Explain DOL starter used for 3 phase induction motor.

Explain DOL starter used for 3 phase induction motor.
by

1 Answer

Answer :

DOL Starter Used for 3 Phase Induction Motor:

image

The direct online starter consist of overload relay (OLC), contactor, start-push button S1 (normally open), stop-push button S2 (normally closed), magnetizing coil C, Remote stop button S3 (normally closed), main contacts M, hold on contact A as shown in above figure. For staring the motor, the start-push button is pressed. The contactor coil C gets connected across line voltage & ultimately it gets magnetized. It pulls the plunger towards left making contacts of M and A which provides power supply to induction motor and motor starts. For stopping the motor after work the stop-push / remote button is pressed which disconnects supply to coil C so it releases the plunger and cuts off the supply of motor and motor stops. The overload coil (OLC) protects the motor against overload and short circuit by opening the contact D.

by

Related questions

Draw the power and control circuit diagram for forward — stop — Reverse type DOL starter for 3 phase induction motor.

Description : Draw the power and control circuit diagram for forward — stop — Reverse type DOL starter for 3 phase induction motor.

Last Answer : Draw the power and control circuit diagram for forward — stop — Reverse type DOL starter for 3 phase induction motor.

A 3-phase delta connected squirrel cage induction motor when started with a DOL starter has a starting

Description : A 3-phase delta connected squirrel cage induction motor when started with a DOL starter has a starting torque of 600 NM. Its starting torque when star delta starter is used:

Last Answer : A 3-phase delta connected squirrel cage induction motor when started with a DOL starter has a starting torque of 600 NM. Its starting torque when star delta starter is used: 200 NM

Draw and explain star delta starter for 3 phase induction motor

Description : Draw and explain star delta starter for 3 phase induction motor

Last Answer : Star Delta Starter for 3 Phase Induction Motor:  Diagram Explanation: The stator winding of the motor which is designed for delta operation is connected in star during starting ... which connects stator windings in delta connection. Now each stator phase gets full line voltage VL.

A three-phase cage induction motor is started by direct-on-line (DOL) switching at the rated voltage. If the

Description : A three-phase cage induction motor is started by direct-on-line (DOL) switching at the rated voltage. If the starting current drawn is 6 times the full load current, and the full load slip is 4%, then ratio of the ... load torque is approximately equal to (A) 0.24 (B) 1.44 (C) 2.40 (D) 6.00

Last Answer : A three-phase cage induction motor is started by direct-on-line (DOL) switching at the rated voltage. If the starting current drawn is 6 times the full load current, and the full load slip is 4%, then ratio of the starting developed torque to the full load torque is approximately equal to 1.44

Explain speed control method of 3 phase induction motor by the following methods: (1) Pole changing (2) Rotor resistance control (3) Stator voltage

Description : Explain speed control method of 3 phase induction motor by the following methods: (1) Pole changing (2) Rotor resistance control (3) Stator voltage

Last Answer : 1) Pole Changing Method:  Synchronous speed is given by, From the above equation of synchronous speed, it can be seen that synchronous speed (and hence, running speed) can ... in voltage and consequently the speed decreases and vice versa. Ultimately speed depends on the supply voltage.

Explain the construction of three phase induction motor with neat diagram.

Description : Explain the construction of three phase induction motor with neat diagram.

Last Answer : Construction of Three-phase Induction Motor: There are two main parts of the three phase induction motor:  i) Stator which is the stationary part  ii) Rotor which is the rotating ... slip-rings. In this rotor also the slots are not exactly parallel to the shaft but slightly skewed.

State any four applications of 3 phase induction motor.

Description : State any four applications of 3 phase induction motor.

Last Answer : Applications of 3 Phase Induction Motor: 1) Lathes 2) Flour mills 3) Grinders 4) Centrifugal pumps 5) Drilling machines 6) Laundry washing machines 7) Wood working machines 8) Blowers 9 ... industries 38) For generators 39) Driving line shafts 40) For practical purposes in educational institutes.

