Consider the following statement (i) The compensating coil of a low power factor wattmeter compensates the effect of the impedance of the current coil. (ii) The compensating coil of a low power factor wattmeter compensates the effect of the impedance of the voltage coil circuit.
The bridge circuit shown in the figure below is used for the measurement of an unknown element Z_{X}. The bridge circuit is best suited when Z_{X} is a
A dual trace oscilloscope is set to operate in the ALTernate mode. The control input of the multiplexer used in the y-circuit is fed with a signal having a frequency equal to
A $4\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$ digit DMM has the error specification as: 0.2% of reading + 10 counts. If a dc voltage of 100 V is read on its 200 V full scale, the maximum error that can be expected in the reading is
A wattmeter is connected as shown in the figure. The wattmeter reads
An ammeter has a current range of 0 - 5 A, and its internal resistance is 0.2Ω. In order to change the range to 0 - 25 A, we need to add a resistance of
The Maxwell's bridge shown in the figure is at balance. The parameters of the inductive coil are
The pressure coil of a dynamometer type wattmeter is
The two inputs of a CRO are fed with two stationary periodic signals. In the X-Y mode, the screen shows a figure which changes from ellipse to circle and back to ellipse with its major axis changing orientation slowly and repeatedly. The following inference can be made from this.
The figure shows a three-phase delta connected load supplied from a 400V, 50 Hz, 3-phase balanced source. The pressure coil (PC) and current coil (CC) of a wattmeter are connected to the load as shown, with the coil polarities suitably selected to ensure a positive deflection. The wattmeter reading will be
An average-reading digital multimeter reads 10V when fed with a triangular wave, symmetric about the time-axis. For the same input an rms-reading meter will read.
Two 8-bit ADCs, one of single slope integrating type and other of successive approximation type, take T_{A} and T_{B} times to convert 5 V analog input signal to equivalent digital output. If the input analog signal is reduced to 2.5 V, the approximate time taken by the two ADCs will respectively, be
Two sinusoidal signals p(ω_{1}t) = A sinω_{1}t and q(ω_{2}t) are applied to X and Y inputs of a dual channel CRO. The Lissajous figure displayed on the screen shown below :
The signal q(ω_{2}t) will be represented as
The ac bridge shown in the figure is used to measure the impedance Z .
If the bridge is balanced for oscillator frequency f = 2 kHz, then the impedance Z will be
The probes of a non-isolated, two channel oscillocope are clipped to points A, B and C in the circuit of the adjacent figure. V_{in} is a square wave of a suitable low frequency. The display on Ch_{1} and Ch_{2} are as shown on the right. Then the “Signal” and “Ground” probes S_{1}, G_{1} and S_{2}, G_{2} of Ch_{1} and Ch_{2} respectively are connected to points: