In order to reduce the harmful effects of harmonics on the AC side of a high voltage DC transmission system shunt filters are provided.
Description : In order to reduce the harmful effects of harmonics on the A.C. side of a high voltage D.C. transmission system ______are provided. (A) synchronous condensers (B) shunt capacitors (C) shunt filters (D) static compensators
Last Answer : Ans: C Xc= 1/ ωc
Description : The electrical supply applied to the anodes shown in the illustration is _____________. EL-0090 A. low voltage, high current DC B. low voltage, high current AC C. high voltage, low current DC D. high voltage, low current AC
Last Answer : Answer: A
Description : When troubleshooting electronic equipment, you should use a high impedance multimeter ________________. A. to prevent excess current flow through the meter that would damage it B. for AC measurements only ... being tested D. so as not to load down the circuit and obtain erroneous voltage readings
Last Answer : Answer: D
Description : Why is AC better for long distance power transmission than DC ?
Last Answer : ac is more economical to transmit for long distances . wires can be made smaller by step up transformer .. since major cost are wires to transmit .. then at the end of distance step down transformer is used for commercial use.
Description : For an existing ac transmission line, the string efficiency is 80%, if dc voltage is supplied for the same setup, the string efficiency will be?
Last Answer : 100%
Description : High Voltage DC (HVDC) transmission is mainly used for (A) bulk power transmission over very long distances (C) inter-connecting two systems with same nominal frequency (C) eliminating reactive power requirement in the operation (D) minimizing harmonics at the converter stations
Last Answer : High Voltage DC (HVDC) transmission is mainly used for bulk power transmission over very long distances
Description : In case of a ‘High Voltage DC’ transmission, how many minimum conductors are required?
Last Answer : In case of a ‘High Voltage DC’ transmission, how many minimum conductors are required? one
Description : If voltage at the two ends of a transmission line is 132 kV and its reactance is 40 Ohms, the capacity of the line will be: (A) 435.6 MW (B) 217.8 MW(C) 251.5 MW (D) 500 MW
Last Answer : If voltage at the two ends of a transmission line is 132 kV and its reactance is 40 Ohms, the capacity of the line will be: 435.6 MW
Description : Which of Betnovate-C and fona plus gel is more harmful to the skin ? Which has more side effects ?
Last Answer : These two creams are very effective for acne according to the advice of doctors. As far as I know, Fona Plus Gel is the best. You can safely use it. It also has fewer side effects.
Description : What are three possible causes of even-order harmonics?
Last Answer : a. Permanently magnetized heads. b. Faulty circuitry. c. Asymmetrical bias signal.
Description : The advantage of AC over DC is that (a) it contains more electrical energy (b) it is free from voltage fluctuations (c) it generation costs much less (d) it can be transmitted over long distances with minimum power loss
Last Answer : Ans:(d)
Description : A transformer is a device for (a) stepping up (or down) DC voltage (b) generating electricity (c) stepping up (or down) AC voltage (d) converting AC into DC
Last Answer : Ans:(c)
Description : A transformer – (1) converts DC to AC (2) is used to decrease or increase AC voltage (3) converts AC voltage to D.C. voltage (4) converts electrical energy into mechanical energy
Last Answer : (2) is used to decrease or increase AC voltage Explanation: Transformers have made longdistance transmission of electric power a practical reality, as AC voltage can be "stepped up" and ... the loads), voltage levels are reduced by transformers for safer operation and less expensive equipment.