Can you draw a DOL starter circuit?

Description : Can you draw a DOL starter circuit?

Last Answer : Refer to DOL diagram in Dennis T Hall

Develop a ladder diagram for Direct On Line (DOL) starter.

Description : Develop a ladder diagram for Direct On Line (DOL) starter.

Last Answer : Direct On Line (DOL) starter

State the function of following parts of slip ring induction motor: (i) Slip ring (ii) Fan (iii) Brushes (iv) Frame

Description : State the function of following parts of slip ring induction motor: (i) Slip ring (ii) Fan (iii) Brushes (iv) Frame

Last Answer : Sr. No. Name of part Function 1 Slip ring 1) The rotor winding terminals are permanently connected to the slip rings. 2) Connects external resistance to rotor circuit through ... It provides mechanical support to the entire internal parts of motor. 2) Protects the inner parts.

Compare squirrel cage induction motor and slip ring induction motor any four points.

Description : Compare squirrel cage induction motor and slip ring induction motor any four points.

Last Answer : Comparison Between Squirrel Cage Induction Motor and Slip Ring Induction Motor: Sr. No. Squirrel Cage Induction Motor Slip Ring Induction Motor 1 Rotor is in the form of short circuited bars ... drive e.g. Lathe machine. Used where high starting torque is required e.g. Lifts.

Describe the power and control circuit for automatic Star-Delta starter for 3-phase induction motor.

Description : Describe the power and control circuit for automatic Star-Delta starter for 3-phase induction motor.

Last Answer : Power circuit: Control circuit: 

Consider the following statements: Star delta starter is used in 3-phase induction motor

Description : Consider the following statements: Star delta starter is used in 3-phase induction motor because it  1. Prevents heating of the motor winding  2. Ensures permissible minimum starting current  3. Is regulated by electricity ... and 4 are correct (c) 1, 3 and 4 are correct (d) 1 and 2 are correct 

Last Answer : Consider the following statements: Star delta starter is used in 3-phase induction motor because it  1. Prevents heating of the motor winding  2. Ensures permissible minimum starting current  3. Is regulated by ... and 4 are correct (c) 1, 3 and 4 are correct (d) 1 and 2 are correct 

Draw power and control circuit for definite time-limit starter for slip-ring induction motor. Explain its working.

Description : Draw power and control circuit for definite time-limit starter for slip-ring induction motor. Explain its working.

Last Answer : Definite Time-limit Starter for Slip-ring Induction Motor: This starter is used for automatic control of acceleration of slip-ring induction motor at the time of starting. In this starter, the ... each phase, shorting the rotor winding terminals and final acceleration of the motor takes place. 

What is the Necessity of Starter of an Induction Motor?

Description : What is the Necessity of Starter of an Induction Motor?

Last Answer : Induction motors, when direct-switched, take five to seven times their full-load current and develop only 1.5 to 2.5 times their full-load torque. This initial excessive current is ... electrical equipment connected to the same lines. Hence, a starter is necessary to overcome this objection.

What are the advantages of star-delta starter with induction motor?

Description : What are the advantages of star-delta starter with induction motor?

Last Answer : The main advantage of using the star delta starter is reduction of current during the starting of the motor. Starting current is reduced to 3-4 times of current of Direct online starting Hence the starting current is reduced , the voltage drops during the starting of motor in systems are reduced

Why star delta starter is preferred with induction motor?

Description : Why star delta starter is preferred with induction motor?

Last Answer : Star delta starter is preferred with induction motor due to following reasons: Starting current is reduced 3-4 times of the direct current due to which voltage drops and hence it causes less ... caused. In addition, starting torque is increased and it prevents the damage of motor winding.

Develop the control circuit for star-delta starter used for starting a 3 ∅ induction motor.

Description : Develop the control circuit for star-delta starter used for starting a 3 ∅ induction motor.

