DC Generator Question & AnswersNovember 1, 2021 By Wat Electrical This article lists 100 DC generator MCQs for engineering students. All the DC generator Questions & Answers given below include a solution and link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up their fundamentals on the DC generator topic which is core in Electrical Engineering.Generators are separate electrical devices or machines, used to supply electricity once electricity from the nearby grid is not available. These are classified into two types based on their output like AC generators and DC generators. These generators play a key role by providing backup power to homes, businesses, industries, organizations when there is no power supply. The main function of Generators is to change the energy from mechanical or chemical into electrical.1). For large DC loads, we connect DC generators in-------- Series Parallel Straight line Both a & c HintIn this connection, the flow of current will be in different paths2). For connecting two DC generators in parallel they should have ---? Different voltage characteristics Same Current characteristics Same Drooping voltage characteristics Same r.p.m. HintThey must have similar voltage characteristics3). Lap windings in DC generators are used for---? High voltage and High current High voltage and low current Low voltage and High current Low voltage and low current HintFor maximum current and less voltage4). For parallel connected Dc generators, the summation of the current carried by them is equal to---? Total Armature current Load current Applied source value All of the above. HintThe current at electric load5). For the DC generator, the resistance of ------is critical? Load. Brushes Field Shaft HintThe field resistance is critical6). In an idle DC generator, the % of regulation is...? 0% 5% 10% 50% HintThe regulation is zero7). The Field coils of the DC generator are made up of ----? Steel Copper Aluminum Iron HintThe chemical element of this material is Cu8). The first electrical generator was invented by…? Michael Faraday's August Toepler Paramahamsa Tewari John Read HintThe first electric generator name is Faraday disk9). DC generators are categorized into ….. Types depending on the field excitation methods? 2 3 4 5 HintThey are permanent magnets, self-excited & separately excited10). The material used to make the core lamination is? Carbon Copper Silver Silicon steel HintThese are ferritic alloys of silicon & iron11). If the generators are need to run parallel then which of the following type is used? Series generators Permanent magnet Shunt generators Compound generators HintIn this type of generator, both the windings are connected in parallel12). If the critical resistance of a DC generator is increased then…? Speed will be increased Speed will be decreased Speed resistance will be increased Speed resistance will be decreased HintThe DC motor performance will be increased13). Welding generator includes….winding? Delta Lap Wave Duplex Wave HintThis winding includes two layers14). The armature winding’s resistance mainly depends on…? Temperature Voltage Current Number of conductors used Hint It includes electrons as charge carriers15). Which of the following bearings are used to give support to the rotor shaft? Bush Ball Needle Magnetic HintIt is one kind of rolling-element bearing16). The mechanical losses within DC generators are the main function of? Voltage Current Resistance Speed HintThe operating speed of any generator is 1000rpm17). The flow of current to the external circuit in a DC generator can be given through? Slip rings Commutator Windings Bearings HintThe main function of this is to change the alternating current into pulsating direct current18). The material used to make a brushless dc machine is? Iron Copper Aluminum Carbon HintThese materials are composed of carbon atoms19). Which of the following material is used for commutator brushes? Carbon Aluminum Copper Iron HintThese materials have mainly various properties & structures.20). When the armature is….wound then equalizer rings are necessary? Lap Wave Duplex Delta HintIn electrical machines, this winding includes two layers21). Long shunt compound generator is used in automobiles for…? Battery charging Increase the performance Decrease the performance Control the speed HintThis generator is used to make the battery active in automobiles22). A DC generator can be used like a…? Rectifier Rotating amplifier Controlling device Power pump HintIt is also known as a dynamoelectric amplifier Please refer to this link to know more about DC Generators23). The field resistance is the critical resistance of….? DC Motor DC Generator DC Machines AC Machines HintThey provide power continuously to power grids & electric storage instruments.24). The working principle of dc generator is…? Ohms law Lenz’s law Faradays induction law Lorentz force HintIt is a basic law in electromagnetism25). The regulation used in DC generators is? 1% 10% 50% 100% HintOnly one percent of regulation is usedDC Generator MCQs for Interviews26). Which generator is used for long transmission line feeding? Flat compound Over compound Series Shunt HintThese generators are also called cumulative compound generators27). When a series generator is self-excited? If the current at load is zero If the current at load is not zero If the maximum current is there at load If the minimum current is there at load HintWhen there is no current at load then the generator will be self-excited.28). How the lamination of a DC generator can be done to…? Decrease the bulk By insulating core By decreasing eddy current loss By insulating the core HintThese losses are undesirable within electrical machines29). In a 4-pole DC machine, the direction of all the poles are…? South poles North poles From north to south Alternate poles are south & north HintIn four poles, alternate poles are south & north30). In a DC generator, the generated emf is directly proportional to….? Armature speed