List any four advantages and two disadvantages of 3 phase induction motor.

List any four advantages and two disadvantages of 3 phase induction motor.
by

1 Answer

Answer :

Advantages of 3 phase induction motor:

1) Simple in construction.

2) Economical in cost.

3) Requires very less maintenance.

4) High efficiency.

5) Low maintenace cost.

6) Self starting.

7) Robust and mechanically strong.

8) High overload capacity.

9) Small capacity motors, less than 5 HP, don't need a starter.

Disadvantages of 3 phase induction motor:

1) Essentialy a constant speed motor and its speed cannot be changed easily.

2) Medium starting torque.

3) Very sensitive to fluctuations in supply voltage.

4) Separate starter is required for stating for high capacity (more than 5HP) motors.

5) Cause of low system power factor, especially when motors are operated below its full load capacity.

6) It takes a large current from line at instant of starting.
by

Related questions

Explain how in a 3 phase induction motor to a rotating magnetic field is developed.

Description : Explain how in a 3 phase induction motor to a rotating magnetic field is developed. 

Last Answer : Production of Rotating Magnetic Field in Three-phase Induction Motor: In three-phase induction motor, the three-phase stator windings are displaced in space by 120° and their three-phase currents are displaced ... time by 120°. Such fluxes give rise to the resultant rotating magnetic field.

What are the advantages of the use of frequency converter instead of star-delta or soft starter?

Description : Can you guys explain the advantages of frequency converter against the star delta or soft starter?

Last Answer : ¬Soft starters  A soft starter is, as you would expect, a device which ensures a soft starting of a motor. A softstarter has different characteristics to the other starting ... at rated current from zero to full speed. Frequency converters are becoming cheaper all the time.

What type of motor is used for drilling machines?

Description : What type of motor is used for drilling machines?

Last Answer : universal motor also used in Handheld power tools, blowers, blenders, vacuum cleaners, polishers and kitchen appliances.universal motor is defined as a motor which may be operated either on direct or single phase AC supply at approximately the same speed and output

The speed control of universal motor used for sewing machines is by?

Last Answer : The speed control of universal motor used for sewing machines is by varying the resistance.

State any two applications of single phase autotransformer.

Description : State any two applications of single phase autotransformer.

Last Answer : Applications of single phase auto transformers: 1) Give small boost to distribution cable to correct the voltage drop. 2) As auto transformer starter for induction motors. 3) As furnace supply ... . 5) In control equipment for single phase locomotives. 6) As dimmer in lighting circuits.

State any two conditions for parallel operation of 3-phase transformer.

Description : State any two conditions for parallel operation of 3-phase transformer.

Last Answer : Conditions for Parallel operation of 3 phase transformer 1) Voltage ratings of both the transformers must be identical. 2) Percentage or p.u. impedance should be equal in magnitude. 3) X/R ratio ... between primary & secondary voltages must be same. 6) Phase sequence on both sides must be same.

State any four properties of Ideal transformer.

Description : State any four properties of Ideal transformer.

Last Answer : Properties of Ideal transformer: 1) No losses (iron and copper losses), hence no temperature rise. 2) No magnetic leakage i.e (Coefficient of coupling between primary and secondary windings is unity) 3) Zero winding ... drop i.e. E1 = V1, E2 = V2 5) Efficiency 100 %. 6) Regulation 0 %.

is induction motor ac or dc?

Last Answer : Induction motor is a AC motor it is also known as asynchronous motor .

The direction of rotation of an inverter fed 3-phase ac motor is reversed by

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

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

The inertia constants of two groups of machines which do not swing together are M1 and M2. The equivalent

Description : The inertia constants of two groups of machines which do not swing together are M1 and M2. The equivalent inertia constant of the system is

Last Answer : The inertia constants of two groups of machines which do not swing together are M1 and M2. The equivalent inertia constant of the system is M1M2/M1+M2

State any four advantages of A. C. over D. C .

Description : State any four advantages of A. C. over D. C . 

Last Answer : Advantages of AC over DC: i) It is possible to use a transformer. ii) Distribution efficiency is high. iii) Generation is easy and economical. iv) Construction of ac equipment/ machines is robust and simple ... . vii) AC system is economical than DC system. viii) AC system is safer than DC system.

Are we losing control over our life to machines?

Description : Are we losing control over our life to machines?

Last Answer : That is up to you. You can or you can decide to not.

Can anyone in the office machine business explain how click charges work?