Description : If the supply voltage is 220 volts 60 Hz, what is the operating voltage of the motor controller circuitry illustrated? EL-0011 A. 110 volts DC B. 110 volts AC C. 220 volts DC D. 220 volts AC
Description : A short in the shunt field of a DC motor is best located by _____________. A. visual inspection of the commutator B. applying AC voltage to each field coil and measuring the voltage drop across ... using a growler and hacksaw blade D. isolating each coil from the others and using a megohmmeter
Last Answer : Answer: B
Description : The voltage developed by an AC generator is controlled by varying the ____________. A. speed of the prime mover B. AC excitation to the field C. DC excitation to the field D. DC excitation of the voltage regulator
Last Answer : Answer: C
Description : The voltage output of an AC generator is accurately controlled by _____________. A. changing the sensitivity of the prime mover to large changes in voltage B. varying the reluctance of the air gap C. varying the DC exciter voltage D. shorting out part of the armature windings
Description : AC and DC generators are similar in that they _____________. A. both generate alternating voltages B. both rectify the voltage before delivery C. are constructed at the same physical size for the same kilowatt rating D. both supply three-phase power
Description : A transformer in an electric circuit serves to ____________. A. generate its own electrical power B. transform electrical energy into mechanical energy C. increase or decrease circuit voltage as required D. convert AC current to DC current
Description : On AC vessels, which of the following statements represents the most difficult problem involved in obtaining a DC potential suitable for use by computer components? A. A stepdown transformer is ... voltage must be rectified and made ripple free. D. Rectifiers cannot operate with voltage regulators.
Description : The most common source of excitation for synchronous motors is a/an _____________. A. low voltage battery B. motor attenuator set C. DC exciter generator D. AC supply
Description : The output voltage of a three-phase alternator is regulated by the _____________. A. AC voltage to the armature B. AC voltage to the field C. DC voltage to the armature D. DC voltage to the field
Description : An electronic device used to convert AC voltage into DC voltage is called?
Last Answer : Rectifier
Description : Why does using ac vice dc bias voltage result in a stronger output signal?
Last Answer : Because an ac bias voltage of the proper frequency and level places the input signal away from both steps in the magnetism curve. The result is two undistorted output signals that are combined into one strong output.
Description : What are three advantages of adding an ac bias voltage to the input signal instead of adding a fixed dc bias voltage?
Last Answer : a. Reproduces a stronger output signal. b. Greatly improves the SNR. c. Greatly reduces the natural tape hiss.
Description : Why does adding dc vice ac bias voltage to the input signal result in a poor signal-to-noise ratio (SNR)?
Last Answer : With dc bias, the SNR is poor because only a small portion of the magnetism curve is straight enough to use, thus the output signal is weak compared with the natural tape hiss.
Description : What component causes a generator to produce dc voltage rather than ac voltage at its output terminals?
Last Answer : A commutator
Description : The output from a full wave rectifier is (a) A pulsating uni-directional current (b) A DC voltage (c) Zero (d) An AC voltage
Last Answer : a) A pulsating uni-directional current
Description : In a simple dc circuit, voltage equals resistance multiplied by current. This is also considered true in an AC circuit if the what values of the current and voltage are used.
Last Answer : ANSWER: ROOT MEAN SQUARE (RMS) VALUES
Description : A transformer (1) converts DC to AC (2) is used to decrease or increase AC voltage (3) converts AC voltage to D.C. voltage (4) converts electrical energy into mechanical energy
Last Answer : is used to decrease or increase AC voltage
Description : An AC supply of 230 V is applied to half wave rectifier circuit. A transformer turns ratio is 20 : 1. Find i) Output DC voltage (ii) Peak Inverse Voltage (PIV)
Last Answer : Solution:
Description : Is the power line voltage available in our homes a dc or an ac voltage?
Last Answer : The power line voltage available in our homes is AC. Mobile dwellings are the most commonly DC-supplied homes and even then they tend to include AC supply for heavier loads.
