Current Transducer Power Supply Converter Desired SP Torque / Current PV Torque Speed Transducer Čontroller SP Desired Speed Controller PV Speed With regards to the VSD block diagram shown, at very low speeds the: O a. V/f ratio must be increased to provide a sufficient current boost. O b. output torque must be increased to support high driving loads. Oc voltage must be increased to provide adequate magnetic flux in the rotor/stator air gap. O d. output torque must be de-rated to avoid machine overheating.

Current Transducer Power Supply Converter Desired SP Torque / Current PV Torque Speed Transducer Čontroller SP Desired Speed Controller PV Speed With regards to the VSD block diagram shown, at very low speeds the: O a. V/f ratio must be increased to provide a sufficient current boost. O b. output torque must be increased to support high driving loads. Oc voltage must be increased to provide adequate magnetic flux in the rotor/stator air gap. O d. output torque must be de-rated to avoid machine overheating.

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...

See similar textbooks

Similar questions

DC Electric Machine: Working in a constant voltage and frequency network. A synchronous motor with a constant excitation current does not work at idle and as a motor. What happens when the mechanical load on the motor shaft is increased?1) Armature current increases.2) Armature current decreases.3) The load angle decreases.4) The load angle increases.5) Power factor switches to inductive.6) Power factor switches to capacitive.
QI) The induced voltage of a shunt generator is 254 V. When the machine is loaded, the terminal voltage drops down to 240 V. Determine the load current, and load power if the armature resistance is 0.04 Q, and the field circuit resistance is 24 Q You may neglect armature reaction effect. [Ans., I=340 A, P=81.6 KW]
1. A DC series motor has a rated of 25 hp, 200V, 2 000 rpm, 4 poles, 800 conductors that arranged in simplex lap winding and an armature circuit resistance is 0.012. At rated power and rated speed, the motor draws a line current of 100A. A. Calculate the flux per pole when then motor run at rated speed. B. Calculate the armature torque value that develop at rotor shaft when operates at rated- load. C. Calculate the rotational losses when the motor operates at rated power. D. Calculate the total motor efficiency.
1. In CNC machine tools, the motors used to control feed rate are: A. Servo motors B. Induction motors C. Stepper motors D. Hydraulic motors 2. The purpose of a feedback device in a CNC machine tool is to provide information of: A. Speed B. Displacement C. Force D. Both speed and displacement 3. Federate on a machining center can be specified in: A. Only feed per revolution B. Either feed per minute or feed per revolution C. Only feed per minute D. Feed per tooth per revolution 4. The correct syntax of an NC block for inclined line milling operation is: A. N-G01 X-F B. N-G01 Z-F C. N-G01 X-Y F D. N-G01 M XY F 5. When the contour or continuous path system is used, A. Tool movement from one point to the next does not have to follow a specific path. 8. Tool travel is controlled along one axis at a time. C. Machine and tool movements are precisely controlled at all times and in all planes. D. None of the above. 6. Which of the following NC blocks is correct? A. N10 G01 M03 X90 Y-15 R22 B.…
A separately excited dc generator when running at 1200 rpm supplies 200 A at 125 V to a circuit of constant resistance. Armature circuit resistance is 0.10 ohm. Determine the terminal voltage when the speed is dropped to 1000 rpm. Assume that the field current is unaltered.
(A shunt DC motor has a total resistance value for all conditions as Ra= 2 Q and under full load conditions (nominal load) armature current is Ia = 10 A. The nominal terminal Voltage for the motor is Vr-300 V and total value for field circuit resistance for all conditions is Rf=150 Q. Under full load conditions (nominal load), find the internal generated Voltage (EA), excitation circuit current (field current) (If), (total supply current flow, from electrical source) line current (IL), electrical input power (Pin) supplied from the source. Be careful about your solutions to be written readable and write the answers as it was shown below inside boxes.) EA = If = IH (IL) = Pin =
(A shunt DC motor has a total armature resistance value for all conditions as Ra= 20 and under full load conditions (nominal load) armature current is Ia = 15 A. The nominal tenninal Voltage for the motor is Vr-300 V and total value for field circuit resistance for all conditions is Rf-100 Q. Under full load conditions (nominal load). find the internal generated Voltage (EA), field current (excitation circuit current) (I), starting current (maximmum value of starting curent flow, from electrical source) (Isaet), electrical input power (Pin) supplied from the electrical source under full load (nominal load) conditions. Be careful about your solutions to be written readable and write the answers inside boxes as it was shown below.) EA - If- Izaut (Iyv) = Pin -
Consider a shunt DC motor with an armature resistance RA =0.2N and terminal voltage VT = 160 V. The motor rated speed is 1800 RPM. The total field resistance 240 Q. Assume No armature reaction in this machine. The variation of the armature terminal voltage as a function of the field current is measured under no-load conditions and shown below: IF (A) EA (V) 1.0 141 0.0 0.6 125 These values were taken at speed n= 1800 RPM 0.1 0.2 0.3 0.4 0.5 0.7 0.8 0.9 30 60 85 102 115 132 137 140 If the motor is driving a load at an armature current IA=60 A, its rotational speed is 1517 RPM, with rotational losses of 848 Watt. What torque is induced by this motor? Select one: O a. Induced Torque = 62 N.m O b. Induced Torque = 56 N.m O c. None O d. Induced Torque = 51 N.m.
A 240 V, Short – Shunt DC Generator supplies a load current of 60 A. The armature circuit resistance is 0.10 Ohms and shunt-field circuit resistance is 120 Ohms. The series-field resistance is 0.08 Ohms. Calculate The developed Power The percentage voltage regulation. Draw the power flow graph, showing the various losses as well the input, developed, and output power values. P rotational = 500W
A separately excited DC motor drives a constant torque mechanical load. The armature resistance is 0.20 and the nominal armature current is la=74A. The nominal rotational speed of the motor is 1150 rpm. The armature winding is supplied from a 220V DC source. Rotational losses can be neglected. a) What is the load torque if the machine draws the nominal armature current while running at the nominal rotational speed? b) Under the same load, the field winding current is decreased by 20%. Calculate the new rotational speed. Should the machine be kept operating in this regime for a prolonged time? Why? c) Calculate the output power and the efficiency of the machine in this regime (ignore field winding losses). d) With the same load, the field winding voltage is increased back to the nominal value. If the armature winding voltage is decreased to 180V, calculate the new rotational speed. e) Sketch the motor and the load torque-speed characteristics for the conditions in a), b) and d).…
7. The total rotational losses of an induction motor are a combination of ------- A) Friction losses B) Windage losses. D) Stray losses. C) Core losses. 8. The developed mechanical power can be calculated using the equation of- A) PAG - PRCL. B) PAG w sync C) (1-s) PAG. D) 3 E2Gc. 9. For an induction motor, if the synchronous speed is 1800 r/m, and the rotor speed 180rad/sec, then the slip will be: A) 5.5% C) 6% B) 4.5% D) 4% 10. The power losses in the stator part of the induction motor are B) Core losses D) Friction and windage losses A) Stator copper losses C) Air-gap losses
A separately excited DC generator has rated terminal voltage and full load armature current of 200 V and 50 A respectively and rated speed of 1500 rpm. The generator armature resistance R, = 0.1 0 and field resistance of R; = 100on and field voltage of 150 V. Calculate: 1. The induced emf and torque at full load. 2. The emf, armature current and terminal voltage at rated speed when the field voltage is changed to 100V. 3. The developed torque at rated speed when the field voltage is changed to 120V. 4. The emf, armature current and terminal voltage at half rated speed when the field voltage is changed to 200V.