Measurements

The maximum percentage error in the equivalent resistance of two parallel connected resistors of $100 \Omega$ and $900 \Omega$ with each having a maximum $5 \%$ error is ____________\%. (Round off to nearest integer valu...

The table lists two instrument transformers and their features: Instrument Transformers Features X) Current Transformer (CT) P) Primary is connected in parallel to the grid Y) Potential Transformer (PT) Q) Open circuited...

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 following measurements are obtained on a single phase load: $$V = 220 V$$ $$ \pm $$$$1$$%. $${\rm I}$$$$= 5.0$$ $$A$$ $$ \pm \,1$$% and $$W=555$$ $$W$$ $$ \pm \,2$$%. If the power factor is calculated using these mea...

Two resistors with nominal resistance values $${R_1}$$ and $${R_2}$$ have additive uncertainties $$\Delta {R_1}$$ and $$\Delta {R_2},$$ respectively. When these resistances are connected in parallel, the standard deviati...

A $$10{\raise0.5ex\hbox{$\scriptstyle 1$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 2$}}$$ digit timer counter possesses a base clock of frequency $$100$$ $$MHz$$. When measuring a particular input, the re...

A 3-phase balanced load which has a power factor of 0.707 is connected to a 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 a...

An $$LPF$$ wattmeter of power factor $$0.2$$ is having three voltage settings $$300V,$$ $$150V$$ and $$75V,$$ and two current settings $$5 A$$ and $$10A.$$ The full scale reading is $$150.$$ If the wattmeter is used with...

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 ___________.

Two ammeters $$X$$ and $$Y$$ have resistances of $$1.2$$ $$\Omega $$ and $$1.5$$ $$\Omega $$ respectively and they give full-scale deflection with $$150$$ $$mA$$ and $$250$$ $$mA$$ respectively. The ranges have been exte...

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

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 r...

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 compensa...

A $$4\,{1 \over 2}$$ 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 expressed in t...

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 $$8$$ $$A$$ $$D$$ $$C$$ $$s$$ one of single slope integrating type and other of successive approximation type. Take $${T_A}$$ and $${T_B}$$ times to connect $$5V$$ analog input signal to equivalent digital output. If...

A variable $$'w'$$ is related to three other variables $$x, y, z$$ as $$w=xy/z.$$ The variables are measured with meters of accuracy$$ \pm $$ $$0.5$$% reading, $$ \pm 1\% $$ of full scale value and $$ \pm 1.5\% $$ readin...

An energy meter connected to an immersion heater (resistive) operating on an $$AC$$ $$230V,$$ $$50$$ $$Hz,$$ $$AC$$ single phase source reads $$2.3$$ units ($$kWh$$) in $$1$$ hour. The heater is removed from the supply a...

A $$200/1$$ current transformer $$(CT)$$ is wound with $$200$$ turns on the secondary on a toroidal core. When it carries a current of $$160$$ $$A$$ on the primary, the ratio and phase errors of the $$CT$$ are found to b...

A digital-to-analog converter with a full scale output voltage of $$3.5V$$ has resolution close to $$14mV.$$ It's bit size is _____.

Two wattmeter's, which are connected to measure the total power on a three-phase system supplying a balanced load, read $$10.5$$ $$kW$$ and $$–2.5$$ $$kW$$ respectively. The total power and the power factor respectively...

A $$50$$ $$Hz,$$ bar primary $$CT$$ has a secondary with $$500$$ turns. The secondary supplies $$5A$$ current into a purely resistive burden of $$1\,\Omega $$. The magnetizing ampere-turns is $$200$$. The phase angle bet...

The core flux in the $$CT$$ of above problem under the given operating condition is

A dc A-h meter is rated for 15 A, 250V. The meter constant is 14.4 A-sec/rev. The meter constant at rated voltage may be expressed as

A $$500$$ $$A/5$$ $$A,$$ $$50$$ $$Hz$$ current transformer has a bar primary. The secondary burden is a pure resistance of $$1\,\Omega $$ and it draws a current of $$5A$$. If the magnetic core requires $$250$$ AT for mag...

