0
Add your answer:
Earn +20 pts
What is Direct online Starter and its disadvantage?
Across the line starter has a large inrush current.
What is phase current?
A phase current is the current passing through a phase, whereas a line current is the current flowing through a line.
Why line current is greater than phase current in delta connection?
Because if you apply Kirchhoff's Current Law to the junction between the line current and the two phase currents, the line current is the phasor (vector) sum of two phase currents. For a balanced load (only), this works out to 1.732 x phase current.
Why phase current is equal to line current in star connection?
Because it is the same current, as you can determine by examining a circuit diagram of a star connection.
Do you need a starter for a 3 phase 5 horse motor?
YES. USE THE NORMAL DIRECT-ON-LINE OR ACROSS-THE-LINE STARTER.
How do you transmit ac power flow in HVDC transmission line?
You don't! That's the whole point of a d.c. transmission line.
What does the line below G in galvanometer indicate?
The Underline below symbol G represent about flow of current,if the line is straight it shows direct current,and if it is zig-zag then it is alternate current.
What is corona power loss in transmission line hvdc?
A: Transmission lines while there is ceramic insulators providing separation to the phases will have a corona if the insulators are dirty providing small current leakage ionizing the air around it therefore corona effect.
What is Direct online Starter and its disadvantage?
Across the line starter has a large inrush current.
Why you use delta star combination in transmission line from generating station to feeder station?
The starting current is about 30 % of the direct-on-line starting device. The starting torque is about 25 % of the direct-on-line starting torque. The stress on an application is reduced compared to the direct-on-line starting method.
How do you reduce spike current?
by using capacitor on the line we can reduce spike current or we can use a capacitor bank for the rated line capacity.
Distinguish between HVDC and HVAC transmission?
DC versus AC.The vast majority of electric power transmissions use threephasealternating current. The reasons behind a choice ofHVDC instead of AC to transmit power in a specific caseare often numerous and complex. Each individualtransmission project will display its own set of reasonsjustifying the choice.A. General characteristicsThe most common arguments favouring HVDC are:1) Investment cost. A HVDC transmission line costsless than an AC line for the same transmissioncapacity. However, the terminal stations are moreexpensive in the HVDC case due to the fact thatthey must perform the conversion from AC to DCand vice versa. On the other hand, the costs oftransmission medium (overhead lines and cables),land acquisition/right-of-way costs are lower in theHVDC case. Moreover, the operation andmaintenance costs are lower in the HVDC case.Initial loss levels are higher in the HVDC system,but they do not vary with distance. In contrast, losslevels increase with distance in a high voltage ACsystemAbove a certain distance, the so called "break-evendistance", the HVDC alternative will always givethe lowest cost. The break-even-distance is muchsmaller for submarine cables (typically about 50km) than for an overhead line transmission. Thedistance depends on several factors, as transmissionmedium, different local aspects (permits, cost oflocal labour etc.) and an analysis must be made foreach individual case (Fig. 3).2) Long distance water crossing. In a long AC cabletransmission, the reactive power flow due to thelarge cable capacitance will limit the maximumtransmission distance. With HVDC there is no suchlimitation, why, for long cable links, HVDC is theonly viable technical alternative.3) Lower losses. An optimized HVDC transmission linehas lower losses than AC lines for the same powercapacity. The losses in the converter stations have ofcourse to be added, but since they are only about 0.6% of the transmitted power in each station, the totalHVDC transmission losses come out lower than theAC losses in practically all cases. HVDC cables alsohave lower losses than AC cables.4) Asynchronous connection. It is sometimes difficult orimpossible to connect two AC networks due tostability reasons. In such cases HVDC is the onlyway to make an exchange of power between the twonetworks possible. There are also HVDC linksbetween networks with different nominalfrequencies (50 and 60 Hz) in Japan and SouthAmerica.5) Controllability. One of the fundamental advantageswith HVDC is that it is very easy to control theactive power in the link6) Limit short circuit currents. A HVDC transmissiondoes not contribute to the short circuit current of theinterconnected AC system.7) Environment. Improved energy transmissionpossibilities contribute to a more efficient utilizationof existing power plants. The land coverage and theassociated right-of-way cost for a HVDC overheadtransmission line is not as high as for an AC line.This reduces the visual impact. It is also possible toincrease the power transmission capacity forexisting rights of way. There are, however, someenvironmental issues which must be considered forthe converter stations, such as: audible noise, visualimpact, electromagnetic compatibility and use ofground or sea return path in monopolar operation.In general, it can be said that a HVDC system ishighly compatible with any environment and can beintegrated into it without the need to compromise onany environmentally important issues of today.
How do you measure the current by using multimeter?
The current is the amperage. It is measured in series. Voltage is measured across the line (parallel).
Is power line current ac current?
Yes it is AC. AC means Alternating Current in which the current flows first one way and then flows the other way. The current from a battery is DC, Direct Current, in which the current constantly flows one way only.
What is longest High Voltage electric transmission line in the US?
Pacific DC Intertie, a 500KV direct-current power line from The Dalles, Oregon to Los Angeles.
What is the distance between Vancouver and Quebec City?
A direct line between the two cities would measure 3789 kilometres or 2354.4 miles. Using current roads, if driving, the shortest distance between them is 4702.6 kilometres of 2922.1 miles.
When was Direct Line created?
Direct Line was created in 1985.
