# Which relays are used for phase faults on long line?

Impedance relays are used for phase faults on long line.

## Related questions

Description : IDMT relays are used to protect the transformer against :  (A) Internal short -circuits (B) Open circuits (C) External short circuits (D) Oil leakage

Last Answer : IDMT relays are used to protect the transformer against : External short circuits

Last Answer : The inverse definite mean time relays are used for over current and earth fault protection of transformer against internal short-circuits.

Last Answer : The single phasing relays are used for the protection of three phase motors.

Description : For a 500 Hz frequency excitation, a 50 km long power line will be modeled as

Last Answer : For a 500 Hz frequency excitation, a 50 km long power line will be modeled as long line

Description : what is mean by long transmission line ?

Last Answer : The transmission line which have length more than 250 km are known as long transmission lines.

Last Answer : Reactance relay is preferred for phase fault on short transmission line.

Last Answer : Large internal faults are protected by merz price percentage differential protection.

Description : Draw a neat sketch and explain the accessory used to support long work.

Last Answer : Accessory to support long work: A steady rest is a tool for a lathe, enabling a machinist to make deep cuts in long, slender stock, bore out thin pieces of metal, and generally keeps thin stuff straight. ... tool that follows the cutter, a steady rest is firmly attached to the bed of a lathe.

Description : Write the relation between phase and line current, phase and line voltage for Star connection.

Last Answer : Line voltage is equal to root three times of phase voltage and line and phase currents are equal in star connection

Description : For 11kV line the inductance per km per phase will be of the order of:  (A) 1 H (B) 0.1 H (C) 1 mH (D) 0.1 mH

Last Answer : For 11kV line the inductance per km per phase will be of the order of: 1 mH

Description : What is the difference between line and phase current?

Last Answer : The currents flows through phase lines is called line voltage and currents flows from phase to neutral line is called phase current

Description : What is the difference between line and phase voltage?

Last Answer : Line voltage  is  voltage  between two  phases R &Y  (415 v)  while  phase  voltage  is  the  voltage  between  one  phase and  a neutral  B &  N   (240 v).

Description : What is the voltage in 3 phase line?

Last Answer : between 430 to 440 v

Last Answer : Discrimination between main and back up protection is provided by the use of relays which are slow.

Last Answer : To protect most of the electrical equipment handling low power, the types of relays used are thermocouple, electronic and bimetallic.

Last Answer : Protective relays are devices that detect abnormal conditions in electrical circuits by measuring constantly the electrical quantities which differ during normal and abnormal conditions.

Last Answer : Directional relays are based on flow of power.

Description : D.C. shunt relays are made of?

Last Answer : D.C. shunt relays are made of many turns of thin wire.

Last Answer : Thermal overload relays are used to protect the motor against overcurrent due to heavy loads.

Last Answer : Overload relays are of induction, solid state, thermal, electromagnetic type.

Last Answer : Relays can be designed to respond to changes in resistance, reactance or impedance voltage and current, light intensity, temperature.

Description : Shunt compensation in an EHV line is used to (A) Improve stability. (B) Improve the voltage profile. (C) Reduce the fault level. (D) Substitute for synchronous phase modifier.

Last Answer : Shunt compensation in an EHV line is used to Improve the voltage profile.

Description : Series capacitive compensation in EHV transmission line is used to

Last Answer : To maintain voltage stability

Description : The ALE line of an 8085 microprocessor is used to (A) latch the output of an I/O instruction into an external latch. (B) deactivate the chip-select signal from memory devices. (C) find the interrupt ... of the TRAP interrupt. (D) latch the 8 bits of address lines AD7-AD0 into an external latch.

Last Answer : The ALE line of an 8085 microprocessor is used to latch the 8 bits of address lines AD7-AD0 into an external latch.

Last Answer :  Sandwich type winding is used in 3 phase shell-type transformer.

