Every AC supply is not ideal AC it contains DC component so to provide restriction to DC component in supply we have to use Capacitor

answered
Jan 21, 2018
by
NITIN P. DESHMUKH

**Description** :

Power factor of an inductive circuit is usually improved by connecting capacitor to it in?

**Answer** : Power factor of an inductive circuit is usually improved by connecting capacitor to it in parallel.

**Description** : What is the role of a capacitor in a circuit?

**Description** : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be
(1) unaffected (2) decreased (3) increased (4) either decreased or increased depending on the direction of the DC field

**Answer** : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be either decreased or increased depending on the direction of the DC field

**Description** : An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V

**Answer** : An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V

**Description** : For a DC circuit capacitor is

**Answer** : For a DC circuit capacitor is virtually an open circuit

**Description** : Explain working of static AC circuit breaker.

**Answer** : Static AC Circuit breaker: The circuit configuration of static AC circuit breaker using SCR is shown in the figure. When switch S' is closed, the SCRs T1 and T2 are fired in positive ... non-availability of gate current. Thus the maximum time delay for breaking the circuit is one half-cycle.

**Description** : Explain working of AC circuit breaker using SCR with circuit diagram.

**Answer** : AC Circuit Breaker: The circuit configuration of static AC circuit breaker using SCR is shown in the figure. When switch S' is closed, the SCRs T1 and T2 are fired in positive ... to non-availability of gate current. Thus the maximum time delay for breaking the circuit is one half-cycle.

**Description** : Can we apply the superposition theorem to AC circuit?

**Description** : In an A.C. circuit power is dissipated in?

**Answer** : In an A.C. circuit power is dissipated in resistance only.

**Description** : The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is?

**Answer** : The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is 6 kVAR.

**Description** :

The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is?

**Answer** : The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is 32 kW.

**Description** : How does a capacitor improve power factor?

**Answer** : Every circuit are usually more inductive than capacitive.it means that the current lags by voltage at small angle.hence we have to compensate this situation so we use Capacitor then this lag is compensate ... angle becomes low and the value of cos(phase angle) is increase and hence power also max.

**Description** : Thyristor Switched Capacitor (TSC)

**Answer** : Thyristor Switched Capacitor (TSC) TSC is a static compensator. TSC is use for compensating reactive power. Compensation is required for voltage regulation, increasing stability, ... compensating device like TCS phase angle between voltage and current can be maintain.

**Description** : In any A.C. circuit always?

**Answer** : In any A.C. circuit always apparent power is more than actual power.

**Description** : All the rules and laws of D.C. circuit also apply to A.C. circuit containing?

**Answer** : All the rules and laws of D.C. circuit also apply to A.C. circuit containing resistance only.

**Description** : what is TCSC?

**Answer** : Thyristor Controlled Series Capacitor (TCSC)

**Description** : A large AC generator, supplying power to an infinite bus, has a sudden short-circuit occurring at its terminals. Assuming the prime mover input and the voltage behind the transient reactance to remain constant immediately after the fault, acceleration of the generator rotor is

**Answer** : A large AC generator, supplying power to an infinite bus, has a sudden short-circuit occurring at its terminals. Assuming the prime mover input and the voltage behind the transient reactance ... , acceleration of the generator rotor is inversely proportional to the moment of inertia of the machine

**Description** : What happens to the capacitance if mica is inserted between the plates of an air capacitor?
A) The capacitance increases B) The capacitance decreases
C) The capacitance remains the same D) The capacitance becomes zero

**Answer** : What happens to the capacitance if mica is inserted between the plates of an air capacitor? A) The capacitance increases B) The capacitance decreases C) The capacitance remains the same D) The capacitance becomes zero

**Description** : In an ac series RLC circuit, the voltage across R and L is 20 V; voltage across L and C is 9 V and voltage across RLC is 15 V. What is the voltage across C?

**Answer** : In an ac series RLC circuit, the voltage across R and L is 20 V; voltage across L and C is 9 V and voltage across RLC is 15 V. What is the voltage across C? 7 V

**Description** : Explain the principle of ON-OFF control and phase control of AC voltage controller with suitable circuit and waveforms.

**Answer** : The integral cycle control (on-off control) and phase angle control are the two types of AC voltage controller. The principle of ON-OFF control: The on-off control is also called an integral cycle ... control. In phase control, the switch is on for some period of each cycle.

**Description** : What is the difference between an AC and DC generator?

**Answer** : The generator which generates DC voltage is called DC generator and generator which generates AC voltage is called AC generator (or) Alternator. In DC generator armature is rotated and field winding ... generator. A DC generator can generate low voltages but an AC generator can generate upto 11kv.

