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How long does it take the voltage to go from zero to maximum on a 60 Hz power line?
Wiki User
∙ 12y ago
The voltage on a utility power line, graphed against time, is the shape of a nice,
smooth sine function. At 60 Hz, it goes through 60 complete wiggles every second.
So it rises from zero to maximum in 1/4 of 1/60th of a second =
1/240 = 0.004167 second (rounded)
That's 4 1/6 milliseconds
Wiki User
∙ 12y ago
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Which mode of transmission would result in less energy loss high current and low voltage or low current and high voltage Explain your reason?
low current high voltage power dissipation in power line = I2R the resistance of the power line is hard to reduce, especially when it is a long transmission line. but reducing the current through the line reduces losses as the square, a dramatic savings. reducing voltage would have no effect and would dramatically increase losses due to increase in current to try to deliver same power.
Could it be dangerous to connect an alternator to a long transmission line if the line had a high capacitance?
Yes. Because... If we connect an alternator to a transmission line of high capacitance the line voltage will increase and caused a line voltage difference, which does not satisfied the condition of parallel operation of same voltage rating. [By Akhtaruzzaman08]
Why does the national grid use different voltages?
When transferring power over distance, the designer of the power line selects a voltage that optimizes the amount of power that is transferred, ie, minimizes the amount of power that is lost. There are tradeoffs in the selection of a voltage for a transmission line, as there are in almost any aspect of design. Too low a voltage (which requires a higher current) results in increased resistive losses in the lines, or you have to use heaver wire, which increases costs, not just of the wire, but of the stronger towers needed to support the wire. Too high a voltage leads to corona discharge losses and losses due to capacitance between lines and lines to ground. In addition, an AC voltage can be easily changed from one voltage to another with very small loss in power. So bottom line, each distribution line has a voltage selected to be optimum for that line. Connections between lines of different voltages are easily done via transformers.wire has inherent resistance. Power lost in this resistance is equivalent to P = I*I*R, where I is the current. Reducing the amount of current will reduce the inherent losses due to transporting power long distances. Power is equivalent to P = V*I; So, if we reduce the current, we must increase the voltage to maintain the same amount of power.Simply put, it is much more efficient. There is less loss transmitting the same amount of power down a line using high voltage rather than a lower voltage. Let's look and see why. Consider that the transmission lines have resistive properties (in ohms/foot). These represent a fixed loss; we can't get around them. We start with Ohm's Law: V=IR, and the definition of Power: P=VI. Substituting IR for V, we see that P=I²R. What this tells us is that the amount of power lost in the lines is equal to the square of the current flowing through the lines, times the resistance of the lines. The amount of power transmitted is constant, and the resistance in the lines is constant. So, if we double the voltage, the current is cut in half, and the losses are cut in quarter. The simple mathematics drives (dictates) that we use as high a voltage as is practical to transmit power over long lines to minimize the loss.
What is use of substaion near grid station?
A power substation is used to reduce the voltage from high voltage power lines to a voltage that is less dangerous that you can use in a house for example. It is less costly to transmit electrical energy over long distances using high voltage.
What is equivalent of 50 voltage ampere rating to wattage?
The short answer: they are identical: 50VA (through a resistive load) = 50WattsThe long answer:Power can be divided into real power and reactive power. Real power is used to do real work. reactive power is stored and released in reactive elements (capacitors and reactors). A purely resistor is hard to get, having absolutely no reactance or capacitance. Because of this, watts defines the amount of real power available to do work; volt-amps defines the maximum current drawn at a specified voltage.
Which mode of transmission would result in less energy loss high current and low voltage or low current and high voltage Explain your reason?
low current high voltage power dissipation in power line = I2R the resistance of the power line is hard to reduce, especially when it is a long transmission line. but reducing the current through the line reduces losses as the square, a dramatic savings. reducing voltage would have no effect and would dramatically increase losses due to increase in current to try to deliver same power.
Why the voltage drop is very important in distribution lines but not so important in transmission lines?
A distribution line is delivering power. Voltage drop reduces the amount of power delivered. A transmission line is typically delivering information and as long as there is sufficient signal level to deliver the information you are good to go.
How much power can a transmission line carry example how much power can a 69kv line carry compared to a 390kv line what is the formula for power capacity of a hvac line?
