10. Excitation losses in a transformer must be determined. When running the test, you should make sure that the secondary winding A. carries exactly the rated current. B. is open-circuited. C. is short-circuited D. carries a higher current than the primary. 11. The armature of a 100-kw 250-volt shunt-wound generator has a resistance of 0.02 ohm. When the generator is operated as a motor, what input voltage should be applied across the brushes to measure the no-load losses if the brush-contact IR drop is 2 volts? A. 240 volts B. 248 volts C. 260 volts D. 252 volts

10. Excitation losses in a transformer must be determined. When running the test, you should make sure that the secondary winding A. carries exactly the rated current. B. is open-circuited. C. is short-circuited D. carries a higher current than the primary. 11. The armature of a 100-kw 250-volt shunt-wound generator has a resistance of 0.02 ohm. When the generator is operated as a motor, what input voltage should be applied across the brushes to measure the no-load losses if the brush-contact IR drop is 2 volts? A. 240 volts B. 248 volts C. 260 volts D. 252 volts

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

(5) The saturation in transformer appears: a- At no-load. b- At half-load. c- At full-load. (6) The only parts suffers from eddy currents in DC motors: a- The stator. b- The rotor. c- The stator and rotor.
er C ai Exa (B)- Select the correct answer for the alternatives given. 1- A d.c. shunt motor is running with certain load. The effect of adding an external resistance field circuit is to a)-reduce the motor speed, b)-increase the motor speed, c)- stop the motor d)- reduce the armature current of the motor 2- The copper loss and iron loss of transformer at half load are 1600 w and 5000w respectively. The copper loss and iron loss at full load will be respectively. a)-(3200 w and 10000w), b)- (6400 w and 5000 w), c)-(6400 w and 10000w), d)- (3200 w and 1250w) Way t 3- The secondary winding of which of the following transformer is always kept close b)- auto-transformer, c)- current transformer, a)-power transformer d)-distribution transformer 4- A 6-pole lap wound de shunt generator is supplying 295 A to load. The field current of generator is 5A. The current parallel path is a)-300A 245)-145A b)- 150A, c)- 50A باب الثاني
The high-voltage side of a transformer has 750turns, and the low-voltage side has 50 turns. When thehigh side is connected to a rated voltage of 120 V,60 Hz, a rated load of 40 A is connected to the lowside. Calculatea. The turns ratio.b. The secondary voltage (assuming no internaltransformer impedance voltage drops).c. The resistance of the load.
When the transformer is supplied at 400 V, 50-hz the hysteresis loss is found to be 300 W and eddy current loss is found to be 250 W. Determine the hysteresis loss when the transformer is supplied at 800 V, 100-hz.
4. In a transformer, which options are correct: A. Works on Faraday’ law and Ampere's law B. DC current in the primary winding will produce voltage output in the secondary winding C. Copper losses are caused by reluctance in magnetic circuit D. Frequency of input power source will not govern the voltage induced in secondary circuit. 5. Voltage ratio of input voltage and output voltage in IDEAL transformer depends on: A. Leakage flux B. Magnetization current C. Copper loss current D. Turns ratio 6. The core of transformer must have A. Low reluctance C. High reluctance B. High resistance D. Low resistance 7. An overexcited synchronous motor behaves like: B. Resistive load D. DC generator A. Inductive load C. Capacitive load 8. The amount of real power delivered by a synchronous generator connected to an infinite bus can be controlled by adjusting A. System frequency C. Full load frequency B. No load frequency D. Terminal voltage
AC power of 100 volts and 1 ampere enters a transformer with 2 coils and exits the transformer with 20 coils. What is the exiting voltage and current? a.) 1000v/0.1amp b.) 0.1v/1000amp c.)1000v/1amp d.) 2v/20amp e.) No change
3. If a transformer is operated at rated frequency but at voltage higher than the rated value, how do you expect the following quantities to change? a) No load current. b) Hysteresis loss. c) Eddy current
The resistance of the shunt winding of a d.c machine is measured before and after a run of several hours. The average values are 55 ohms and 63 ohms. Calculate the rise in temperature of the winding (Temperature coefficient of resistance of copper is 0.00428 ohm per ohm per °C). [36°C]
8.a. The type of coil usually used in power transformers rated at less than 15,000 volts is theA. shell-form coil.B. core-form coil.C. disk coil.D. cylindrical coil.8.b. In large power transformers, the unequal voltage distribution caused by voltage surges in the winding isprevented by the use ofA. series capacitors.B. parallel inductances.C. static shields.D. low-voltage arresters.
Flag this question for future reference What is the test that can be conducted in the laboratory to understand the transformer impedance drops are dependent on the load current with a variation in the secondary voltage? O a. Direct Load Test O b. Open Circuit Test OC. Voltage Ratio Test O d. Polarity Test
Draw and label the equivalent circuit for a transformer. Explain the principles of operation behind a transformer. How are the effects of eddy currents minimised?
Q choose the correct answer: 1-Brushless excitation system consisting of.... a- Stator field winding and power diodes b-stator and rotor field winding and capacitor c- stator and rotor field winding and capacitor d- Everything mentioned in the options 2- Voltage generated per phase in an alternator is proportional to a- Flux per pole b- Number of turns in armature c-Winding factors d- Everything mentioned in the options e- Frequency of waveform 3- If input mech. Power of SG constant, the functionality of AVR is a- Control flux of rotor b-Control terminal voltage c- Control flux and terminal voltage d-Control Load angle