Last Answer : Control Circuit for Star-Delta Starter: 1) Automatic Star-Delta Starter: OR 2) Semi- automatic Star-Delta Starter:

Develop power and control diagram for secondary frequency acceleration starter of slip ring induction motor.

Description : Develop power and control diagram for secondary frequency acceleration starter of slip ring induction motor. 

Last Answer : Power and Control Circuit diagram for secondary frequency acceleration starter of slip ring induction motor:

Draw and explain working of universal motor. Give two applications of universal motor.

Description : Draw and explain working of universal motor. Give two applications of universal motor.

Last Answer : Figure of Universal motor:   Operation of universal motor on A.C. and D.C. supply:   *A universal motor works on either DC or single phase AC supply. When the universal motor is ... , regardless of AC or DC supply, universal motor works on the same principle that DC series motor works.  

Write two application of the following motor (i) AC servo motor (ii) Stepper motor

Description : Write two application of the following motor (i) AC servo motor (ii) Stepper motor

Last Answer : (i)Applications of AC Servo Motor: 1. Computers 2. Robotics and toys 3. CD/DVD players 4. Textile industries 5. Instrument servos 6. Tracking and guidance system 7. Self- ... Laser cutters 20.Extruders 21.Engravers 22.Analytical and Medical instruments 23.Embroidery Machines 24.Packeging Machines

To check the three line fuses of a three-phase system consisting of a three-phase motor, you must _____________. A. place the starter in the 'stop' position B. make sure the motor is operating at full load to guard against a false reading C. place the leads across the 'hot' ends of the fuses D. place the leads across the bottom ends of the fuses

Description : To check the three line fuses of a three-phase system consisting of a three-phase motor, you must _____________. A. place the starter in the 'stop' position B. make sure the motor is operating at full ... leads across the 'hot' ends of the fuses D. place the leads across the bottom ends of the fuses

Last Answer : Answer: A

Which of the following actions must be carried out before a voltage tester can be used to test the three line fuses to a three-phase motor? A. The fuses must be removed from the circuit. B. The starter must be placed in the STOP position to stop the motor. C. The three line connections in the motor terminal box must be disconnected and tagged. D. Nothing need be done as long as the motor is running under a light load.

Description : Which of the following actions must be carried out before a voltage tester can be used to test the three line fuses to a three-phase motor? A. The fuses must be removed from the circuit. B. The ... disconnected and tagged. D. Nothing need be done as long as the motor is running under a light load.

Last Answer : Answer: B

Low voltage releases as used in some shipboard motor starter and control equipment will have which of the following characteristics? A. They trip circuit contactors when the motor starts to overspeed. B. They require manual resetting upon restoration of normal voltage. C. They use a phase sensitive relay to trip contacts in series with the holding coil of the starter. D. They allow the motor to restart upon restoration of normal voltage.

Description : Low voltage releases as used in some shipboard motor starter and control equipment will have which of the following characteristics? A. They trip circuit contactors when the motor starts to overspeed. B. ... coil of the starter. D. They allow the motor to restart upon restoration of normal voltage.

Last Answer : Answer: D

The diagram shown in the illustration represents a _________. EL-0058 A. dual speed, 2-winding motor controller B. navigation running light circuit C. single phase, 2-motor selectable starter D. common fluorescent lighting circuit

Description : The diagram shown in the illustration represents a _________. EL-0058 A. dual speed, 2-winding motor controller B. navigation running light circuit C. single phase, 2-motor selectable starter D. common fluorescent lighting circuit

Last Answer : Answer: B

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.

Explain the working of resistance split phase induction motor with a neat diagram.

Description : Explain the working of resistance split phase induction motor with a neat diagram.

Last Answer : Circuit diagram of resistance split single phase induction motor:   * Working of resistors split single phase induction motor: To make a single phase induction motor self-starting, we ... function is to automatically disconnected the starting winding from the supply Once motor is started. 

Explain the working of a single phase capacitor start induction motor.

