List the properties of line insulators in brief

1 Answer

Answer :

Following are the properties of line insulators: 

A) Electrical Properties of insulating material:-

1. It should have high resistance.

2. It should have high breakdown voltage.

3. It should have high dielectric strength.

4. It should have low dielectric loss.

5. It should have low dielectric constant.

B) Mechanical Properties of insulating material:-

1) It should have high mechanical strength.

2) It should be tough and flexible.

3) It should be light in weight.

4) It should not be porous otherwise it increases moisture holding capacity which

reduces insulating property.

C) Chemical Properties of insulating material:-

1. It should not be hygroscopic (which absorbs moisture).

2. It should have high resistance to acid & alkaline (Chemicals).

3. It should have high resistance to oil.

D) Thermal Properties of insulating material:-

1. It should have high thermal conductivity.

2. It should be non -inflammable.

3. It should withstand at high temperature.

4. It should have thermal Stability.

5. Co-efficient of thermal expansion should be low.

E) General Properties of insulating material:-

1. It should have longer life.

2. It should have low cost

Related questions

Description : Compare pin type and suspension insulators on given points: (i) Position of insulator on cross arm. (ii) Position of conductor on insulator. (iii) Reaction on cross arm. (iv) Possibility of ... Replacement cost (vi) Maximum voltage level (vii) Effect on height of supporting structure. (viii) Life 

Last Answer : S.No  Points Pin Type insulator Suspension or Disc Type insulator 1 Position of insulator on cross arm It is fixed on top of cross arm by using galvanized steel pin. So it is ... so to maintain minimum ground clearance height of pole increase.  8 Life Less More

Description : Which have more free electrons: conductors or insulators? 

Last Answer : Conductors have many free electrons whereas insulators have very few or none at all.

Description : Name two good conductors, two good insulators, and two semiconductors.

Last Answer : In general all metals are good conductors, with silver the best and copper second.

Description : The voltages across various discs of suspension insulators having identical discs are different due to:  (A) Surface leakage currents  (B) Series capacitance of lines  (C) Shunt capacitance to ground  (D) Series and shunt capacitances

Last Answer : The voltages across various discs of suspension insulators having identical discs are different due to: Shunt capacitance to ground 

Description : State the limitations of EHVAC transmission line. 

Last Answer : Following are the Limitations of EHVAC Transmission:   1. Insulation cost increases as voltage increases 2. Skin effect is more 3. Proximity effect is more. 4. Corona loss increases. 5. Radio ... 18. EHVAC is economical only for bulk amount of power is to be transmitted over long distance. 

Description : State line parameters of transmission line. 

Last Answer : Following are the of Line parameters of transmission line:  1. Resistance  2. Inductance  3. Capacitance

Description : State the meaning of Single line diagram.

Last Answer : Meaning of Single line diagram: The single line diagram of a power system is the network which shows the main connections and arrangement of the system components along with their data ( ... breakers, transformers, capacitors, bus bars, and conductors are shown by standardized schematic symbols. 

Description : How can I access my desktop options in Properties/Display?

Last Answer : Start /Control Panel/ Display/ Desktop tab.

Description : State properties of ultrasonic waves.

Last Answer : i) Frequency of these sound waves is more than 20kHz ii) Shorter wavelength iii) They carry high amount of sound energy iv) The speed of propagation of ultrasonic waves increases with increase in ... . x) Posses certain vibrations which are used as good massage action in case of muscular pain. 

Description : Explain the suitability of aluminium as an electrical conductor with respect to its mechanical and electrical properties. 

Last Answer : Following are requirements of conductor:- i) High conductivity :  Material should have high conductivity, So that * cross section of conductor (size) reduces, * Copper losses reduces, * So Efficiency ... . Boiling point is 1820°C 9. Specific gravity is 2.7 10. High resistance to corrosion. 

Description : Explain any four properties of Moulding sand. 

Last Answer : 1. Porosity: Molten metal always contain a certain amount of dissolved gases, which are evolved when the metal freezes the molten metal coming in contact with the moist sand , generates steam or ... to the casting. Refractoriness is measured by the sinter point of the sand rather than its melting

Description : State properties of conductor material used for overhead conductor. 

