Isolator in substation is open under No load condition.
Last Answer : An isolator is installed generally on both sides of a circuit breaker.
Description : Sequence of operation of isolator and circuit breaker while opening and closing
Last Answer : Sequence of operation of Isolator and C.B while opening & closing is as below: While Opening: 1. Open circuit breaker 2. Open Isolator 3. Close earthing switch While Closing: ... breaker is open 2. Open earthing switch 3. Close isolator 4. Close circuit breaker
Description : Write working of opto coupler as an isolator.
Last Answer : Optocoupler is as shown in fig. it consist of LED as an light source and phototransistor act as light detector. When input pulse is applied LED turns ON.Light emitted by LED focused on CB ... starts flowing.As input pulse reduces to zero LED turns OFF collector current becomes zero.
Description : State the condition for selecting site for distribution substation.
Last Answer : Following condition should be considered while selecting site for distribution sub-station:- 1. Near load center : Sub-station should be located near load center to reduce cost of Transmission and ... free from earthquake : To avoid damage to sub-station area should be free earth quake.
Description : What is the first equipment of the substation connected to the incoming transmission line?
Last Answer : Lightning arrestor is the first equipment of the substation connecting the incoming transmission lines. It protects other substation equipment from lightning and switching surges by suppressing them to ... between both the ends of major equipment such as power transformers for protection.
Description : What are different Bus bar materials used in Substation?
Last Answer : Busbars are generally made of copper and Aluminum. Aluminim has the advantage of one third the weight of the copper and also Aluminum requires less maintenance and proper use of alloys provide necessary rigidity required for bus material. Aluminum is used widely in EHV and HV stations
Description : What are the different electrical clearances in Substation?
Last Answer : Ground Clearance: This is the minimum distance between any live conductor and the earth or ground. Phase Clearance: It is the clearance between the different phases in a circuit or same phases in different ... The limits of work section may be ground or the platform on which the person is working.
Description : What are the different substation components
Last Answer : Circuit Breakers, Disconnecting switches, Grounding switches, Current Transformers, Potential Transformers or Capacitor voltage Transformers, Line Traps, Lightning Arrestors, Power Transformers, Shunt ... Station Buses and Insulators, Grounding system, Series capacitors and shunt capacitors.
Description : State the classification of distribution substation.
Last Answer : The classification of distribution substation. 1. Pole mounted distribution substation 2. Plinth mounted distribution substation 3. Compact/prefabricated distribution substation 4. ... Indoor distribution substation 6. Outdoor distribution substation 7. Mobile distribution substation
Description : What is the purpose of auxiliary controller in substation?
Last Answer : The systems of substation auxiliaries ensure operation of substations providing internal consumers of substations with operating direct and alternating currents. Any breakdown (loss) of auxiliary systems ... whole substation, as well as serious problems during its subsequent putting into operation.
Description : Classification of Substation According to Method of Construction
Last Answer : Classification of Substation According to Method of Construction:- 1. Indoor Substation 2. Outdoor Substation 3. Gas insulated Substation 4. Underground Substation 5. Pole mounted substation 6. Plinth Substation 7. Compact/prefabricated substation
Description : What does a substation do?
Last Answer : At the substations, power is boosted up for long distance transmission.
Description : Why EHV busbars are hallowed and circular?
Last Answer : Answer: To avoid corona effect
Description : Factors on which material of station busbar depends?
Last Answer : Some of the factors on which station busbar depends are: Current Carrying capacity Short Circuit Stresses Establishing minimum electrical clearances
Description : For distribution network which type of Switching scheme is employed?
Last Answer : For distribution network Ring Main busbar scheme is employed. It has the provision that if power interruption occurs to one bus section due to maintenance or fault, power can be fed the bus from other side of the power system.
Description : Which type of bus arrangement is costlier and more reliable?
Last Answer : One and half breaker scheme is most reliable and costlier scheme. In one and half breaker scheme 3 circuit breakers are provided for 2 bus-bars. Hence the name is coined as One and half breaker scheme
Description : What are different types of busbar arrangement Schemes in Substations?