**Description** : What is the direction of an AC current?

**Answer** : The magnitude and direction of alternating current is changes with respect to time. So for half cycle it is positive and for next half cycle it is negative.

**Description** : What is a capacitor voltage transformer?
A) It is a transformer used in power systems to step up low voltage signals and provide extra high voltage
B) It is a transformer used in power systems to step up high voltage signals and provide extra high voltage
C) It is a transformer used in power systems to step down extra high voltage signals and provide low voltage
D) None of these

**Answer** : What is a capacitor voltage transformer? A) It is a transformer used in power systems to step up low voltage signals and provide extra high voltage B) It is a transformer used in power systems ... power systems to step down extra high voltage signals and provide low voltage D) None of these

**Description** : What is the charge on each capacitor when a 150 V is applied across two capacitors with values 5 μF and 10 μF, connected in series?
A) 500 μC B) 0.5 μC
C) 0.5 C D) None of these

**Answer** : What is the charge on each capacitor when a 150 V is applied across two capacitors with values 5 μF and 10 μF, connected in series? A) 500 μC B) 0.5 μC C) 0.5 C D) None of these

**Description** : What is the stored energy when 200 V is applied across a 7 μF capacitor?
A) 1400 Joules B) 0.7 Joules
C) 0.14 Joules D) None of these

**Answer** : What is the stored energy when 200 V is applied across a 7 μF capacitor? A) 1400 Joules B) 0.7 Joules C) 0.14 Joules D) None of these

**Description** : What are the characteristics of a capacitor?

**Description** : What is the basic use of capacitor?

**Description** : What is the basic function of a capacitor?

**Description** : What is the symbol of a capacitor?

**Answer** : symbol of a capacitor

**Description** : what is the difference between capacitor and battery ?

**Answer** : A capacitor stores power but in very small quantitys and work in D/C and A/C circuits and it needs a power source from wich it gets the power it stores and a battery also stores power but in much larger quantitys measured in Amp/Hours

**Description** : Is the power line voltage available in our homes a dc or an ac voltage?

**Answer** : The power line voltage available in our homes is AC. Mobile dwellings are the most commonly DC-supplied homes and even then they tend to include AC supply for heavier loads.

**Description** : In an adjustable speed ac drive which quantity gets reduced above rated speed ?
(A) developed torque (B) stator frequency
(C) reduced starting torque (D) stator current

**Answer** : In an adjustable speed ac drive which quantity gets reduced above rated speed ? (A) developed torque (B) stator frequency (C) reduced starting torque (D) stator current

**Description** : Define : i) Average value ii) RMS value of an AC Wave.

**Answer** : i) Average value: The average value is defined as the average of all instantaneous values during one alternation . That is, the ratio of the sum of all considered instantaneous values to the ... as produced by the alternating current when flowing through the same resistance for the same time.

**Description** : An ac voltmeter using full -wave rectification and having a sinusoidal input has an ac sensitivity equal to
(1) 1.414 times dc sensitivity (2) dc sensitivity (3) 0.9 times dc sensitivity (4) 0.707 times dc sensitivity

**Answer** : An ac voltmeter using full -wave rectification and having a sinusoidal input has an ac sensitivity equal to 0.9 times dc sensitivity

**Description** : The direction of rotation of an inverter fed 3-phase ac motor is reversed by
(A) a mechanical reversing switch (B) reversing the input dc link voltage
(C) operating the inverter as a rectifier (D) changing the sequence of switching

**Answer** : The direction of rotation of an inverter fed 3-phase ac motor is reversed by changing the sequence of switching

**Description** : Why does a transformer only work with an AC supply?

**Answer** : The transformer work depends on the induction as main principle ,for that AC is the right means

**Description** : Why is a capacitor used in a single phase motor and not in three phase motor ?

**Answer** : In 1-phase induction motor capacitor work is generate the auxiliary winding current than excite the main winding to rotor starts rotate. After rotor start rotating about 75% of their speed than auxiliary ... emf to start the motor.so,in 3-phase induction motor is self start induction motor.

**Description** : Why is a capacitor used in a ceiling fan ?

**Answer** : For splitting phase so that a rotating magnetic field will be produced & as per Lenz's law a torque will be created & rotor starts rotating. In single phase if capacitor is not used for split phase then a pulsating mag. field is produced which is unable to produce torque on rotor

**Description** : Dielectric loss in a capacitor is best measured by
(A) Wien Bridge
(B) Schering Bridge
(C) Anderson Bridge
(D) Heaviside-Campbell Equal Ratio Bridge

**Answer** : Dielectric loss in a capacitor is best measured by Schering Bridge

**Description** :

**Answer** : The capacitors used in single-phase capacitor motors have no polarity marking.

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