Description : Can anyone in the office machine business explain how click charges work?

Last Answer : can you give more specifics? Typically the contract would include a certain amt. of impressions (clicks) then any after that would be at a lesser rate.

Heat Transfer Machines

Description : Heat Transfer Machines

Last Answer : Heat transfer machines are just the thing you need in order to do heat transfers on your clothing or whatever surface you want to decorate. In order for you to stick designs and precious stones on porous and ... is best. This will also give you an idea of what kind of designs you can choose from.

Compare core type transformer and shell type transformer on the following parameters. (i) Types of winding used, (ii) Application

Description : Compare core type transformer and shell type transformer on the following parameters. (i) Types of winding used, (ii) Application

Last Answer : Ans:

Define transformation ratio in terms of current and voltage.

Description : Define transformation ratio in terms of current and voltage.

Last Answer : (i) Transformation Ratio (K) is defined as the ratio of the primary current to the secondary current.  (ii) Transformation Ratio (K) is defined as the ratio of the secondary voltage to the primary voltage.

Define: (i) Commercial efficiency of a transformer and (ii) All day efficiency of a transformer.

Description : Define: (i) Commercial efficiency of a transformer and  (ii) All day efficiency of a transformer.

Last Answer : (i) Commercial Efficiency : It is the ratio of output power in watt to the input power in watt. (ii) All day efficiency of a transformer: It is the ratio of output energy in kWh to the input energy in kWh in the 24 hours of the day

A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.

Description : A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.

Last Answer : Iron loss is dependent on voltage and independent of load. Hence iron loss at 75% of Load = Iron loss at full load = 2 kW

Draw the connection diagram of long shunt differential D.C. compound generator.

Description : Draw the connection diagram of long shunt differential D.C. compound generator.

Last Answer : Ans:

In dc machines, the armature windings are placed on the rotor because of the necessity for

Description : In dc machines, the armature windings are placed on the rotor because of the necessity for  (1) electromechanical energy conversion (2) generation of voltage (3) commutation (4) development of torque

Last Answer : 3  Commutation

For protection of rotating machines against lightning surges _______ is used.

Description : For protection of rotating machines against lightning surges _______ is used.  (1) lightning arrester (2) capacitor (3) combination of lightning arrester and capacitor (4) lightning conductor and arrester

Last Answer : For protection of rotating machines against lightning surges combination of lightning arrester and capacitor is used. 

Laminated cores, in electrical machines, are used to reduce?

Description : Laminated cores, in electrical machines, are used to reduce?

Last Answer : Laminated cores, in electrical machines, are used to reduce eddy current loss.

Silicon steel is used in electrical machines because it has?

Description : Silicon steel is used in electrical machines because it has?

Last Answer : Silicon steel is used in electrical machines because it has low hysteresis loss.

Satisfactory commutation of D.C. machines requires?

Last Answer : Satisfactory commutation of D.C. machines requires brushes should be of proper grade and size, brushes should smoothly run in the holders, smooth, concentric commutator properly undercut.

For a D.C. machines laboratory following type of D.C. supply will be suitable?

Last Answer : For a D.C. machines laboratory following type of D.C. supply will be suitable induction motor D.C. generator set.

Brushes of D.C. machines are made of?

Last Answer : Brushes of D.C. machines are made of carbon.

Hopkinson's test on D.C. machines is conducted at?

Last Answer : Hopkinson's test on D.C. machines is conducted at full-load.

The purpose of retardation test on D.C. shunt machines is to find out?

Last Answer : The purpose of retardation test on D.C. shunt machines is to find out stray losses.

In D.C. machines the residual magnetism is of the order of?

Last Answer : In D.C. machines the residual magnetism is of the order of 2 to 3 percent.

In D.C. machines fractional pitch winding is used?

Last Answer : In D.C. machines fractional pitch winding is used to reduce the sparking.

Exciters of synchronous machines are?

Last Answer : Exciters of synchronous machines are d.c. shunt machines.

Losses which occur in rotating electric machines and do not occur in transformers are?

Description : Losses which occur in rotating electric machines and do not occur in transformers are?

Last Answer : Friction losses windage losses 

is efficiency of transformer is greater than electrical machine and why?

Last Answer : The efficiency of transformer is Greater than electrical Machine because there is no rotational losses in transformer and there is no air gap losses in transformer so losses is less in transformer compare to electrical machine so efficiency is higher in case of transformer.

