# Drop in alternator frequency is corrected by:

14 views
Drop in alternator frequency is corrected by:

(1) Damper winding

(2) Increased prime mover output

(3) Automatic voltage regulator

(4) None of these

Drop in alternator frequency is corrected by: Increased prime mover output

## Related questions

In alternator where the voltage drop occurs?

In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50

A 8 pole alternator rotates at 750 r.p.m. Its frequency is

Is the speed of alternator is directly proportional to frequency?

If the excitation of an alternator operating in parallel with other alternators decreased, its: (1) Power factor becomes more leading (2) Output Kw will change (3) Power factor becomes more lagging (4) Power factor becomes unity

A field excitation of 20 A in a certain alternator results in an armature current of 400 A in short circuit and a terminal voltage of 2000 V on open circuit. The magnitude of the internal voltage drop within the machine at a load current of 200 A is  (A) 1 V (B) 10 V (C) 100 V (D) 1000 V

In an alternator at lagging power factor the generated voltage per phase as compared to that at unity power factor?

The magnitude of various voltage drops that occur in an alternator depends on?

When The dc converter in figure shown has a resistance load of R = 10 Ω and the input voltage is Vs 220 V the converter switch remains on, its voltage drop is Vo -2 V. The chopping frequency is fI K sW Vs If the duty cycle is 50%, determine: (a) the average output voltage V (b) the RMS output voltage Vo (c) the converter efficiency (d) the effective input resistance of the converter

The fall in speed of a dc generator due to increase in load can be corrected by  (1) cooling the armature.. (2) increasing the excitation. (3) reducing the load voltage. (4) increasing the input to the prime mover

The driving power from the prime-mover driving the alternator is lost but the alternator remains connected to the supply network; the field supply also remains on. The alternator will: A) get burnt B) behave as an induction motor but will rotate in the opposite direction C) behave as a synchronous motor and will rotate in the same direction D) behave as a synchronous motor but will rotate in a reverse direction to that corresponding to generator action

At which power factor alternator is said to be overexcited?

The economic size of a conductor in transmission and distribution lines of electric power is decided by (a) Ohm’s law (b) Kelvin’s law (c) Kirchhoff’s law(d) Faraday’s law

An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: A) 1000 rpm B) 920 rpm C) 950 rpm D) 970 rpm

Which alternator will have more number of poles ? (a) coupled to steam turbine (b) coupled to gas turbine (c) coupled to hydraulic turbine (d) None of the above

A 60 Hz, 2 pole alternator should run at • a. 3000 r.p.m. c. 1500 r.p.m. • b. 3600 r.p.m. d. 1800 r.p.m.

The power factor of an alternator depends on?

What is the frequency of an alternator which has 2 poles and makes 3600 revolutions per minute? A) 3600 HZ B) 60 Hz C) 120 Hz D) None of these

An alternator with frequency f1 is to be synchronized with an infinite bus of frequency f. For proper synchronization (1) f1=f (2) f1<f (3)f1>f (4) either (b) or (c)

The frequency (fr) of the rotor current in an induction motor is given by the expression (s = slip, f = supply frequency)

When 7/0.029 V.I.R cable is carrying 20 A, a drop of 1 V occurs every 12 m. The voltage drop in a 100 m run of this cable when it is carrying 10 A is nearly  (a) 4.2 V (b) 3.2 V (c) 1.2 V (d) 0.42 V

Which rotor is use for high speed in turbo alternators?

In d.c. choppers, for periodic time T, the output voltage can be controlled by frequency modulation by varying

In R-L-C series resonant circuit magnitude of resonance frequency can be changed by changing the value of?

A compensated wattmeter has its reading corrected for error due to (a) Frequency (b) Friction (c) Power consumed in current coil (d) Power consumed in pressure coil

The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open circuited. The rotor is made to rotate at a speed of 600 rpm in the opposite direction to the normal direction, The frequency of induced voltage across slip ring is A) 30 Hz B) 70 Hz C) 20 Hz D) 35 Hz

The reactance offered by a capacitor to an alternating current of frequency 50 Hz is 10 ohm. If frequency is increased to 100 Hz, the reactance will be (a) 2.5 ohm (b) 5.0 ohm (c) 20.0 ohm (d) 40.0 ohm

A rectangular waveguide is 5.1 cm by 2.4 cm (inside dimension). The cut off frequency of the dominant mode is

The speed of a 4-pole induction motor is controlled by varying the supply frequency while maintaining the ratio of supply voltage to supply frequency (V/f ) constant. At rated frequency of 50 Hz and rated voltage of 400 V its speed is 1440 rpm. Find the speed at 30 Hz, if the load torque is constant  (A) 882 rpm (B) 864 rpm (C) 840 rpm (D) 828 rpm

A rectangular waveguide is 4.2 cm by 1.85 cm. The cut-off frequency of the dominant mode through this waveguide is  (a) 3.57 GHz (b) 3.75 GHz (c) 3.70 MHz (d) 3.57 MHz

The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque  (1) Decreases (2) Increases (3) Remains constant (4) None of the above

A 4 GHz carrier is amplitude modulated by a low-pass signal of maximum cut off frequency 1 MHz. lf this signal is to be ideally sampled, the minimum sampling frequency should be nearly

Which is not measured by frequency meter ? (a) time period (c) phase are applied depend on amplitude of two (b) frequency (d) ratio of frequencies

The upper cut off frequency of a capacitive coupled RC amplifier is decided by  A) Input Coupling capacitance B) Transistor internal capacitances C) Output coupling capacitance D) Bypass capacitance

A 0.5 Hp, 6 pole wound rotor induction motor is excited by a 3 phase 60 Hz source. Calculate the frequency of the rotor current at standstill.  (A) 50 Hz (B) 30 Hz (C) 60 Hz (D) 120 Hz

The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes_____ohms.

What is meant by 3db frequency?

The number of electrical degrees ‘passed through’ in one revolution of a 6-pole synchronous alternator is: A) 360 degree B) 720 degree C) 1080 degree D) 2160 degree

The type of alternator used in hydroelectric power stations is

In wound rotor alternator, reactive power is maximum at a load angle of

In a 3 -phase alternator, if there is only magnetizing armature reaction, the load is :  (A) capacitive (B) inductive (C) resistive (D) inductive and resistive

Slip test is performed to determine :  (A) Slip in an induction motor  (B) Xd and Xq in a salient pole alternator  (C) Synchronous impedance in an alternator  (D) Positive and negative sequence impedances of an alternator

In a hydel power station, the number of poles of an alternator is 24. At what rpm the alternator must be driven to produce 50 Hz voltage?