Last Answer : Different switching schemes or busbar arrangement scheme employed in switch-yard are: Single Bus Scheme Double bus single breaker scheme Main and Transfer busbar scheme Double bus single breaker scheme Breaker and half scheme Ring main bus scheme
Description : What is the neutral point earthing and its advantages?
Last Answer : In substation all the neutrals of rotating machines, transformers, busbars and other equipment are connected to ground. Some of the advantages are: Earth fault protection is based on the method of ... , grounding of neutral helps to reduce the over-voltages which occur on the one healthy phases
Description : What is the significance of Corona rings in substations?
Last Answer : It is observed that corona discharge occurs mostly at sharp corners, edges near the conductor fixing points. Corona rings also called grading rings are hallow metallic rings having large diameter ... is reduced to much lower value Corona discharge is eliminated Dust deposition is also minimized
Description : What are the disadvantages of corona?
Last Answer : Some of the disadvantages of corona are: Corona causes power loss Corona causes unacceptable noise Corona cause radio interference
Description : What is Basic Impulse Level (BIL)?
Last Answer : Basic Impulse Level (BIL) refer to the peak value of lightning impuse voltage withstand capability of the equipment
Description : What is creepage distance?
Last Answer : Creepage distance is the shortest distance between two conducting points along the surface of the insulating material.
Description : What are different insulators employed in substations?
Last Answer : Some of the insulators employed in substations are: Pin insulators Post insulators Strain insulators Suspension insulators Hallow apparatus insulators Dead-end insulators Solid core insulators
Description : With neat diagram explain the operation of Horizontal break isolator.
Last Answer : Operation of Horizontal Break Isolator: 1) Fixed female contacts of metal are supported on stack of insulator. 2) Male contact rod is connected to central insulating support which can be ... on galvanized steel channel or steel frame. The moving male contact can be move through 90o.
Description : Which of the device is employed in substation to limit the short circuit current in the power system: a) Shunt condenser b) Reactor c) Series capacitor d) Shunt capacitor
Last Answer : Ans: B
Description : In order to improve the power factor ___ device is employed in the substation a) Synchronous condenser b) Synchronous reactor c) Series Capacitors d) None of the above
Last Answer : Ans: A
Description : Stones are provided in the substation to: a) To avoid fire accident by draining oil from transformer if leaks b) To avoid growing of weeds and plants c) To provide insulation d) All the above
Last Answer : Ans: D
Description : Locations where Gas Insulated Substation is preferred
Last Answer : Gas Insulated Substations are preferred in the places where land requirement for the substation is difficult such as in populated areas and highly polluted areas where outdoor switchyard is not ... pollution and saline environment. Under such case indoor GIS substation is very much helpful.
Description : What are different insulators used in substation
Last Answer : Different Insulators: Over head electrical conductors used for transmitting electric power is mostly bare and not covered with any insulation medium. The bare line conductors are ... Post insulators for support Stray arm insulators Shaft insulators Sectionalising insulators Connecting rod insulators
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 : Draw a block diagram of WPP substation. State function of each block.
Last Answer : Block Diagram of WPP Substation: OR Wind Turbine : Converts wind power to rotational mechanical energy Gear Box: Transfer low speed to high. Generator: Converts rotational ... to DC and vice-versa of correct frequency. Transformer: Step up the voltage to grid level.
Description : State significance of earthing. Draw and explain pipe earthing. State the values of earth resistances for : (i) Substation (ii) Residential wiring (iii) H.T. Line (iv) L.T. Line
Last Answer : Significance of earthing: * Earthing means connecting the body of the electrical equipment (it means the part which does not carries current under normal condition) to the earth. For example electrical equipment' ... surrounded by charcoal and salt. the values of earth resistances for:
Description : Write down the circuit breaker with their rating used in traction substation. Explain any one.
Last Answer : Circuit Breaker With Their Rating Used in Traction Substation: Rated capacity of a circuit breaker is 750Amps at 25 kV, 500MVA. Its overall tripping time is 0.14 seconds composed of 0.04 ... but in case of traction substation application, mostly Minimum Oil Circuit Breaker (MOCB) is preferred.