Last Answer : Following are the properties of conductor material:-   1. High conductivity :- Material should have high conductivity 2. High mechanical strength:- Material should have sufficiently high mechanical strength ... available & less costly. 9. Scrap Value: - Material should have high scrap value. 

Description : State the term nuclear fuel. Also state its properties.

Last Answer : The term nuclear fuel:- Nuclear fuel is a substance that is used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear ... fuels contain heavy fissile elements 3. Nuclear fuels are complex, multi-component materials containing actinides

Description : Explain the mechanical properties of insulating materials.

Last Answer : i) Mechanical strength: Mechanical strength depends on temperature and humidity. a) Temperature: High temperature badly affects the mechanical strength of insulating material. While selecting material ... material should have property of easy moulding and machined into required shape and size.

Description : State any four properties of conducting materials.

Last Answer : Electrical properties of conductivity materials: i) Low resistivity. ii) Low temperature coefficient of resistance. iii) High conductivity. iv) Low heat dissipation.  Mechanical properties of ... properties of conductivity materials: i) Adequate resistant to corrosion. ii) Low oxidation. 

Description : The desirable properties of transformer core material are  (1) low permeability and low hysteresis loss. (2) high permeability and high hysteresis loss. (3) high permeability and low hysteresis loss. (4) low permeability and hysteresis loss.

Last Answer : The desirable properties of transformer core material are high permeability and low hysteresis loss.

Description : _______are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators.

Last Answer : Semi-conductors are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators.

Description : requirements or properties of the line supports used in transmission and distribution.  

Last Answer : Following are requirements or properties of the line supports used in transmission and distribution. 1. High mechanical strength:-  It should have high mechanical strength to withstand against - ... . 8. Appearance: It should have good appearance or They must be of pleasing shape

Description : For the women: Does a mans chin and jaw line effect whether he's more attractive?

Last Answer : I like a nice strong chin but it’s not a deal-breaker by any means.

Description : How to Spool Line Onto a Reel

Last Answer : How to Spool Line Onto a Reel If you think of fishing as a sport or a hobby, you must always make sure that you have efficient fishing tools with you all the time. Your fishing rod must ... you'll always have good quality fishing line and an efficient fishing reel to use during your fishing trips.

Description : How to Replace Edge Trimmer Line

Last Answer : How to Replace Edge Trimmer Line An edge trimmer line is a very efficient equipment for any avid gardener. This small diameter line, usually made of plastic or other material, cuts various vegetation, ... your edge trimmer lines regularly. It'll save you time and give you a great-looking landcaping.

Description : How to Repair a Brake Line

Last Answer : How to Repair a Brake Line Vehicles that often travel to colder, up-north states often have their brake lines damaged, because of the salt that melts the ice on the roads. The salt corrodes the car' ... should be done as soon as possible. Otherwise, you might end up in worst brake problems later on.

Description : State the impact of inductance and resistance on transmission line performance

Last Answer : Impact of inductance on transmission line: 1) It causes IXL drop in transmission line which affects regulation. 2) It is the only parameter which decides power transmission capacity of line i. ... is very small, it causes losses, temperature rise& poor voltage regulation so it cannot be neglected

Description : effect of inductance and capacitance on performance of transmission line.

Last Answer : Following are the effect on performance of transmission line:  1. Due to inductance (L) voltage drop in transmission line produces.  2. Capacitor (C) draws charging current ... , transmission line efficiency, voltage regulation & also power factor of transmission line gets affected. 

Description : While calculating performance of medium transmission line, what assumptions are made in case of (i) Nominal 'T' Method (ii) Nominal 'TT' Method. 

Last Answer : (i) Assumptions are made in case of Nominal 'T' Method:  a. It is assume that line capacitance is connected at center of transmission line. b. It is assume that half ... assumed that transmission line resistance & reactance per phase is connected in between two half transmission line capacitance 

Description : HVDC transmission line in India: 

Last Answer : HVDC transmission line in India:  S.N .  From To  Voltage 1 Rihand (U.P) (from 1990) Dadri +- 500 KV (bipolar) 2 Talcher- is the biggest ... (Chandrapur) Western Region  140KV   8 Connecting Southern region(Vizag- Gajuwaka) Eastern Region 140KV 

Description : effect of line parameter on performance of transmission line. 