Description : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be (1) unaffected (2) decreased (3) increased (4) either decreased or increased depending on the direction of the DC field
Last Answer : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be either decreased or increased depending on the direction of the DC field
Description : The purpose of the commutator and brushes on a DC generator is to _____________. A. transfer generated direct current voltage from the armature to the line B. convert the alternating voltage ... contact method to excite the field D. reduce sparking between the armature and the carbon brushes
Description : When securing an AC generator, you should FIRST ___________. A. open the generator circuit breaker B. switch the voltage regulator to 'manual' C. decrease the field excitation to minimum D. reduce the load on the unit
Description : In an AC transmission line difference in phase of voltage at two ends of the line is due to (a) System voltage (b) Insulators (c) Resistance of line (d) Reactance of line
Last Answer : reactance of line
Description : Transmission line must be matched to the load to A. transfer maximum voltage to the load B. transfer maximum current to the load C. reduce the load current D. transfer maximum power to the load
Last Answer : D. transfer maximum power to the load
Description : A DC generator is used to supply direct current in order to maintain an AC generator field and is known as a/an _____________. A. rotor B. stator C. exciter D. armature
Description : Ionisation potential employed in the industrial electrostatic precipitator is of the order of (A) 30 to 70 kV DC (B) 30 to 70 kV AC (C) 230 V AC (D) 230 V DC
Last Answer : (A) 30 to 70 kV DC
Description : Which of the following precautions should be taken when troubleshooting various power circuits using a common solenoid-type mechanical voltage tester (wiggins)? A. Never use this tester on circuits greater ... voltage expected in the circuit in order to prevent damage from an off-scale reading.
Description : State the effects of low power factor on efficiency and voltage regulation of short transmission lines.
Last Answer : i) Effect of Low power factor on efficiency:- When power factor of load reduces current drawn by transmission line increases so copper losses in transmission line increases, hence transmission ... increases, so voltage drop in transmission line increases so regulation increases. (Become Poor)
Description : Doxicap 100 mg medicine to reduce acne ? I was suggested by a medical student. And what are the side effects of this medicine ?
Last Answer : It is a good medicine for acne , you can eat it. However, for acne, it is better to take Doxicap 50mg 1 time daily for 6-12 weeks. Side effects: Nausea , headache, abdominal pain , itching may not be present in all cases.
Description : Though nitrates and calcium channel blockers are both vasodilators, they are used concurrently in angina pectoris because (a) They antagonize each other's side effects (b) Nitrates primarily reduce preload while calcium ... load (c) Nitrates increase coronary flow while calcium (d) Both (b) and (c)
Last Answer : Ans: B
Description : To reduce the risk of side effects of local anaesthetic injections; you should follow all of the following EXCEPT: A. Aspirate before injection B. Use the smallest effective volume C. Use the weakest efficient percentage strength D. Inject rapidly
Last Answer : D. Inject rapidly
Description : Though nitrates and calcium channel blockers are both vasodilators, they are used concurrently in angina pectoris, because: A. They antagonise each other's side effects B. Nitrates primarily ... primarily reduce after-load C. Nitrates increase coronary flow while calcium channel blockers reduce ca
Last Answer : B. Nitrates primarily reduce preload while calcium channel blockers primarily reduce after-load
Description : How harmonics generated in electrical power distribution system?
Last Answer : Harmonic frequencies are integral multiples of the fundamental supply frequency, i.e. for a fundamental of 50 Hz, the third harmonic would be 150 Hz and the fifth harmonic would be 250 ... the corresponding application guides, since the electricity grid's protection system should cut off the fault.
Description : What are the disadvantages of the harmonics present in the inverter system?
Last Answer : a. Harmonic currents will lead to excessive heating in the induction motors. This will reduce the load carrying capacity of the motor. b. If the control and the regulating circuits are not ... affected. d. On critical loads, torque pulsation produced by the harmonic current can be useful.
Description : Which one of the following is not correct with regard to the harmful effects of particulate matter of the size 2.5 micrometer or less? (a) It can cause respiratory problems. (b) It can directly enter ... ) It can cause inflammation and damage to the lungs. (d) It can be inhaled into the lungs.
Last Answer : (b) It can directly enter into our circulatory system.