AC CIRCUIT POWERLINE SUPPLY

59問 • 2年前

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A 10 ohms resistor is connected in parallel to Z=3+j4 ohms. What is the power factor?

0.809

Two impedance, Z=0.8+j5.6 and Z2 = 8-j16 and a single phase motor are connected in parallel across 200 Vrms, 60 Hz supply. The motor draws 5kVa at 80% power fsctor lagging Find the overall factor.

0.6 lagging

* A coil of wire having a value of 10 + j16 ohm is connected inseries with a capacitance reactance Xc, and this series combination is then connected in parallel with resistor R. if the equivalent impedance of the current circuit is 8+j0 ohm, what is the value of R in ohm?

A source of 100 volts rms is supplying a resistsnce 80 ohms parallel with a 200 mH inductor To what angle is the current lag or lead?

43.3 deg lag

Two impedance Z1=2+j4 and Z2=R+j0 are connected in parallel. Determine R so that the pf of the circuit is 0.9 lagging

3.2 ohms

A factory has an average demand of 150 kW at 70.7% power factor. What is the minimum size of capsvitor required to raise the power factor tp 95%?

101 kvar

A single phase induction motor is rated 5hp, 75% power factir and 220 volts What approximate size of capacitor is nessary to raise the power factor to about 95%

3 kvar

in a series resonant circuit, the impedance of the circuit is

minimum

What capacitance must be placed in series with an inductance of 0.05 H so that at 100 Hz. the impedance becomes equal to the ohmic resitance?

50 uF

An 8 ohm resistance, 16 ohm reactance and an unkwon capacitor are connected in series across a 100 V, 50 Hz supply. The current drawn by the circuit is 12.5 A. The value of capacitance of the capacitor in micro faraf will be

200

A coil of 40 resistance has an inductance of 100 mH and id connected in parallel with 40 uF capacitor. What id the resosnance frequency of the circuit?

47.75 Hz

What is the bandwidth of a series resonant circuit with 8 ohm resistance , 40 mH inductance and 0.25 micro farad capacitance

200 rad/sec

To a series RLC circuita voltage of 10 V is applied. If Q of the coil at resonant frequency is 20 the voltage across the inductor at resonant frequency will be.

200V

What is the Q factor of a series resonant circuit consisting of 2.4 ohm residtsnce snd 30 micro farad capacitance. Take 1000 rad/sec angular freuquency.

13.9

The ratio of the bandwidth to the resonance frequency is called the________ of the circuit

selectivity

An RLC series circuit consist of a resistance of 1000 ohms an inductance of 100 mH and a capacitance of 10 uF. If the voltage of 100 voltage of 100 volts is applied across the combination, find the upper half power frequency

159.8 kHz

A coil of 40 ohms resistance has an induction of 100 mH is connected in parallel with a 30 uF capacitor. What is the resonance frequency of the circuit?

66.3 Hz

A 5:1 ideal transformer is used to couple a load to a generatir whise internsl impedance is 2500+j2500 ohms. Determine the load impedance that will transfer maximum power

100-j100

The period of a wave

time required to complete one cycle

A sine wave has a frequency of 50 Hz. Its angular frequency is

100π

For a frequency of 200 Hz, the time period will be

0.0005 s

An AC current is given by I=200 sin 100mt. It will achieve a value of 100 A after second

1/900

The rms value of a sine wave is 100 A. Its peak value is

141.4 A

**What is the rms value of an AC current?

The steady current that will charge a battery at the same rate as the actual current

The voltage of domestic supply is 220 V. This figure represents

rms value

For a sinusoidal wave of maximum value 30 amperes, what is the average value over half cycle

19.09 A

In the case of an unsymmetrical alternating current the average value must always be taken over

the whole cycle

The rms value and mean value is the same in the case of

square wave

An AC voltage of 50 Hz has maximum value of 50 V. Its value after 1/800 second after the instant the current is zero, will be

25 V

A sine wave of voltage varies from zero to maximum of 200 V. How much is the voltage at the instant of 30° of the cycle?

100 V

The rms value of a half-wave rectified current is 100 A. Its value for full-wave rectification would be_______amperes

141.4

For the same peak value which of the following wave will have the highest rms value?

square wave

The instantaneous voltage and current equations of an ac circuit are v(t)=8 sin 3t volts and i(t)=2 sin 3t ampere respectively What is the instantaneous form of power?

p(t)=16 sin^2 3t

The instantaneous voltage equation is represented by v(t)=169 7 cos(377t-150°) Its rectangular complex expression

60-j103.9 volts

What will be the phase angle between two alternating waves of equal frequency, when one wave attains maximum value the other is at zero value?

90°

What is the ms value of complex current having fundamental, de component 3 harmonic and fifth harmonic ms component of 10A, 5A 3A and 1.5A respectively

11.67 A

In a pure resistive circuit

current is in phase with the voltage

*Power factor of electric bulb is

unity

*In a purely inductive circuit, the current lags the voltage by _______

one fourth of the cycle

In a purely inductive circuit

actual power is zero

In a pure inductive circuit if the supply frequency is reduced to 1/2 the current will

be doubled

A pure inductance connected across 250 V, 50 Hz supply consumes 100 W. This consumption

the statement given is false

Which of the following circuit component opposes the change in the circuit voltage?

capacitance

The reactance offered by a capacitor to altemating current of frequency 50 Hz is 200. If the frequency is increased to 100 Hz, reactance becomes

10 ohms

***A capacitor of 100 KVAR, 400V and 50 Hz. What is the capacitor rating at 60 Hz 230V in KVAR?

Which of the following AC device is used to measure the angle between the voltage and its current

phase angle meter

The ratio of active power to apparent power is known as______ factor

power

All definition of power factor of a series R-L-C circuit are correct except

ratio of net reactance and impedance

In an AC circuit, a low value of KVAR compared with kW indicates

high power factor

The input of an AC circuit having power factor of 0.8 lagging is 40 KVA. The power drawn by the circuit is A 12 KW

32 kW

A washing machine is, in effect, an R-L. circuit. If the machine takes 311 W and 4.5 A from a 115- V source when operating normally Find its power factor

0.60 lagging

The apparent power drawn by an AC circuit is 10 KVA and active power is 8 kW. The reactive power in the circuit is

6 kVAR

A circuit draws ims current of I=5-j4 amperes from a source voltage of Vrms=150+j180 volts What is the complex power expression of the circuit?

30-j1500 VA

**A coil draws 0.5 from a 120 V, 60 Hz source at 70% lagging power factor, what are the coil resistance in ohms and inductance in H?

R=171 and L= 0.554

**In a series RC circuit, the voltage across the capacitor and the resistor are 60V and 80 V respectively. What is the total voltage of the circuit

100 V

In a circuit containing R, L and C, power loss can take place in

R only

In aR-L-C circuit the impedance is given by

Z = √R^2 + (XL-XC)^2

An alternating voltage V=160+;120~V applied to a circuit and the subsequent current flowing I=-6+j15A The impedance of the circuit is

3.2-j12

A resistance R and inductive reactance X are connected in series across 2.4 kV rms absorbs 288 KW at 0.8 power factor. Find the value of R & X in ohms

12.8 & 9.6

DC CIRCUITS POWERLINE

premopremo remo · 12回閲覧 · 75問 · 2年前

DC CIRCUITS POWERLINE