Last Answer : Following are the effect of line parameter on performance of transmission line:  1. Due to resistance (R), voltage drop in transmission line & copper losses in transmission line ... transmission line efficiency, voltage regulation & also power factor of transmission line gets affected. 

Description : Why is transmission line 11kV, 33kV 66kV Not Is 10kV, 20kV, 30kV ?

Last Answer : 10kv plus to compensate losses in olden days 1kv were added and transmitted. Since all equipment used for transmission have a multiple of 11 from olden days, still that is being followed even though the losses are ... voltages, multiples of 11 is eazy for winding ratios.. i.e. 11kv to 33kv is 1:3.

Description : Define line regulation and load regulation.

Last Answer : Load regulation is the ability of the power supply to maintain its specified output voltage over changes in the load. Line regulation is the ability of the power supply to maintain its specified output voltage over changes in the input line voltage.

Description : Is the power line voltage available in our homes a dc or an ac voltage?

Last Answer : The power line voltage available in our homes is AC. Mobile dwellings are the most commonly DC-supplied homes and even then they tend to include AC supply for heavier loads.

Description : Define load and line regulation.

Last Answer : 1. Load regulation : The load regulation indicates how much the load voltage changes when the load current changes. The load regulation is defined as:  % Load regulation = (VNL-VFL) / VFL *100  ... the power supply. A well-regulated power supply can have a line regulation of less than 0.1%.  

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 : A 50Ω transmission line is terminated in an impedance of 20-j50. What will be the reflection coefficient? A) 0.69 B) 1.69 C) 6.9 D) 16.9 

Last Answer : A 50Ω transmission line is terminated in an impedance of 20-j50. What will be the reflection coefficient? A) 0.69 B) 1.69 C) 6.9 D) 16.9 

Description : The command line interpreter that enables the users to interact with operating system is called the A) Window B) Shell C) Process D) Kernel 

Last Answer : The command line interpreter that enables the users to interact with operating system is called the Shell 

Description : Stability of a transmission line can be increased by

Last Answer : Stability of a transmission line can be increased by Shunt capacitor, Series capacitor

Description : The sag of a transmission line is least affected by (A) Self weight of the conductor. (B) Temperature of the surrounding air. (C) Current through the conductor. (D) Ice deposited on the conductor.

Last Answer : The sag of a transmission line is least affected by Current through the conductor.

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 : In a transmission line if booster transformers are to be used, preferred location will be  (A) At the receiving end (B) At the sending end (C) At the intermediate point (D) Anywhere in the line 

Last Answer : In a transmission line if booster transformers are to be used, preferred location will be At the intermediate point

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 : A transmission line has 1 P.0 impedance on a base of 11 KV, 100 MVA. On a base of 55 KV. it will have a P.0 impedance of

Last Answer : A transmission line has 1 P.0 impedance on a base of 11 KV, 100 MVA. On a base of 55 KV. it will have a P.0 impedance of 0.02 P.U

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 : For a short transmission line with r/x ratio of is 1.0, the regulation will be zero when the load power factor is

Last Answer : For a short transmission line with r/x ratio of is 1.0, the regulation will be zero when the load power factor is 0.707 lead

Description : A transmission line of 200 km has a certain A, B, C and D parameters. If the length is reduced to 60 km

Last Answer : A transmission line of 200 km has a certain A, B, C and D parameters. If the length is reduced to 60 km A increases, B decreases

Description : If an unsymmetrical line to ground fault occurs at the secondary terminals of a delta/star, ungrounded transformer, then  (A) zero sequence currents are present on both sides of the transformer  (B) ... side  (D) zero sequence currents are present on the primary side but not on the secondary side

Last Answer : If an unsymmetrical line to ground fault occurs at the secondary terminals of a delta/star, ungrounded transformer, then zero sequence currents are absent on both sides of the transformer 

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 : Series capacitive compensation in EHV transmission line is used to

Last Answer : To maintain voltage stability 

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 : The line current in a balanced delta system is 30 A. The load current is (A) 30√3 A (B) 30/√3 A (C) 10 A (D) 30/√2 A

Last Answer : The line current in a balanced delta system is 30 A. The load current is 30/√3 A

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.

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

Last Answer : Vscos¢s-Vrcos¢r=IR