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20 Cards in this Set
- Front
- Back
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Transmission lines would not be used for the purposes of---- A. transmitting the highest voltage circuits on a given system B. tying together the major generating stations and primary substations C. interconnecting major electrical systems for the interchange of power D. power distribution between substations and the consumer |
D. power distribution between substations and the consumer |
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In discussing related characteristics of transmission lines, it can be said that the higher the voltage-- A. the large the conductor size B. the lower the (I^2)(R) losses C. the higher the voltage drop D. all three |
B. the lower the (I^2)(R) losses
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Electrostatic and electromagnetic unbalance between phases in a three-phase transmission line is reduced by--- A. transposing or rotating the conductors B. decreasing the space between conductors C. the delta arrangement D. lowering the charge current |
A. transposing or rotating the conductors |
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The energy stored in the magnetic fields of conductors is--- A. always lost to the system B. called the (I^2)(R) losses C. given back to the system with an increase in current or voltage D. called wattless energy |
D. called wattless energy |
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The steel core of ACSR conductors does not--- A. add to the strength of the conductor B. require corrosion protection C. carry any appreciable amount of load current D. require stranding of the steel wire |
C. carry any appreciable amount of load current |
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Suspension type insulators--- A. use a plastic binding material between the porcelain and the steel B. are not designed to resist thermal shock C. are not able to resist mechanical impact D. must be able to accept flashover without shattering |
D. must be able to accept flashover without shattering |
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Transmission line losses due to corona may be reduced by all of the below except--- A. increasing voltage value B. increasing the diameter of the conductor C. keeping the surface of the conductor as clean and smooth as possible D. increasing the spacing between conductors |
A. increasing voltage value |
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Bundled conductors--- A. increase flux density B. reduce inductive reactance C. encourage the formation of corona D. decrease the clearance requirement at the tower |
B. reduce inductive reactance |
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An electrical transmission system may be caused to drop out-of-step or become unstable by --- A. a sudden increase in load B. a sudden decrease in load C. a short-circuit D. all three |
D. all three |
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Switching performed under short-circuit conditions is apt to be most disturbing to transmission lines when--- A. done on the high-voltage side B. done on the low-voltage side C. done under no-load conditions D. all three |
B. done on the low-voltage side |
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The voltages induced in the lead sheath of underground cables may be eliminated by-- A. voltage regulators B. grounding C. gassing D. cross-bonding |
D. cross-bonding |
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A material, such as Thyrite, would most likely be used in--- A. an expulsion-type lightning arrester B. a pellet-type arrester C. a valve-type lightning arrester D. fire extinguishers |
C. a valve-type lightning arrester |
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All of the below are considered as advantages in the transmission of HVDC as compared to AC, except for --- A. its non-synchronous characteristics permits interconnection to AC systems of different frequencies B. the earth may be used as one conductor in emergencies C. the overall insulation requirements may be based on the peak rather than the actual voltages D. fault current may be limited to much lower percentages of rated current |
C. the overall insulation requirements may be based on the peak rather than the actual voltages |
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HVDC transmission lines--- A. are always subject to the effects of inductive capacitance B. can never use more than two conductors C. cannot be protected from faults by using conventional circuit breakers D. require no overhead wires for lightning protection |
C. cannot be protected from faults by using conventional circuit breakers |
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In a HVDC transmission system--- A. the quantity and direction of power flow may be controlled with high accuracy and extreme rapidity B. the amount of power transmitted is determined by the difference in phase angle between networks C. the amount of power transmitted is determined by line characteristics D. power flow is affected by load characteristics |
A. the quantity and direction of power flow may be controlled with high accuracy and extreme rapidity |
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The usual distinction between AC transmission lines and distribution lines is--- A. the amount of current carried by the lines B. the operating voltage C. the size of the conductors D. the number of conductors |
B. the operating voltage |
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Phase shift may occur between the sending and receiving ends of AC transmission lines due to--- A. the reactance of the lines B. the resistance of the lines C. voltages at which the lines operate D. conductor size |
A. the reactance of the lines |
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In a DC transmission line--- A. the effects of inductive and capacitive reactance are greater than in an AC transmission line of the same rating B. it is necessary for the sending and receiving ends to be operated in synchronism C. the effects due to capacitive and inductive reactances are minimal D. the earth cannot be used as a conductor |
C. the effects due to capacitive and inductive reactances are minimal |
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The load-carrying capability of a long AC transmission line--- A. is never limited by conductor size B. is reduced at low ambient air temperatures C. is set by the dispatcher D. may be limited by stability conditions |
D. may be limited by stability conditions |
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Which one of the conditions listed below is not affected by transposing AC transmission line conductors? A. transient voltage surges B. telephone interference C. line-to-line interference D. capacitive and inductive effects between the three phases of the circuit |
A. transient voltage surges |