Flux Pole Windings HintIt generates a flow of current across the field31). Which of the following generator’s terminal voltage changes when load changes? Series Shunt Series compound Shunt compound HintThese types of generators are used as boosters32). In which type of generator, the poorest voltage regulation is there? Shunt Differential compounded Series Shunt compound HintThis type of generator includes both the series & shunt windings33). The connection of field windings in the separately excited generator is? Series with circuit Series with source Shunt with source Shunt with circuit HintWindings are connected in series with the source34). The brushes in DC generators are made with…? Copper Bronze Carbon & Graphite Silver HintThe brushes are made with two materials35). The connection of inter pole winding can be done in series with….winding? Field Wave Armature Lap HintIn this winding, the conversion of power takes place36). A DC shunt generator is an exciter for…? Turbogenerator Series generator Shunt generator Compound HintIt is used to connect the shaft in a steam turbine37). In electrical machines, which of the following material is used to decrease hysteresis loss…? Cast iron Silicon steel Tungsten steel Aluminum HintIt is a ferritic alloy of silicon & iron38). When the DC generator’s polarity is reversed, then,? Field current can be reversed Increases field current Motor speed will be increased Field current can be increased HintThe flow of current toward the field windings in a generator39). Lap winding is used in which machines? High current & high voltage High current & low voltage Low current & Low voltage HintUsed in machines that have max current and min voltage40). How is the magnetic field generated in DC generators? Electromagnets Windings Permanent magnets Yoke HintThese are made with wire coils to allow the electricity supply41). How many poles are there in small DC machines? 2 3 4 5 HintPoles are electromagnets in DC machines42). The most commonly used DC machines are…..? 3 Pole 4 Pole 6 Pole 8 Pole HintThe poles used in this machine are north poles43). How many parallel paths are available in triplex wave winding…..? 2 4 5 6 HintThese are found by multiplying the available poles with the number of rotations44). The type of generator used for welding is.? Cumulatively compounded generator Series generator Shunt generator Differentially compounded generator HintIn this type of generator, both the shunt and field windings are simply connected in reverse directions.45). Stray loss within a DC machine is the sum of …… and …..? Copper & mechanical losses Mechanical & iron losses Iron & armature copper losses Mechanical & iron losses HintThese losses mainly occur because of the motor’s movement and alternating flux within the transformer’s core.46). Which of the following part provides DC for a DC generator? Commutator Eyebolt Brushes Windings HintIt is a rotating electrical switch in many motors47). In commutator segments, which of the following material is used? Copper Mica Carbon Paper HintMica is mainly used for electrical insulation48). When dummy coils are used in a DC generator? To decrease eddy current losses For voltage amplification To improve flux density For providing mechanical balance to the rotor HintTo provide balance to the rotating part49). Which of the following loss has the highest proportion within DC generators? Eddy current loss Hysteresis loss Field copper loss Armature loss HintThis is also called armature reaction or effect 50). Which loss will be changed with the load current in DC machines? Field copper loss Windage loss Eddy current loss Armature copper loss HintThe loss of power like heat within the machine windingsDC Generator MCQs for Exams51). What is the function of the fractional pitch in the DC generator? Increases voltage Sparking can be reduced Improves cooling Gives protection HintIt protects the copper material so that sparking cannot occur52). Why aluminum is not used as a winding within DC machines? It is not strong It uses more space Expensive Less resistivity HintAs compared to copper, aluminum cannot be used in a fixed space53). What is the function of frog leg winding in a DC machine? It eliminates the compensating winding It eliminates equalizers within the winding Reactance voltage Controls the machine speed HintIn the lap winding of DC machines, it avoids the distribution of unequal current.54). In a DC machine, the armature MMF signal shape is? Sinusoidal Triangular Square Pulsating HintIt is a non-sinusoidal waveform55). Which of the following is used to get sparkles communication? Winding Inter poles Brushes Eyebolt HintIt is used to overcome the self-induction effect for the DC machine56). When does a series generator excite? When load current is not equal to zero When load current is zero Once the supply is provided Once the speed is increased HintOnce the maximum current is not equivalent to zero57). Once the field winding resistance in a DC generator is increased then the o/p voltage will be….? Decreased Decreased Zero None of the above HintHere, the output voltage is opposite to the resistance58). When the generator runs on no-load then which of the following type generator will have negligible terminal voltage? Shunt generator Series generator Separately excited Permanent magnet HintIn this generator, the two winding's are connected in series59). The armature MMF in a DC machine is directed through the…axis? Polar Interpolar Brush None of the above HintIt is directed on the brush axis60). The armature winding in DC machines is located on the rotor for…? Voltage generation Communication Generation of voltage Controlling the motor speed HintFor interaction purposes, it is located.61). A machine that is used to change the energy from mechanical to electrical is called? Generator Motor Transformer Battery HintMotors and generators are called machines62). Which generator provides stable voltage for different loads? Level compounded Series