The distributors for residential areas are (a) single phase (b) three-phase three wire (c) three-phase four wire (d) none of the above

Description : The distributors for residential areas are (a) single phase (b) three-phase three wire (c) three-phase four wire (d) none of the above

Last Answer : (c) three-phase four wire

State any four advantages of three phase induction motor.

Description : State any four advantages of three phase induction motor. 

Last Answer : Advantages of three phase induction motor https://youtu.be/27OIOCKN05U

In a D.C. 3-wire distributor using balancers and having unequal loads on the two sides (a) both balancers run as generators (b) both balancers run as motors (c) balancer connected to lightly- loaded side runs as a motor (d) balancer connected to heavily- loaded side runs as a motor

Description : In a D.C. 3-wire distributor using balancers and having unequal loads on the two sides (a) both balancers run as generators (b) both balancers run as motors (c) balancer connected to lightly- loaded side runs as a motor (d) balancer connected to heavily- loaded side runs as a motor

Last Answer : (c) balancer connected to lightly- loaded side runs as a motor

State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.

Description : State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.

Last Answer : Modifications are necessary in a dc series motor so that it operates satisfactorily on ac supply. The modifications are as follows:  1) AC series motor is built with a few field turns as ... and grinders 5) High speed vacuum cleaners 6) Sewing machines 7) Food processors 8) Drilling machine 

If a D.C. motor is connected across the A.C. supply it will?

Last Answer : If a D.C. motor is connected across the A.C. supply it will burn due to heat produced in the field winding by eddy currents.

A.C. series motor as compared to D.C. series motor has?

Last Answer : A.C. series motor as compared to D.C. series motor has smaller brush width, less number of field turns, more number of armature turns, less air gap.

If a D.C. series motor is operated on A.C. supply, it will?

Last Answer : If a D.C. series motor is operated on A.C. supply, it will spark excessively, have poor efficiency, have poor power factor.

In a A.C. series motor armature coils are usually connected to commutator?

Last Answer : In a A.C. series motor armature coils are usually connected to commutator through resistance.

In A.C. series motor compensating winding is employed to?

Last Answer : In A.C. series motor compensating winding is employed to reduce sparking at the brushes.

what is AC motor?

Description : AC motor

Last Answer : AC motor AC motor have two types one is Induction motor and second is synchronous motor. Induction motor have two types one is single phase induction motor and second is three phase ... self starting motor so using  external motor or we have to start it as induction motor.

A 3-phase 4 wire system is commonly used on (a) primary transmission (b) secondary transmission (c) primary distribution (d) secondary distribution

Description : A 3-phase 4 wire system is commonly used on (a) primary transmission (b) secondary transmission (c) primary distribution (d) secondary distribution

Last Answer : (d) secondary distribution

The spacing between phase conductors of a 220 kV line is approximately equal to (a) 2 m (b) 3.5 m (c) 6 m (d) 8.5 m

Description : The spacing between phase conductors of a 220 kV line is approximately equal to (a) 2 m (b) 3.5 m (c) 6 m (d) 8.5 m

Last Answer : (c) 6 m

The voltage of the single phase supply to residential consumers is (a) 110 V (b) 210 V (c) 230 V (d) 400 V

Description : The voltage of the single phase supply to residential consumers is (a) 110 V (b) 210 V (c) 230 V (d) 400 V

Last Answer : (c) 230 V

Define the terms related to a.c. supply with waveform : i) Instantaneous value ii) Time period iii) Amplitude iv) Phase difference.

Description : Define the terms related to a.c. supply with waveform : i) Instantaneous value ii) Time period iii) Amplitude iv) Phase difference. 

Last Answer : i) Instantaneous value: The instantaneous value is the value of an alternating quantity (it may ac voltage or ac current or ac power) at a particular instant of time in the cycle .  OR  ... difference: Phase difference is the difference in phase angle between two sinusoids or phasors. 

Total instantaneous power supplied by a 3-phase ac supply to a balanced R-L load is

Description : Total instantaneous power supplied by a 3-phase ac supply to a balanced R-L load is

Last Answer : Total instantaneous power supplied by a 3-phase ac supply to a balanced R-L load is constant

The stator of phase shifting transformer for use in conjunction with an A.C. potentiometer usually has a?

Last Answer : The stator of phase shifting transformer for use in conjunction with an A.C. potentiometer usually has a two-phase winding.

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

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

Last 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.