19 Questions
Match the following types of distribution systems with their classifications based on NATURE OF CURRENT:
D.C Distribution System = Uses direct current A.C. Distribution System = Uses alternating current
Match the following types of distribution systems with their classifications based on TYPE OF CONSTRUCTION:
Overhead system = Cheaper than underground system Underground system = Used where overhead construction is impracticable
Match the following types of distribution systems with their classifications based on SCHEME OF CONNECTION:
Radial system = Type of connection system Ring main system = Type of connection system Interconnected system = Type of connection system
Match the following statements with the correct reason for the widespread use of alternating current:
Alternating voltage can be conveniently changed in magnitude by means of a transformer. = Reason for AC preference over DC Transformer enables transmission of AC power at high voltage and utilization at a safe potential. = Reason for AC preference over DC
Match the method of obtaining a 3-wire DC system with the correct description:
Two generator method = Requires two separate generators 3-wire DC generator = Consists of a standard 2-wire machine with added coils Out of balance current (I1 − I2) = Flows through the neutral wire in the two generator method High reactance and low resistance coils = Connected to diametrically opposite points in the 3-wire DC generator
Match the following advantages/disadvantages with their corresponding overhead vs underground system:
Higher current carrying capacity = Overhead system Lower inductive reactance = Underground system Longer useful life = Underground system Low maintenance cost = Underground system
Match the load currents with their respective generators in the two generator method:
I1 = Supplied by generator G1 I2 = Supplied by generator G2
Match the advantages or disadvantages with the appropriate method of obtaining a 3-wire DC system:
Principal disadvantage of two generator method = Requires two separate generators Costly method = Two generator method due to necessity of two generators
Match the following characteristics with their corresponding overhead vs underground system:
Potential electromagnetic interference with communication circuits = Overhead system Less chance of faults and service interruptions from external factors = Underground system
Match the following statements with their corresponding systems:
Useful life of more than 50 years = Underground system Maintenance cost is very low = Underground system
Match the component connected permanently to diametrically opposite points with the correct method of obtaining a 3-wire DC system:
High reactance and low resistance coils = 3-wire DC generator
Match the following features with their corresponding systems:
Causes electromagnetic interference with telephone lines = Overhead system No interference with communication circuits = Underground system
Match the following voltage levels with their corresponding primary distribution system:
11 kV = Primary distribution system 6.6 kV = Primary distribution system 3.3 kV = Primary distribution system 220 V = Secondary distribution system
Match the following terms with their correct description:
Primary distribution system = Operates at voltages somewhat higher than general utilization Secondary distribution system = Operates at lower voltages for average low-voltage consumers Step-down substation = Located between transmission system and consumers' meters Generating station = Origin of electric power transmitted at high voltage
Match the following components with their respective functions in the distribution system:
Step-down transformer = Reduces voltage from high to 11 kV in substation Conductors = Carries reduced current due to high transmission voltages Consumers' meters = End point where electrical energy is measured for billing Substations = Points where voltage is stepped down for distribution
Match the following classifications with their corresponding distribution systems:
Primary distribution system = Handles large blocks of electrical energy Secondary distribution system = Serves average low-voltage consumers 3-phase, 3-wire system = Utilized for primary distribution due to economic reasons A.C. distribution system = Electric system between step-down substation and consumers' meters
Match the method of obtaining a 3-wire DC system with the correct description:
Balancer set = Obtained from 2-wire DC system using two identical DC shunt machines coupled mechanically Neutral wire = Taken out from the junction of armatures of machines A and B in the balancer set Potential difference = Maintained equal on two sides of neutral by the balancer set Overhead vs Underground system = Distribution system mounted on poles or placed underground depending on various factors
Match the components of the balancer set with their functions:
Generator G = Supplies power to the whole system Machines A and B = Identical DC shunt machines coupled mechanically Field windings joined in series = Armatures and field windings of machines A and B connected this way Earthed junction of armatures = Point where neutral wire is taken out Balancer set = Maintains equal potential difference on both sides of neutral
Match the characteristics of overhead and underground systems with their descriptions:
Public safety = Underground system considered safer as all distribution wiring is underground Initial cost = Factor influencing choice between overhead and underground systems Overhead lines = Mounted on wooden, concrete, or steel poles carrying distribution transformers Underground system = Uses conduits, cables, and manholes under streets and sidewalks
Learn about the Two generator method for obtaining a 3-wire DC system where two shunt wound DC generators G1 and G2 are connected in series. Each generator supplies load on its own side with a neutral point obtained in between.
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