Description : Consider the following statements. Which of these statements are correct ?  (1) Reactance relays are preferred for ground fault relaying  (2) Impedance relays are most suitable for:protecting long transmission lines  (3) Mho relays are best ... (1) and (3) (C) (2) and (4) (D) (1), (2) and (4)

Last Answer : Consider the following statements. Which of these statements are correct ?  (1) Reactance relays are preferred for ground fault relaying  (2) Impedance relays are most suitable for:protecting long transmission lines  (3) Mho relays are ... (1) and (3) (C) (2) and (4) (D) (1), (2) and (4)

Description : Reactance relays are employed for Phase faults in : (A) Short lines (B) Medium lines (C) Long lines (D) Any line

Last Answer : Reactance relays are employed for Phase faults in : Short lines

Description : The surge impedance for over head line is taken as  (1) 10-20 ohms (2) 50-60 ohms (3) 100-200 ohms (4) 1000-2000 ohms

Last Answer : The surge impedance for over head line is taken as 100-200 ohms

Description : A lightening arrester connected between the line and earth in a power system  (1) protects the terminal equipment against travelling surges (2) protects the transmission line against direct ... suppresses high frequency oscillations in the line (4) reflects back the travelling wave approaching it

Last Answer : A lightening arrester connected between the line and earth in a power system protects the terminal equipment against travelling surges

Description : The reactive power transfer over a line mainly depends on

Last Answer : The reactive power transfer over a line mainly depends on lVsl- lVRl

Description : lf a travelling-wave travelling along a loss-less overhead line does not result in any reflection after it has reached the far end, then the far end of the line is

Last Answer : lf a travelling-wave travelling along a loss-less overhead line does not result in any reflection after it has reached the far end, then the far end of the line is terminated into a resistance equal to surge impedance of the line

Description : Transmission efficiency of a transmission line increases with the

Last Answer : Transmission efficiency of a transmission line increases with the increase in power factor and voltage

Last Answer : The inductive interference between power and communication line can be minimized by transposition of the power line, transposition of the communication line.

Last Answer : When a wave propagates on a transmission line, it suffers reflection several times at sending and other end.

Last Answer : The interaction between a transmission line and communication line is minimized by transposing transmission as well as communication lines, increasing the height of the transmission line tower, increasing the distance between the two lines.

Last Answer : When a transmission line is energized, the wave that propagates on it is current wave and voltage wave.

Last Answer : A transmission line is protected by distance protection, time graded and current graded overcurrent protection.

Description : Why is AC better for long distance power transmission than DC ?

Last Answer : ac is more economical to transmit for long distances . wires can be made smaller by step up transformer .. since major cost are wires to transmit .. then at the end of distance step down transformer is used for commercial use.

Description : The standard for long distance analog signal transmission in process control industry is (A) 4-20 mV (B) 0-20 mA (C) 4-20 mA (D) 0-5 V

Last Answer : The standard for long distance analog signal transmission in process control industry is 4-20 mA

Last Answer : Power for lighting in passanger coach, in a long distance electric train, is provided through individual generator of bogie and batteries.

Last Answer : A cumulatively compounded long shunt generator when operating as a motor would be differentially compounded long shunt.

Description : relays are used for phase faults on long line. (a) Impedance (b) Reactance (c) Either of the above (d) None of the above

Description : The sending end and receiving end voltages of a three-phase transmission line are 10 kV/ph and 9.5 kV/ph, respectively. If the resistance drop is 150 V/ph and receiving end power factor is 0.8, the sending end power factor is (A) 0.745 lagging (B) 0.775 lagging (C) 0.8 lagging (D) 0.85 lagging

Description : Light triggering is mainly used in

Last Answer : Light triggering is mainly used in High voltage direct current transmission

Description : A relay used for protection of motors against overload is :  (A) Impedance relay (B) Electromagnetic attraction type (C) Thermal relay (D) Buchholz's relay

Description : Earthing switch is used for?  (A) Measuring of safety voltage (B) Protection of equipment from ground faults (C) Discharging residual energies (D) All of the above

Last Answer : Earthing switch is used for?  (A) Measuring of safety voltage (B) Protection of equipment from ground faults (C) Discharging residual energies (D) All of the above

Description : Auto reclosing is used in case of

Last Answer : Auto reclosing is used in case of air blast C.B.

Description : A negative sequence relay is used for protection of  (1) Generator (3) Motor (2) Transformer (4) Long Transmission lines

Last Answer : A negative sequence relay is used for protection of Generator

Description : The material used in liquid fuses is  (1) SF6 (3) carbon tetra chloride (2) distilled water (4) transformer oil

Last Answer : The material used in liquid fuses is  carbon tetra chloride

Description : Series reactors are used to

Last Answer : Series reactors are used to bring down the fault level within the capacity of the switchgear