Permanent magnet Shunt generators HintIn this generator, the terminal voltage is the same at a fixed current63). The reciprocal of reluctance is known as? Resistance Series Inductance Permeance HintThis coefficient is used to design the magnetic circuit64). Which of the following brush has less voltage drop? Carbon Yoke pole armature Graphite Metal graphite HintThese brushes includes a brush body65). Which of the following component is used to provide DC for a DC generator? Commutator Eyebolt Windings Rotor HintIt is a rotary electrical switch66). The brushes within a commutator mainly depend on…? Commutator Windings Eyebolt Based on controlling current HintThe amount of controlling of current67). How the magnetic field can be generated within DC machines? Commutator Electromagnets Eyebolt Windings HintThese are made with wire coils68). In commutator segments, the insulating material used is…? Paper Graphite Mica Dielectric HintThis material is a group of minerals69). Which of the following material is used to make brushes? Copper Carbon Aluminum Iron HintThese materials have different structures as well as properties70). The field coils are made with? Copper Mica Aluminum Carbon HintThe chemical element of this material is Cu71). What is the name of the first electrical generator? Thomson Antonio Dynamo Faraday HintThese generators produce pulsing DC using a commutator72). The name of the first electromagnetic generator is…? Faraqday Disc Dynamo Antonio Faraday HintIt is a homopolar generator73). The electromagnetic generator was invented in which year…? 1820 1835 1831 1905 HintIt was invented by Michael faraday74). The function of an electric generator is quite opposite of…? Electric Motor Turbine Transformer Fuses HintIt converts the energy from electrical to mechanical75). How many categories are there in electromagnetic generators? 2 3 4 5 HintThey are alternators and dynamosDC Generator MCQs for Quiz76). In a DC machine, the external frame is called as? Rotor Stator Yoke Commutator HintIt is a stationary part in dc machines77). How many principal components are there in DC machines? 2 3 5 6 HintSome of them are yoke, commutator, brushes, etc.78). How the poles are connected to the yoke in DC machines? Using Welding or Bolts Using Windings Using Wires Using Magnets HintThe connection of poles can be done using the welding process79). The field system in DC generators is used to generate? Electromagnetic field Uniform magnetic field Electric field Magnetic & Electric Fields HintThis has a similar magnitude & direction 80). Practical DC machines include….? Air gaps Eyebolts Windings Commutators HintThese ranges from 0.5 mm - 1.5 mm Please refer to this link to know more about DC Machine81). Which of the following device is used to convert AC to DC and DC to AC? Commutator Eyebolts Windings Brushes Hint: It is a mechanical rectifier82). How many types of losses are there in the DC machine? 2 3 4 5 HintThey are copper, iron & mechanical Please refer to this link to know more about Types of Losses in DC Machine83). The principle used by the generator to convert the energy is? E.M.F Magnetic Induction Flemming’s left-hand rule Uniform magnetic field HintThis was discovered by Michael Faraday84). In a generator, when the power loss occurs within the armature winding then it is known as? Copper loss Eddy current loss Mechanical loss Hysteresis loss HintIt is an I2R loss85). A heat loss is called as? Copper loss Hysteresis loss Mechanical loss Eddy current loss HintThis loss mainly occurs because of the armature’s magnetic properties86). Which of the following construction is the main difference between practical and normal generators? Armature Brushes Yoke Stator HintIn a DC machine, it is a winding87). In the series-wound type, which of the following are connected with the armature in series?. Field windings Brushes Load Stator HintIt is an electromagnet88). In a shunt-wound generator, the field coils are connected in shunt with…?. Load Field windings Stator Rotor HintAn object which is lifted or moved.89). Which of the following occurs when the load changes in a generator? Voltage regulation Voltage control Current control Current regulation HintIt is an internal action90). Which of the following is used for increasing/reducing terminal voltage? Current control Voltage regulation Voltage control Current regulation HintIt is an imposed action91). When the generators are connected in parallel then they provide? More current More voltage More power More resistance HintIt provides huge electrical energy92). The special-purpose type DC generators are called as? Metadyne Amplidyne Alternator Rheostat HintThese are dc machines, used for generating huge DC93). Armature types in DC generator are? 2 3 4 5 HintThey are Gramme ring & drum type94). Once the voltage is provided to the main windings then it is known as? Self Excitation Field Excitation Excitation Voltage regulation HintIt decides the direction and strength of the magnetic field95). The generator which gets current from an external source? Series wound Separately excited Self-excited Shunt-wound HintThe coil is energized by an external source96). Which of the following generator uses their o/p voltage to strengthen field coils? Self-excited Series wound Shunt-wound Separately excited HintThey generate EMF97). The output changes with load currents directly in….generators? Self-excited Shunt-wound Separately excited Series wound HintIn this generator, the field coils with armature winding is connected in series98). The distribution of actual flux in dc generators mainly depends on…? Air gap size Windings Yoke Rotor HintIt depends on the size of an air gap99). Which of the following material is harder in a commutator? Mica Copper Silicon Silver HintIt is stronger than copper100). The voltage build-up in a shunt generator can be restricted by? Heat generated Limitation of speed Insulation Iron Saturation HintIt is measured like a percentage Time is Up! Time's up