Description : Distributed under Creative Commons Attribution-ShareAlike - CC BY-SA.
Last Answer : Some important components/equipments in substation As told earlier, the function of a substation is to receive power at some voltage through incoming lines and transmit it at some other voltage through ... range ammeter to indicate the line current. Version 2 EE IIT, Kharagpur
Description : What is the difference between Isolator and Circuit Breaker?
Last Answer : Isolator is an off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintenance on downstream circuits. It is manually operated and does ... is rated current and 2 is short circuit breaking capacity and 3 is instantaneous tripping current.
Description : Does the Wire Rope Isolator dash number at the end of the model number have meaning?
Last Answer : In general it represents the number of loops in the isolator.
Description : Do the three digit Wire Rope Isolator (WRI) model index numbers have any meaning?
Last Answer : The difference between a 200, 400, 600, and 800 index number has relative meaning within a series. The larger the number the taller the isolator but the lower the isolator stiffness.
Description : What does the WR series number represent on standard Wire Rope Isolator (WRI)?
Last Answer : The number following WR represents the wire diameter in 32nd of an inch. The WRS series isolators use 5/32” diameter wire.
Description : What type of mounting option should I select on a Wire Rope Isolator (WRD?
Last Answer : Application dependent, but in general, for shock applications use mounting options "B," "D," or "E"
Description : How much damping can be expected from a Wire Rope Isolator (WRI)?
Last Answer : WRI have between 5% and 20% damping. The amount of damping is related to wire diameter and stroke. The larger the wire diameter, the more damped (and stiffer) the isolator. Damping can be less with small amplitude vibration.
Last Answer : A: Isolator is a off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintenance on downstream circuits. it is manually operated ... specification 1) rated current 2) short circuit breaking capacity and 3) Instantaneous tripping current.
Description : A component that samples the microwave signal travelling in one direction down to the transmission line A. Isolator B. Combiner C. Directional coupler D. Attenuator
Last Answer : C. Directional coupler
Description : What is the device used in fiber optic communication which consist of a receiver transmitter use to clean up and amplify digital data moving in one direction and another in the opposite direction? A. Optic compressors B. Optic retarders C. Optic isolator D. Optic regenerators
Last Answer : D. Optic regenerators
Description : A quarter wavelength devices made of crystalline calcite that changes polarization in the optic fiber communication. A. Isolator B. Retarder C. Polarizer D. Filters
Last Answer : B. Retarder
Description : How can intermodulation interference between two transmitters in close proximity reduced or eliminated? A. Through installing a band-pass filter in the antenna feed line B. Through installing terminated circulator ... high driving power D. By installing a low-pass filter in the antenna feed line
Last Answer : A. Through installing a band-pass filter in the antenna feed line
Description : Referred to as a ferrite device that can be used in lieu of a duplexer to isolate a microwave transmitter and receiver when both are connected to the same antenna. A. Isolator B. Circulator C. Coupler D. Diode.
Last Answer : B. Circulator
Description : What is the difference between circuit breaker and isolator?
Last Answer : Isolator is a disconnecting switch which is not having the making and breaking capacity. Bus coupler - 2000A Feeders - 1600 A
Description : Give the details of switchyard 220 kV CB, Isolator, CT, CVT and lightning arrestor.
Last Answer : 220 kV SF6 Circuit Breaker 1. Make - ABB 2. Air pressure blocking a. Close Block - 17.3 bar. b. Open block - 16.7 bar. c. Auto reclose block - 19 bar. 3. SF6 pressure block a. Alarm - 5. ... , storage and erection. Rated voltage : 216 kV rms. Operating voltage : 184 kV rms.
Description : What is the difference between isolator and contactor?
Last Answer : Contactor is used for on load operation. Because they are fast acting devices. They posses arc chamber and arc chutes. Arc chamber and arc chute make it easy to extinguish the arc produced during on ... acting devices. The arc time is more in slow acting devices and operated only in off load.
Description : Curl cannot be employed in which one of the following? a) Directional coupler b) Magic Tee c) Isolator and Terminator d) Waveguides
Last Answer : d) Waveguides