Description : Explain the working of a single phase capacitor start induction motor. 

Last Answer : Single phase capacitor start induction motor https://youtu.be/31lvvzU5Puc

Explain the suitability of 3-phase induction motor for traction service.

Description : Explain the suitability of 3-phase induction motor for traction service. 

Last Answer : .embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }

explain the working of single phase induction motor.

Description : explain the working of single phase induction motor.

Last Answer : Stator has two winding namely main winding and auxiliary winding.when single phase ac supply is given to the motor,its produces alternating field.this field cut by a cage rotor.so some emf ... due to this emf,rotor flux produced.the interaction between two fluxes produce torque.so rotor rotates.

What does "(Ws Dol)" mean with regards to DVD's?

Description : What does "(Ws Dol)" mean with regards to DVD's?

Last Answer : Widescreen and Dolby Digital.

The ________ is an agency to eliminate false and misleading advertising A. FTC B. DOL C. SEBI D. Both (a) and (b)

Description : The ________ is an agency to eliminate false and misleading advertising A. FTC B. DOL C. SEBI D. Both (a) and (b)

Last Answer : A. FTC

Explain construction and working of D.C. servomotor.

Description : Explain construction and working of D.C. servomotor.

Last Answer : Construction and Working of D.C. Servo Motor: The D.C. motor that is used in servo-mechanism is called a D.C. servo motor. There are three main types of D.C. servo motor ... magnet materials used in PM motors eliminates the need for interpoles due to their excellent commutation characteristics. 

Explain the necessity of starter for D.C. motor. State various types of D.C. motor starter.

Description : Explain the necessity of starter for D.C. motor. State various types of D.C. motor starter. 

Last Answer : Necessity of Starter for D.C. Motor: Armature current is given by equation Ia = (V−Eb)/Ra i) If the motor is at standstill or rest, back emf Eb is zero (as Eb= ZNP/(60A), at start speed N ... . Types of D.C. motor starters: i) Two point starter ii)Three point starter iii) Four point starter

A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.

Description : A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.

Last Answer : The number of poles in an induction motor can be calculated using the following formula: No. of poles = (120 * frequency) / speed In this case, the number of poles would be calculated as follows: No. of poles = ( ... ) - 50 Hz = 8.08 Hz So the motor has 6 poles and a slip frequency of 8.08 Hz.

Difference between single and three phase induction motor?

Description : Difference between single and three phase induction motor?

Last Answer : inverse-square relation to the distance between them. The electromagnetic force is very strong, second only in strength to the strong interaction, but unlike that force it operates over all distances. In ... . Experiment has shown charge to be a conserved quantity, that is, the net charge within

Difference between single induction motor and 3 phase induction motor?

Description : Difference between single induction motor and 3 phase induction motor?

Last Answer : Many of these disciplines overlap with other engineering branches, spanning a huge number of specializations including hardware engineering, power electronics, electromagnetics and waves, microwave engineering, ... (IET) (formerly the IEE). Electrical engineers work in a very wide range

A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Description : A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Last Answer : Answer: A

The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip increases, rotor reactance decreases. B. The pullout point on the torque curve is about seven times the normal full load torque value. C. At stand still, stator current is 150% of normal. D. If the motor is loaded to the point where 40% slip has resulted, it will stall.

Description : The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip ... D. If the motor is loaded to the point where 40% slip has resulted, it will stall.

Last Answer : Answer: D

Which statement is true concerning a split-phase induction motor? A. Motor rotation can be reversed without changing the windings or leads. B. Motor speed can be readily adjusted from zero to full speed. C. The motor will run as a generator with the proper wiring. D. Motor rotation can be reversed by reversing the leads on the starting winding.

Description : Which statement is true concerning a split-phase induction motor? A. Motor rotation can be reversed without changing the windings or leads. B. Motor speed can be readily adjusted from zero to full ... proper wiring. D. Motor rotation can be reversed by reversing the leads on the starting winding.

