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In a manual shunt motor starter over load relay is connected in series and no volt relay in parallel with the load.


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

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

Description : Why does the speed of a DC shunt motor decrease as the load increases?

Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

Answer : If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens this will make armature to take heavy current, possibly burning it.

Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.

Answer : For starting a D.C. motor a starter is required because it limits the starting current to a safe value.

Description : Which type of starter is used to start the DC motor?

Description : Why starter is required for starting an induction motor?

Description : If field current is decreased in shunt dc motor, the speed of the motor (a) remains same. (b) increases. (c) decreases. (d) none of the above.

Answer : increases

Answer : In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

Answer : In a D.C. shunt motor, speed is independent of armature current.

Description : DC shunt motor

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%; }

Description : State any four applications of DC shunt motor.

Answer : Applications of DC shunt motor: 1) Lathe machines 2) drilling machines 3) milling machines 4) Printing machinery 5) Paper industry 6) centrifugal and reciprocating pumps 7) blowers 8)fans

Description : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be

Answer : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V

Description : A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is

Answer : A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is 36 Ohm

Answer : For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.

Answer : The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.

Answer : The armature torque of the D.C. shunt motor is proportional to armature current.

Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.

Answer : The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.

Answer : The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current.

Answer : If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.

Answer : D.C. shunt motors are used for driving machine tools.

Description : Draw the wiring diagram of fluorescent tube. Explain the working of choke and starter. 

Answer : Fluorescent lamp:- Operation:- When switch is ON current flows through the choke-filament no1- starter-filament no. 2- to neutral, At that time choke induces high voltage which is applied to ... at the time of starting. ii) Starter: To make and break the circuit to start the tube. 

Description : State any four advantages of soft starter.

Answer : Advantages of soft starter: 1. Very low line voltage drops on motor operation 2. Reduced energy losses in the lines 3. System efficiency increases 4. Very smooth starting & operation 5. As ... may lead to lower MD billing. 13. Less mechanical maintenance. 14. Saving in operating costs.

Description : State function of starter and ELCB. (Earth Leakage Circuit Breaker)

Answer : i) Function of Starter:- 1. To prevent the high starting current OR to minimize the starting current. 2. To give supply failure protection 3. To give over load and short circuit protection ... an installation and cut off the circuit from power supply and avoid electrical shock to the person.

Answer : Three point starter can be used for both shunt and compound motor.

Answer : A three point starter is considered suitable for shunt as well as compound motors.

Answer : A direct online starter is used for starting motors up to 5 H.P.

Description : What is an auto transformer starter?

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Description : what is the difference between four point starter and three point starter?

Answer : The only difference is in the NO VOLT COIL connection in the starter, in three point starter NVC is connected to the field whereas in four point starter it is connected separately. The advantage of using ... (for above rated speed) and lead to DEENERGISE the NVC leading to turning off of the motor.

Answer : A cumulatively compounded long shunt generator when operating as a motor would be differentially compounded long shunt.

Description : 7.24 Consider the finite-duration signal x(n) = {1,2,3,1} (a) Compute its four point DFT by solving explicitly the 4-by-4 system of linear equations defined by the inverse DFT formula. (b) Check the answer in part (a) by computing the four-point DFT, using its defination.

Answer : Handwritten Solution for Problem Number 7.24 from Digital Signal Processing 4th edition By John G. Proakis

Description : State the use of shunt and series resistance used in extension of meter.

Answer : Use of shunt and series resistance: i) Use of shunt: To extend the range of Ammeter. ii) Use of series resistance: To extend the range of Voltmeter.

Description : In which of the following transmission lines, the value of the Shunt admittance should be approximated to zero ? (A) A 66 kV 35 km long line (B) A 132 kV 200 km long line (C) A 220 kV 300 km long line (D) A 400 kV 500 km long line

Answer : In which of the following transmission lines, the value of the Shunt admittance should be approximated to zero ? (A) A 66 kV 35 km long line (B) A 132 kV 200 km long line (C) A 220 kV 300 km long line (D) A 400 kV 500 km long line

Description : Shunt compensation in an EHV line is used to (A) Improve stability. (B) Improve the voltage profile. (C) Reduce the fault level. (D) Substitute for synchronous phase modifier.

Answer : Shunt compensation in an EHV line is used to Improve the voltage profile.

Answer : The function of shunt in an ammeter is to by pass the current.

Description : The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be?

Answer : The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be 580 V.

Answer : In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.

Answer : In D.C. shunt motors as load is reduced the speed will remain almost constant.

Description : A shunt fault is characterized by (A) Increase in current, frequency and pf (B) Increase in current, reduction in frequency and pf (C) Increase in current and frequency, reduction in pf (D) Decrease in current and frequency

Answer : B

Answer : A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will be of 5 Hz.

Description : A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly?

Answer : A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly 240 V.

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

Answer : Shunt capacitance is neglected while considering short transmission line.

Description : D.C. shunt relays are made of?

Answer : D.C. shunt relays are made of many turns of thin wire.

Description : Why shunt capacitor is used?

Answer : To improve voltage at receiving end and power factor

Description : In a d.c. motor, the mechanical output power actually comes from?

Answer : In a d.c. motor, the mechanical output power actually comes from electrical input power.

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