The voltage-flux adjustment of a certain $$1$$-phase $$220$$ $$V$$ induction watt-hour meter is altered so that the phase angle between the applied voltage and the flux due to it $${85^0}$$ (instead of $${90^0}$$). The e...

A wattmeter reads $$400$$ $$W$$ when its current coil is connected in the $$R$$ phase and its pressure coil is connected between this phase and the neutral of a symmetrical $$3$$-phase system supplying a balanced star co...

The minimum number of wattmeter(s) required to measure 3 $$-$$ phase, 3 $$-$$ wire balanced or unbalanced power is

Resistances $${R_1}$$ and $${R_2}$$ have, respectively, nominal values of $$10\Omega $$ and $$5\Omega ,$$ and tolerances of $$ \pm 5\% $$ and $$ \pm 10\% $$. The range of values for the parallel combination of $${R_1}$$...

The two wattmeter method is used to measure active power on a three phase, three wire system. If the phase voltage is unbalanced, then the power reading is

A $$3$$ - $$\phi $$ load operates with balanced voltages applied to its terminals, and draws balanced currents. The potential coil of a moving coil wattmeter is connected from $$R$$ to $$Y$$ terminals of the load. The cu...

Instrument transformers are known to introduce magnitude and phase errors in measurements. These are primarily due to

For a dual $$ADC$$ type $$3\,{\raise0.5ex\hbox{$\scriptstyle 1$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 2$}}$$ digit $$DVM$$, the reference voltage is $$100$$ $$mV$$ and the first integration time is se...

Electro dynamic type watt meters have large errors while measuring power in a.c circuits at low power factor conditions, since the voltage across and the current though the

For a dual $$ADC$$ type $$3\,\,{1 \over 2}$$ digit $$DVM$$, the reference voltage is $$100mV$$ and the first integration time is set to $$300$$$$ms$$. For some input voltage, the ''deintegration'' period is $$370.2ms$$....

A d.c. voltmeter has a sensitivity of $$1000$$$$\Omega /volt.$$ When it measures half full scale in $$100$$ $$V$$ range, the current through the voltmeter is

The primary current in a current transformer is dictated by

Fringing in capacitive type transducer can be minimized by providing a _________

A $$3{1 \over 2}\,$$ digit, $$2$$ $$V$$ full scale slope $$ADC$$ has its integration time set to $$300$$ $$ms.$$ If the input to the $$ADC$$ is ($$1$$+$$1sin$$ $$314$$ $$t$$) V, then the ADC output will be

A precise measurement guarantees accuracy of the measured quantity.

A d.c. potentiometer is designed to measure up to about $$2$$ $$V$$ with a slide wire of $$800$$ mm. A standard cell of emf $$1.18V$$ obtains balance at $$600$$ mm. A test cell is seen to obtain balance at $$680$$ mm. Th...

A metal strain gauge has gauge factor of two, it's nominal resistance is $$120$$ Ohms. It is undergoes a strain of $${10^{ - 5}},$$ the value of change of resistance in response to the strain is

V RN , V YN and V BN are the instantaneous line to neutral voltages and i R , i Y and i B are instantaneous line currents in a balanced three-phase circuit, the computation, V RN (i y $$-$$ i B ) $$-$$ (V YN $$-$$ V BN )...

In a dual slope integrating type digital voltmeter the first integration is carried out for $$10$$ periods of the supply frequency of $$50Hz.$$ If the reference voltage used is $$2V,$$ the total conversion time for an in...

In $$d.c.$$ potentiometer measurements, a second reading is often taken after reversing the polarities of the $$s.c.$$ supply and the unknown voltage, and the average of the two readings is taken. This is, with a view to...

A resistance is measured by the voltmeter- ammeter method employing d.c. excitation and a voltmeter of very high resistance connected directly across the unknown resistance. If the voltmeter and ammeter readings are subj...