For a line of given cross section and material, the power capacity will depend on the current carried, since resistance heating is proportional to (current)2 . For a given power, current is inversely proportional to voltage. Thus raising the voltage from 69 to 390 kv would reduce the current by a factor 69/390 = 0.177 , for the same power transmission, and reduce the heating losses by 0.1772 = 0.031. So you can see why high voltage for long distance lines is essential. Obviously the limiting current on a power line has to be set by economic and practical considerations, but if this is predetermined and set, the limiting power will be that which produces that limiting current, and power = voltage x current. The actual limiting curent will depend on the line cross section, material, and length. The power that a line of a certain voltage can carry is calculated by using the following formula: (2.55×(KV)2 /1000) MW.
Need of ehv transmission lines?
Carry electrical power over extremely long distanceswith minimal I2*R losses. The higher the line voltage the lower the current the line has to carry to transmit the power from source to load.
Why step up transformer is required to send energy at long distances How energy losses reduces by using step up voltage while sending it to long distances?
Power is basically voltage times current. The power lines have resistance and that causes a loss of some power in transmitting the power over long lines. When the power is sent at a higher voltage, the current is lower, which means that the power lost in the wires is less. A rule of thumb for power transmission is to use 1000 volt per kilometre so for a 33 km line you would use 33 kV.
Why the power station that produce 11KV be increase to 257KV?
Because it is much more efficient to transfer power over a long distance at a high voltage. The higher the voltage the lower the current (amps) and heating losses in the line are proportional to amps2, so the lower the current the better
Could it be dangerous to connect an alternator to a long transmission line if the line had a high capacitance?
Yes. Because... If we connect an alternator to a transmission line of high capacitance the line voltage will increase and caused a line voltage difference, which does not satisfied the condition of parallel operation of same voltage rating. [By Akhtaruzzaman08]
What are the function of the UPS?
Absorb relatively small power surges.Smooth out noisy power sources.Continue to provide power to equipment during line sags.Provide power for some time after a blackout has occurred.In addition, some UPS or UPS/software combination provide the following functions:Automatic shutdown of equipment during long power outages.Monitoring and logging of the status of the power supply.Display the Voltage/Current draw of the equipment.Restart equipment after a long power outage.Display the voltage currently on the line.Provide alarms on certain error conditions.Provide short circuit protection.
What does power line carry voltage or current?
It carries a current at the set voltage of the line. Current is the actual electricity that flows along the line and is used up in your electric appliances whereas voltage is the difference between the energy being generated at the station and ground.AnswerIt carries both voltage and current. Voltage exists between each line conductor, and current flows through each line conductor.
How many max transmission voltage in India?
There are three types of transmission lines of India given follows ---- 1-long transmission line( which is used grid to power suppliers plant ) 2-medium transmission line ( which is used power supplier plant to the industry ) 3- short transmission line ( which is used transformer to the consumers )
Why does the national grid use different voltages?
When transferring power over distance, the designer of the power line selects a voltage that optimizes the amount of power that is transferred, ie, minimizes the amount of power that is lost. There are tradeoffs in the selection of a voltage for a transmission line, as there are in almost any aspect of design. Too low a voltage (which requires a higher current) results in increased resistive losses in the lines, or you have to use heaver wire, which increases costs, not just of the wire, but of the stronger towers needed to support the wire. Too high a voltage leads to corona discharge losses and losses due to capacitance between lines and lines to ground. In addition, an AC voltage can be easily changed from one voltage to another with very small loss in power. So bottom line, each distribution line has a voltage selected to be optimum for that line. Connections between lines of different voltages are easily done via transformers.wire has inherent resistance. Power lost in this resistance is equivalent to P = I*I*R, where I is the current. Reducing the amount of current will reduce the inherent losses due to transporting power long distances. Power is equivalent to P = V*I; So, if we reduce the current, we must increase the voltage to maintain the same amount of power.Simply put, it is much more efficient. There is less loss transmitting the same amount of power down a line using high voltage rather than a lower voltage. Let's look and see why. Consider that the transmission lines have resistive properties (in ohms/foot). These represent a fixed loss; we can't get around them. We start with Ohm's Law: V=IR, and the definition of Power: P=VI. Substituting IR for V, we see that P=I²R. What this tells us is that the amount of power lost in the lines is equal to the square of the current flowing through the lines, times the resistance of the lines. The amount of power transmitted is constant, and the resistance in the lines is constant. So, if we double the voltage, the current is cut in half, and the losses are cut in quarter. The simple mathematics drives (dictates) that we use as high a voltage as is practical to transmit power over long lines to minimize the loss.
Can you get shocked from changing break light?
short answer: NO! most of the car's electrical systems like lights work with a maximum of 12V (battery voltage) which is a harmless voltage other than that the power is off anyway as long as you don't step on the break while changing the light (would be interesting how you would do that anyway ;-) )