Last Answer : Answer: D

A single-phase induction motor starts, comes up to about 75% rated speed, slows down to a lower speed, and accelerates again. The problem is most likely in the ____________. A. starting winding B. running winding C. starting capacitor D. running centrifugal switch

Description : A single-phase induction motor starts, comes up to about 75% rated speed, slows down to a lower speed, and accelerates again. The problem is most likely in the ____________. A. starting winding B. running winding C. starting capacitor D. running centrifugal switch

Last Answer : Answer: B

If a single-phase induction motor fails to start, the problem may be _____________. A. an open in the main winding B. a shorted shunt field C. a closed centrifugal switch D. low circuit frequency

Description : If a single-phase induction motor fails to start, the problem may be _____________. A. an open in the main winding B. a shorted shunt field C. a closed centrifugal switch D. low circuit frequency

Last Answer : Answer: A

A four-pole induction motor, operating on three-phase 60 cycle current will operate at approximately ___________. A. 850 RPM B. 1,150 RPM C. 1,750 RPM D. 3,550 RPM

Description : A four-pole induction motor, operating on three-phase 60 cycle current will operate at approximately ___________. A. 850 RPM B. 1,150 RPM C. 1,750 RPM D. 3,550 RPM

Last Answer : Answer: C

If a single-phase induction motor fails to start, the problem may be _____________. A. an open in the run winding B. a shorted shunt field C. a closed centrifugal switch D. low circuit frequency

Description : If a single-phase induction motor fails to start, the problem may be _____________. A. an open in the run winding B. a shorted shunt field C. a closed centrifugal switch D. low circuit frequency

Last Answer : Answer: A

A single-phase induction motor will only start if you spin the rotor rapidly with the line switch closed. After starting, its speed fluctuates between very slow and half-speed. The problem probably lies in the ________. A. starting winding B. centrifugal mechanism C. centrifugal switch D. running winding

Description : A single-phase induction motor will only start if you spin the rotor rapidly with the line switch closed. After starting, its speed fluctuates between very slow and half-speed. The problem ... in the ________. A. starting winding B. centrifugal mechanism C. centrifugal switch D. running winding

Last Answer : Answer: D

If a three-phase induction motor is operated under a light load and it develops an open in one of its supply lines, the motor will _____________. A. continue to run, but will vibrate and have reduced torque B. speed up due to the reduced number of poles C. run cooler due to reduced current flow D. stop

Description : If a three-phase induction motor is operated under a light load and it develops an open in one of its supply lines, the motor will _____________. A. continue to run, but will vibrate and have reduced ... speed up due to the reduced number of poles C. run cooler due to reduced current flow D. stop

Last Answer : Answer: A

A split-phase induction squirrel-cage motor will not come up to speed, even though the rated voltage, rated frequency, and rated load are applied. The suspected trouble could be due to _____________. A. a faulty centrifugal switch B. broken rotor bars C. worn bearings D. all of the above

Description : A split-phase induction squirrel-cage motor will not come up to speed, even though the rated voltage, rated frequency, and rated load are applied. The suspected trouble could be due to _____________. A. a faulty centrifugal switch B. broken rotor bars C. worn bearings D. all of the above

Last Answer : Answer: D

A three-phase, squirrel cage, induction motor will run hot due to a/an ______________. A. improper brush position B. reversed commutating pole C. shorted stator D. high power factor

Description : A three-phase, squirrel cage, induction motor will run hot due to a/an ______________. A. improper brush position B. reversed commutating pole C. shorted stator D. high power factor

Last Answer : Answer: C

A three-phase, squirrel cage, induction motor will run hot due to _____________. A. open stator coils B. high power factor C. dirty or corroded slip rings D. reversed commutating poles

Description : A three-phase, squirrel cage, induction motor will run hot due to _____________. A. open stator coils B. high power factor C. dirty or corroded slip rings D. reversed commutating poles

Last Answer : Answer: A