Insulator. What are the insulators used in over head lines? What is switchgear? Why is busbar secationalized? How many types of system loss in electrical systems and what are they?

Insulator. What are the insulators used in over head lines? What is switchgear? Why is busbar sectionalized? How many types of system loss in electrical systems and what are they?

 

 

 

Insulator. What are the insulators used in over head lines?

Answer: Insulators are: 1) Pin type insulator 2) Suspension type insulator. 3) Strain type insulator. 4) Shackle type insulator. 5) Post type insulator. 6) Stay or guy type insulators.

 

2. Why are insulators used in overhead lines?

 Write the important properties of insulators. Answer: No leakage current can go from the support to the earth because of the use of insulators. That is why insulators play an important role in transmission and distribution lines.

 

3. What qualities should the insulator have? Answer: An insulator should have the following qualities 1. Should be mechanically strong and robust. 2. High electrical resistance should be achieved. 3. Relative permittivity should be high. 4. The ratio of puncture strength and spark over voltage should be high.

 

4. What is the material of insulator? Answer: i) Porcelain ii) Glass iii) Steatite iv) Pyrex 5. How many tests are done on insulators? Answer: Three types i) Flash Over Test 350 ii) Sample Test or Performance Test iii) Routine Test 6. What is safety factor? Answer: The ratio of Puncture Strength and Flash over voltage is called safety factor. | Safety factor = Puncture strength Flashover voltage The value of safety factor is between 3 to 5.

 

What is string skill? Answer: The ratio of total voltage in the string and voltage across the disc closest to the conductor multiplied by the number of discs is called string efficiency. String skill GUIDE OPTIMUM COACHING & GUIDE OPTIMUM COACH voltage across the string nxvoltage .across disc nearest to conductor n = Number of disc’s in the string 8. Derive the equation to determine string efficiency. Answer: The figure shows the equivalent diagram of a string of 3 units: where C is the mutual capacitance and C1 is the shunt capacitance k is the output of the capacitor.

 

What do you mean by segue? Answer: The distance from the horizontal imaginary line connecting the two towers or poles to the point where it is drawn or connected to the highest point of cable sag is called sag. 2. What is span? Answer: The horizontal distance between two towers or poles is called Span

3. What is the safety factor? Answer: The ratio of ultimate or breaking stress and working stress is called safety factor. Safety factor = Breaking Stress Working Stress

 

 

What factors does sag depend on? Answer: Sag depends on the following factors: 1. Weight of conductor. 2. Length of span. 3. working tension. 4. temperature 5. Effect of storm and ice on conductor suspension. 5. Write the methods of measuring Sag. Answer: The methods of measuring Sag are a) Dynamometer b) Wave / liquid time measurement c) Sag board 6. Write the definition: a) Working Tension *) Breaking Tension Answer: Working Tension: The maximum amount of force that the conductor can work under normal conditions is called Working Tension.

Breaking Tension: The minimum amount of force at which the conductor does not work normally i.e. breaks is called Breaking Tension. 7. Why the need for sag in the transmission line? Answer: Sag is proportional to the weight of the conductor, so the more the weight of the conductor, the more the sag will be. The less the weight of the conductor the less the sag.

 

Why is it not recommended that there is too little or too much hanging on the transmission line? Answer: There should be sag in the transmission line, but not too little or too much. Because if it is too low, there is a lot of tension on the conductor and it can be torn due to the contraction of the conductor in winter. Again, if the line is too heavy, it needs strong support. If the sag is high, the conductor may be torn or short circuit by swinging due to wind pressure and wind; can That is why the conductor’s sage is kept precise by considering both sides.

 

 

What is switchgear? Ans: The combination of connecting, disconnecting, maintaining, regulating, teaching and balancing apparatus for normal and abnormal activity of electrical system is called switchgear. Such as switches, fuses, circuit breakers, isolators, relays, etc. JUM COACHING & OPTIMILY

 

Write the difference between fuse and circuit breaker. Answer: Fuse circuit breaker 1) Fuse of electric circuit One of the weakest of control and protection devices Which is a simple one with no connection in the connected circuit Simple maintenance device in case of malfunction. Automatically disconnects that circuit from supply 2) Puller opens and closes Works automatically under normal conditions. All of these can be done under normal conditions but are dangerous. 3) Operating time circuit breaker is much less than that (0.002 | More (0.1-0.5) sec close to sec) 4) Simple structure and low cost Operating time fuse is very complicated and expensive. 3. Define electrical fault. How many types of faults? What is the cause of the fault? Ans: Fault: A fault is said to occur when two or more conductors come in contact together while operating at normal voltage difference. |

 

There are two types of faults i) Symmetrical fault: The fault in the system due to which equal amount of fault current flows in each phase of the three phases is called symmetrical fault. ii) Unsymmetrical Fault: The fault in the system due to which unequal amount of current flows in each phase of the three phases instead of equal amount of current flows, is called unsymmetrical fault. Causes of Fault: ii) Sudden loss of line iv) Voltage drop GUIDE OPTIMUM COACHING & GUIDE OPTIMUM i) Insulator failure iii) Lighting surge

 

Define busbar. Answer: A busbar is a type of copper or aluminum conductive sheet or thick rod that collects electrical energy from one or more circuits and distributes that energy through one or more circuits.

 

Why is busbar sectionalized? Answer: Failure of any part of the busbar does not stop the operation of the entire busbar system. In this, the maximum success of this system is found on circuit interconnection of different sections and proper distribution in outgoing circuit etc.

 

 

Name the methods of improving string efficiency and describe any one method. IDE OPTIMUM COACHING & GUIDE OF Answer: String efficiency can be improved by following methods: a) Using long cross arms b) Grading insulator units c) Using guard rings d) Using guard rings Conducting glaze method: A large area around the line unit By electrically connecting the metal ring with the line, the voltage distribution of each unit can be uniform and string efficiency can be improved. This added new ring increases the capacitance between metal fittings and lines. Such connections exist in all units of the string. The capacitances are equal. As a result, the same amount of charging current flows through each unit, hence the voltage distribution of each unit is balanced.

 

What features should the switch gear have? Answer: a) Sensitivity OPTIMUM COACHING & GUIDE OPTIMUM COACHING & b) Detectability c) Reliability d) High speed e) Durability f) Simplicity c) Expandability

 

How many types of system loss in electrical systems and what are they? Ans: Two types, a) Technical losses i) Losses due to ohmic losses of transmission lines ii) Losses of consumables iii) Interconnected network losses iv) Losses due to feeding system v) Losses due to power plant itself b) Non-technical losses: i) Losses due to illegal connections iii ) Billing Loss D SONIHOVOO INDISITO ii) Consumption Loss iv) Collection Loss 182 DE OPTIMUM COACHING & GUIDE OPTIMUM COACHING & GUIDE OPTIMUM COACHING & GUIDE Power System / EEE Power System