Extra-low voltage (ELV) is an electricity supply voltage in a range which carries a low risk of dangerous electrical shock.
Description : What is the difference between a line voltage and low voltage control system?
Description : What is considered low voltage and high voltage?
Description : What is Extra High Voltage?
Description : Step-down transformer converts high voltage and low current into: (A) How voltage and high current (B) High voltage and low current (C) Low voltage and high current (D) None of the above
Last Answer : Step-down transformer converts high voltage and low current into: Low voltage and high current
Description : Which of the following is the least expensive protection for over current in low voltage system? (A) Rewireable fuse (B) Isolator (C) Oil Circuit breaker (D) Air break circuit breaker
Last Answer : Which of the following is the least expensive protection for over current in low voltage system? (A) Rewireable fuse (B) Isolator (C) Oil Circuit breaker (D) Air break circuit breaker
Description : What is meant by extra high voltage transmission?
Last Answer : HT & LT two types transmission in industrial line
Description : Low voltage cables are meant for use up to (a)l.lkV (b)3.3kV (c)6.6kV (d)llkV
Description : Why does surge impedance loading (SIL) increase with increase in voltage level?
Last Answer : Answer: SIL varies as the square of the operating voltage, so SIL increases with increase in voltage level
Description : Electro-mechanical voltage regulators are generally used in (a) reactors (b) generators (c) transformers (d) all of the above
Last Answer : (b) generators
Description : When an alternator connected to the bus-bar is shut down the bus-bar voltage will (a) fall (b) rise (c) remain unchanged (d) none of the above
Last Answer : (c) remain unchanged
Description : The frequency of voltage generated, in case of generators, can be increased by (a) using reactors (b) increasing the load (c) adjusting the governor (d) reducing the terminal voltage (e) none of the above
Last Answer : (c) adjusting the governor
Description : When the interconnector between two stations has large reactance (a) the transfer of power will take place with voltage fluctuation and noise (b) the transfer of power will take place with least loss ... out of step be¬cause of large angular displacement between the stations (d) none of the above
Last Answer : (c) the stations will fall out of step be¬cause of large angular displacement between the stations
Description : For transmission of power over a distance of 500 km, the transmission voltage should be in the range (a) 150 to 220 kV (b) 100 to 120 kV (c) 60 to 100 kV (d) 20 to 50 kV
Last Answer : (a) 150 to 220 kV
Description : Constant voltage transmission entails the following disadvantage (a) large conductor area is required for same power transmission (b) short-circuit current of the system is increased (c) either of the above (d) none of the above
Last Answer : (b) short-circuit current of the system is increased
Description : In a tap changing transformer, the tappings are provided on (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above
Last Answer : (b) secondary winding
Description : Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical ? (a) Static condenser (b) Synchronous condenser (c) Tap changing transformer (d) Booster transformer
Last Answer : (d) Booster transformer
Description : For transmission of power over a distance of 200 km, the transmission voltage should be (a) 132 kV (b) 66 kV (c) 33 kV (d) 11 kV
Last Answer : (a) 132 kV
Description : The voltage drop, for constant voltage transmission is compensated by installing (a) inductors (b) capacitors (c) synchronous motors (d) all of above (e) none of the above
Last Answer : (c) synchronous motors
Description : By which of the following a bus-bar is rated ? (a) Current only (b) Current and voltage (c) Current, voltage and frequency (d) Current, voltage, frequency and short time current
Last Answer : (d) Current, voltage, frequency and short time current
Description : Transmission voltage of ll kV is normally used for distances upto (a) 20—25 km (b) 40—50 km (c) 60—70 km (d) 80—100 km
Last Answer : (a) 20—25 km
Description : The power transmitted will be maximum when (a) corona losses are minimum (b) reactance is high (c) sending end voltage is more (d) receiving end voltage is more
Last Answer : (c) sending end voltage is more
Description : Which of the following is usually not the generating voltage ? (a) 6.6 kV (b) 8.8 kV (c) 11 kV (d) 13.2 kV
Last Answer : (b) 8.8 kV
Description : As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only (a) 31.25 percent of copper (b) 33.3 percent of copper (c) 66.7 percent of copper (d) 125 percent of copper
Last Answer : (a) 31.25 percent of copper
Description : Transmitted power remaining the same, if supply voltage of a D.C. 2-wire feeder is increased 100 percent, saving in copper is (a) 25 percent (b) 50 percent (c) 75 percent (d) 100 percent
Last Answer : (b) 50 percent
Description : In a D.C. 3-wire distribution system, balancer fields are cross-connected in order to (a) boost the generated voltage (b) balance loads on both sides of the neutral (c) make both machine^ run as unloaded motors (d) equalize voltages on the positive and negative outers
Description : The material generally used for armour of high voltage cables is (a) aluminium (b) steel (c) brass (d) copper
