Question 5 A 460V, 1250rpm, 30hp DC shunt motor, operating at rated conditions is to be dynamically braked by disconnecting the armature from the supply and connecting it across a 1.15 2 braking resistor. The motor has negligible armature resistance. Draw a complete schematic of the motor in the braking state. Label all components and show all relevant given quantities. Determine the following: (i) The value (exact) of armature braking current (ii) The initial braking torque. (iii) The braking power and torque when the motor speed is 250rpm.

Question 5 A 460V, 1250rpm, 30hp DC shunt motor, operating at rated conditions is to be dynamically braked by disconnecting the armature from the supply and connecting it across a 1.15 2 braking resistor. The motor has negligible armature resistance. Draw a complete schematic of the motor in the braking state. Label all components and show all relevant given quantities. Determine the following: (i) The value (exact) of armature braking current (ii) The initial braking torque. (iii) The braking power and torque when the motor speed is 250rpm.

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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Compare the compound and shunt motors by filling in the correct answer on the blanks. a) Starting current: The compound motor has a (higher/lower) starting current than the shunt motor. b) Starting torque: The compound motor has a (higher/lower). starting torque than the shunt motor. c) Efficiency: The compound motor has a (higher/lower) efficiency than the shunt motor. d) Speed regulation: The compound motor has a (higher/lower) speed regulation than the shunt motor.
Mu culty of ectrical. aduat al 1 (B)- Select the correct answer for the alternatives given. 1- When the voltage applied to the armature of a de shunt motor is decreased, what happens to the motor speed? (a) It decreases. (b) It increases, (c) The motor stops, (d) It becomes uncontrollab 2- The starting current is high in d.c shunt motor because (a) The armature resistance is small very (b) The speed of motor is equal zero AVAIR I-X2 (c) The back E.M.F is equal zero R. v (d) (a)+(b)+(c) 3- The generation of electricity achieved by moving a conductor in a magnetic field due to the relation a) E-ILB, b) E= BLV c) E-qVB) d) E-F.L.B " PZ 4- A 4-pole generator has a wave-wound armature with 722 conductors and the armature current is 60 Amper on full load. The armature m.m.f is equal b) 1353.75 A.T a) 5415 A.T c) 2707.5 A.T d) 676.675 A.T 9
Hi Please help me solve the following problems.Kindly draw the circuit diagram of each problem. Thank you very much, keep safe!
A 460V, 1250rpm, 30hp DC shunt motor, operating at rated conditions is to be dynamically braked by disconnecting the armature from the supply and connecting it across a 1.152 braking resistor. The motor has negligible armature resistance. The approximate time for the motor to come to a stop if it was plugged instead of dynamically braked. Assume a 230V supply and the same value of brake resistance and moment of inertia of the motor and connected loads. (i)
A 240-volt shunt motor takes 5 amperes on no-load. The armature resistance is 0.25 ohm and the field resistance is 200 ohms. Calculate the efficiency when taking full load current of 50 amperes and the percentage change in speed between no-load and full-load.
B. In a series of tests to determine the parameters of an eight pole, three-phase 3300 V, 50 Hz, 500 kW induction motor, the test results were obtained. The stator winding resistance was separately determined to be equal to 0.3 2, and the mechanical losses are equal to 10 kW. Table 1 Test results for wound-rotor induction machine Test Voltage Current Power No-load test 3300 V 4.711 A 10.01 kW Locked-rotor test 336.6 V 86.56 A 12.24 kW (i) Calculate the synchronous speed of the motor. (ii) If the slip at rated load is 0.02, calculate the full-load speed of the motor. Calculate the shaft torque at rated load. (iii) (iv) Using the test results in table 1, calculate the parameters of the approximate equivalent circuit. (v) If the motor is started direct-on-line, calculate the starting current, and the developed starting torque. The magnetizing branch can be neglected in this analysis. (vi) (vii) What is the disadvantage of starting big motors using direct-on-line starting? Calculate the…
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1.1. A 3-phase, 10 MVA, Salient Pole, Synchronous Motor is run off an 11 kV supply at 50Hz. The machine has Xd = 0.8 pu and Xq = 0.4 pu (using the Machine Rating as the base). Neglect the rotational losses and Armature resistance. Calculate 1.1.1. The maximum input power with no field excitation. 1.1.2. The armature current (in per unit) and power factor for this condition.
Practical Part (Question 1): A three phase, 25-hp, 460-V, 4-pole, 60-Hz, Y-connected wound-rotor induction motor has the following parameters per phase: R1 = 0.641 2 R2 = 0.332 2 X1 = 1.106 2 X2 = 0.464 2 Xm = 26.3 2 For a rotor slip of 16.667 percent at the rated voltage and rated frequency, Full load torque of the motor is 40-N.m. without the starting rheostat (short circuit) Determine the following: (a) Starting torque; Pullout torque; Synchronous Speed; No-load speed; Rated Speed; (b) 1. 2. 3. 4. 5. If the motor drives a load for which tLoad = 25N.m. Determine the following: Slip at this load; Line current; 1. 2. Induced torque of the motor, does tind = tload (Why?) Speed regulation; Efficiency; (c) 3. 4. 5. If the load on the motor increases to 20 N.m. Determine the following: Slip at this load; Line current; Speed regulation; Efficiency; What are the changes happen on the (slip, line current, speed regulation and efficiency of the motor) when the load on the motor increased…
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