Description : Which of the following statements concerning AC circuits is correct? A. The power factor of a resistive circuit is always zero. B. True power in an inductive circuit always equals apparent power. ... . D. Total opposition to the flow of alternating current depends upon the amount of reactive power.
Last Answer : Answer: C
Description : In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This is accomplished by opening the _____________. A. reverse power relay B. bus disconnect link C. generator bus fuse connections D. power directional relay
Last Answer : Answer: B
Last Answer : In a distribution system, in order to improve power factor, the synchronous capacitors are installed at the receiving end.
Description : What is the power factor in pure resistive , capacitive , inductive load ?
Last Answer : Answer : Power factor cosΦ = 1 in pure resistive load, cosΦ = 0 in capacitive load , cosΦ = 0 in inductive load .
Description : The operator of electrical motors should keep a constant check on the loads they carry because _____________. A. low loads necessitate frequent insulation cleaning B. exceeding nameplate values shortens ... wasted if full loading is not utilized D. power factor correction methods are load dependent
Description : The conversion of the throttle command voltage to the signal necessary to achieve the desired shaft RPM is accomplished by the _____________. A. ahead or astern function generator of the ... circuit C. operational amplifiers in the autorotation circuit D. long time constant amplifier circuit
Last Answer : Answer: A
Description : Series capacitors are used to (a) compensate for line inductive reactance (b) compensate for line capacitive reactance (c) improve line voltage (d) none of the above
Last Answer : (a) compensate for line inductive reactance
Description : In order to improve the power factor ___ device is employed in the substation a) Synchronous condenser b) Synchronous reactor c) Series Capacitors d) None of the above
Last Answer : Ans: A
Description : Voltage will always lead current in a/an ______________. A. capacitive circuit B. inductive circuit C. magnetic circuit D. resistive circuit
Description : For an Resistive Load and Inductive load considered for switching operation of circuit breaker, Switching of which load is difficult and Why?
Last Answer : In case of switching resistive load, current and voltage will be in phase i.e,when during current zero voltage also will be zero in case of resistive load. Hence the voltage at the ... maximum. This results in re-striking of arc once again. Therefore switching inductive load will be difficult
Description : The force that causes free electrons to move in a conductor as electric current flow is called a/an _____________. A. resistant force B. electromotive force C. inductive force D. dielectric force
Description : The frequency of an AC generator is controlled by the _____________. A. rheostat B. governor C. exciter D. capacitor
Description : The ratio of the effective value of the counter EMF in volts, to the effective value of the current in amperes is called _____________. A. impedance factor B. capacitive reactance C. inductive reactance D. root mean square
Description : A stand alone engine driven synchronous generator is feeding a partly inductive load. A capacitor is now connected across the load to completely nullify the inductive current. For this operating condition. ... left unaltered (D) the field current has to be reduced and fuel input left unaltered
Last Answer : A stand alone engine driven synchronous generator is feeding a partly inductive load. A capacitor is now connected across the load to completely nullify the inductive current. For this operating condition. the field current has to be reduced and fuel input left unaltered
Description : The purpose of the capacitor within component 'B' of the circuit shown in the illustration is to ____________. EL-0081 A. prolong the life of the component's contacts B. discharge the neon within ... the inductive reactance in the circuit D. store power to operate the circuit should 'D' open
Description : Power factor of an inductive circuit is usually improved by connecting capacitor to it in?
Last Answer : Power factor of an inductive circuit is usually improved by connecting capacitor to it in parallel.
Description : Federal Regulations (46 CFR) require the circuit in the illustration to _________. EL-0009 A. be at the vessel's ship's service generator distribution switchboard for normal power, normal lighting ... ground will interfere with the operation of electronic equipment D. All the above are correct
Description : Capacitors are used on the output of the power supply in today's consoles to _____________. A. filter out 'ripple' B. prevent overloads C. act as a permanent load D. decrease the average value of the output voltage
Description : When working on electrical circuits containing large capacitors, in addition to deenergizing the circuit, which of the listed precautions should also be taken? A. Keep all radio equipment ... capacitor insulation resistance. C. Ground the capacitor terminals. D. Check capacitor circuit polarity.
Description : Is there any relation between the capacitances of two capacitors used in two value capacitor start capacitor run motor?
Last Answer : Ans: Starting capacitor has about 10 – 15 times high capacity than the value of running capacitor.
Description : The existing resistance of a conductor is dependent upon its length, cross-sectional area, _____________. A. temperature and insulation B. material and insulation C. resistive coefficient and material D. material and temperature
Last Answer : Answer: D
Description : Equalization of the power factors of two alternators operating in parallel is accomplished _____________. A. manually, by adjusting the governor controls B. automatically, by automatic voltage regulators ... the output of current transformers D. automatically, by the designed action of the governors
Description : Why capacitors are used to improve power factor?
Last Answer : Capacitors generate reactive power instead of that drawn from source which is required by inductive loads.so it reduce the reactive current which is drawn from source to be drawn from capacitor.This control in Electric bills cost.