Last Answer : (b) steel
Description : The material commonly used for insulation in high voltage cables is (a) lead (b) paper (c) rubber (d) none of the above
Last Answer : (b) paper
Description : High voltage transmission lines use (a) suspension insulators (b) pin insulators (c) both (a) and (b) (d) none of the above
Last Answer : (a) suspension insulators
Description : Most of the high voltage transmission lines in India are (a) underground (b) overhead (c) either of the above (d) none of the above
Last Answer : (b) overhead
Description : The voltage of the single phase supply to residential consumers is (a) 110 V (b) 210 V (c) 230 V (d) 400 V
Last Answer : (c) 230 V
Description : Which of the following is the demerit of a 'constant voltage transmission system' ? (a) Increase of short-circuit current of the system (b) Availability of steady voltage at all loads at ... of carrying increased power for a given conductor size in case of long-distance heavy power transmission
Last Answer : (a) Increase of short-circuit current of the system
Description : The phenomenon qf rise in voltage at the receiving end of the open-circuited or lightly loaded line is called the (a) Seeback effect (b) Ferranti effect (c) Raman effect (d) none of the above
Last Answer : (b) Ferranti effect
Description : Which of the following characteristics should the line supports for transmission lines possess ? (a) Low cost (b) High mechanical strength (c) Longer life (d) All of the above
Last Answer : (d) All of the above
Description : Explain some of the methods to improve the strength of transmission system?
Last Answer : Introducing or adding of new transmission lines in to the system to avoid the overloading of the existing lines Application of devices such as series capacitors in the right location of ... system Adoption of multi-voltage levels an multi-circuits in the existing ac transmission system
Description : What are the factors that limit the maximum power transfer capability in a transmission line?
Last Answer : Answer: Some of the factors which limits the maximum power transfer are: 1. Electrical phase shift 2. Voltage drop 3. Thermal effects in the line
Description : What are the problems associated with EHV transmission?
Last Answer : Answer: The problems associated with EHV transmission are corona loss and radio interference, requirement of heavy supporting structures and insulation requirments
Description : What is the material used for overhead transmission lines?
Last Answer : Answer: ACSR conductors are employed.
Description : What for series and shunt compensation provided in EHV transmission lines?
Last Answer : Answer: Series capacitance is provided in EHV lines to artificially reduce the series reactance of the line so as to improve stability, voltage regulation and transmission efficiency Shunt compensation ... reduce the line susceptance so as to improve the voltage regulation under light load condition
Description : Series capacitors on transmission lines are of little use when the load VAR requirement is (a) large (b) small (b) fluctuating (d) any of the above
Last Answer : (b) small
Description : The angular displacement between two interconnected stations is mainly due to (a) armature reactance of both alternators (b) reactance of the interconnector (c) synchronous reactance of both the alternators (d) all of the above
Last Answer : (a) armature reactance of both alternators
Description : In the analysis of which of the following lines shunt capacitance is neglected ? (a) Short transmission lines (b) Medium transmission lines (c) Long transmission lines (d) Medium as well as long transmission lines
Last Answer : (a) Short transmission lines
Description : The effect of corona can be detected by (a) presence of ozone detected by odour (b) hissing sound (c) faint luminous glow of bluish colour (d) all of the above
Last Answer : (d) all of the above
Description : For aluminium, as compared to copper, all the following factors have higher values except (a) specific volume (6) electrical conductivity (c) co-efficient of linear expansion (d) resistance per unit length for same cross-section
Last Answer : (6) electrical conductivity
Description : Aluminium has a specific gravity of (a) 1.5 (b) 2.7 (c) 4.2 (d) 7.8
Last Answer : (b) 2.7
Description : Pin type insulators are generally not used for voltages beyond (a) 1 kV (b) 11 kV (c) 22 kV (d) 33 kV
Last Answer : (d) 33 kV
Description : The current drawn by the line due to corona losses is (a) non-sinusoidal (b) sinusoidal (c) triangular (d) square
Last Answer : (a) non-sinusoidal
Description : The use of strain type insulators is made where the conductors are (a) dead ended (b) at intermediate anchor towers (c) any of the above (d) none of the above
Last Answer : (c) any of the above
Description : In a substation the following equipment is not installed (a) exciters (b) series capacitors (c) shunt reactors (d) voltatre transformers
Last Answer : (a) exciters
Description : For which of the following equipment current rating is not necessary ? (a) Circuit breakers (b) Isolators (c) Load break switch (d) Circuit breakers and load break switches
Description : A circuit is disconnected by isolators when (a) line is energized (b) there is no current in the line (c) line is on full load (d) circuit breaker is not open
Last Answer : (b) there is no current in the line