Description : The direction of propeller shaft rotation in a turbo-electric synchronous propulsion drive motor is changed by reversing the _____________. A. polarity of the propulsion motor B. polarity of the propulsion generator C. phase sequence of power to the motor D. phase sequence of power to the generator
Description : A flickering ground detection lamp on a DC system would indicate a _____________. A. multiple-ground condition in the distribution system B. ground in an armature coil of an operating machine C. ground in a motor accompanied with a short D. short between two adjacent bars of the generator commutator
Description : The most practical way to control the voltage output of an AC generator is to vary the _____________. A. number of windings B. speed of the rotating field C. strength of the rotating magnetic field D. power factor of the load
Description : The power factor at which a paralleled AC generator operates is usually adjusted by the _____________. A. connected load B. prime mover speed C. field excitation D. generator's rated voltage
Description : The unit of apparent power in a purely inductive circuit is called the _____________. A. kva B. var C. emf D. watt
Description : The apparent power in a purely inductive circuit is also known as _____________. A. true power B. lead power C. induced power D. reactive power
Description : A single phase 60 Hz generator supplies an inductive load of 4500kW at a power factor of 0.80 lagging by means of a 20 km long overhead transmission line. The line resistance and inductance are 0.0195 ohm and 0.60 mH ... voltage regulation of the line. (A) 12.59% (B) 16.34% (C) 32.68% (D) 41.15%
Last Answer : Answer is C
Description : A switchboard ammeter indicates a reading slightly above 'zero' when the leads are disconnected, this is caused by _____________. A. mechanical misalignment of the meter pointer B. a poor ground for the meter case C. static electricity in the air D. capacitors inside the meter storing charges
Description : Alternating current circuits develop resistance, inductance, and capacitance. The capacitance of individual capacitors is expressed in _____________. A. ohms B. mhos C. henrys D. farads
Description : Which of the following is/are true concerning electric power operated watertight door systems? A. Each motor driven door must use the main bus as its source of power. B. Each distribution panel for ... to permit quick activation of the system. D. Each system must have a separate branch circuit.
Description : In a logic circuit, the NOT gate function _____________. A. does not alter a logical input B. serves to amplify a given signal level C. must be accomplished with a common collector transistor arrangement D. reverses an input logic condition
Description : Cleaning of electrical insulation should be _____________. A. done every six months B. accomplished every 12 months C. determined by need and not the calendar D. performed whenever the electrician is not otherwise busy
Description : The standard method of controlling the output voltage of a 440 volt, 60 Hz, AC generator is accomplished by adjusting the ____________. A. prime mover speed droop B. number of poles C. alternator field excitation D. load on the alternator
Description : The main purpose of an electric space heater installed in a large AC generator is to _____________. A. keep the lube oil warm for quick starting B. prevent moisture from condensing in the ... is shutdown C. prevent the windings from becoming brittle D. prevent acidic pitting of the slip rings
Description : The main purpose of an electric space heater installed in a large AC generator is to _____________. A. prevent the windings from becoming brittle B. prevent moisture from condensing in the windings during ... C. prevent acidic pitting of the slip rings D. keep the lube oil warm for quick starting
Description : The purpose of DC generator brushes is to _____________. A. neutralize armature reaction B. conduct electric current to an outside circuit C. convert DC current to AC current D. provide excitation to a DC generator
Description : In an AC synchronous motor electric propulsion plant, propeller speed is controlled by varying the _____________. A. prime mover speed B. electric coupling field strength C. number of energized main motor poles D. propulsion generator field strength
Description : On some diesel-electric ships, the DC propulsion motor will only attain half speed when the generator fields are fully excited. Speeds above this are obtained by _____________. A. rotating brush ... B. raising the generator engine speed C. lowering the generator engine speed D. decreasing excitation
Description : Inductive tuning of a resonant cavity is accomplished by placing a nonmagnetic slug in what area?
Last Answer : The area of maximum H lines.
Description : When a megohmmeter is used to test insulation, the gradual rise of the pointer reading as a result of continued cranking, is caused by _____________. A. good conductor resistance B. the ... insulation C. the inductive reactance of the windings D. the dielectric-absorption effect of the insulation
Description : AC circuits develop resistance, inductance, and capacitance. The inductive reactance of a circuit is expressed in _____________. A. ohms B. mhos C. henrys D. farads
Description : The combined effect of inductive reactance, capacitive reactance, and resistance in an AC series circuit is known as _____________. A. reactance B. total reactance C. impedance D. resonance
Description : In an induction motor, rotor currents are circulated in the rotor by _____________. A. slip rings and brushes B. an armature and brushes C. inductive reaction of the rotating stator field D. external variable resistors
Description : The most inefficient method of voltage reduction from the stand point of power loss, is a/an _____________. A. capacitor in series with the load B. inductor in series with the load C. capacitor and inductor in series with the load D. resistor in series with the load
Description : Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in ... . governor speed droop setting B. voltage regulator C. balance coil D. phase-balance relay
Description : How does a capacitor improve power factor?
Last Answer : Every circuit are usually more inductive than capacitive.it means that the current lags by voltage at small angle.hence we have to compensate this situation so we use Capacitor then this lag is compensate ... angle becomes low and the value of cos(phase angle) is increase and hence power also max.
Description : When supplying emergency lighting loads, the storage battery initial voltage must not exceed the standard system voltage by more than _____________. A. 2% B. 3% C. 5% D. 10%