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Because higher voltage can carry further.
That answer is too simplistic. The actual reason is as follows: for any given load, the higher the supply voltage, the lower the resulting current. Lower currents mean smaller diameter transmission/distribution conductors can be used and the line losses(I2R) are lower.
Wiki User
∙ 13y ago
Wiki User
∙ 13y agoHigh currents give off a lot of heat. This means a lot of useful energy is lost through useless heat. This makes it inefficient. Transformers are used to step up and step down the voltages coming out of the power stations and into homes.
To get the lowest loss of power in a particular distribution line, you want to be able to use the lowest current that is economically possible. So, to get a low current, you need to transmit the energy at the highest voltage that is economically possible for that particular line. That is why a transformer is used to step up the voltage for long-distance transmission along the line. Another transformer must be used at the other end of the line to step the voltage down again for use at lower, safer, voltages in homes, offices, factories, etc.
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If the resistance in a circuit is doubled while the voltage remains the constant the current is?
It is halved. coz voltage=current * resistance
Why high voltage is kept open in open circuit and low voltage is shorted in short circuit test?
In Short circuit test High Voltage side is feeded with 2-5% of the High Voltage rating to circulate approximately full load current in low voltage winding by short circuiting it. Low voltage is generally short circuited to facilitate measurements because it is more difficult to measure the quantities at high voltages.
What happens to electric current as voltage gets large?
If the resistance of the load is kept more-or-less constant, then the current also becomes larger. On the other hand, if the power of the load is kept more-or-less constant, then the current becomes smaller.
Why in summers voltage coming is less in houses?
This is commonly a problem called "voltage drop". Simply, if you have any power supplying unit connected to an electrical load, it draws an amount of electrical current based on the load value. The voltage at the supply terminals is higher than on the load terminals, this is due to the resistance (impedance) of the connection wires (cables). The more the connection resistance (more resistance means less cross-sectional area), the less the load voltage (if source voltage and load current are kept constants). Another thing that affects the load voltage, is the load current itself. If the load current increases, the load voltage decreases (if source voltage and connection resistance are kept constants). This means that any load current or connection resistance increase mean that the load voltage will decrease. This is exactly what happens in summer. In summer the ambient air temperature is high and hence all connection network elements (wires, cables, TL...) have higher resistance. Plus, most of the air conditioning units operate in summer (higher load current) which represent a bulk load to the network.
Why is the voltage increased and decreased at various places during distribution?
Power in a line remains constant when you pass it through a transformer. P = V*I. When V goes up, I goes down. When you want to distribute electricity, the resistance of the wire carrying it causes losses, following the equation P loss = I^2*R. So you can see that having a very high voltage causes a very low current, which results in lower power losses. The reason the voltage is not kept that high at all times is it is unsafe to have voltage at the level in people's houses. The higher the voltage is, the farther it is able is able to arc across the air and cause shorts.
Why do secondaries kept short in current transformer?
To prevent the appearance of a dangerously-high secondary voltage across its terminals.
Why are power lines that move high voltage tall?
Because the line conductors are uninsulated, and must be kept at a safe distance above ground level.
If the resistance in a circuit is doubled while the voltage remains the constant the current is?
It is halved. coz voltage=current * resistance
Why high voltage is kept open in open circuit and low voltage is shorted in short circuit test?
In Short circuit test High Voltage side is feeded with 2-5% of the High Voltage rating to circulate approximately full load current in low voltage winding by short circuiting it. Low voltage is generally short circuited to facilitate measurements because it is more difficult to measure the quantities at high voltages.
Why are high voltage poles are kept above ground?
A couple of reasons I can think of include: High voltage overhead cable is much cheaper than underground cable Easier to reconductor (upgrade current carrying capacity) Easier to find faults
What is the relationship between the voltage and the current when the resistance is kept constant?
Ohm's Law: voltage = current * resistance. If resistance is a constant, then voltage is directly proportional to current.
Will decreasing the resistance in a circuit decrease current flow if voltage is kept constant?
You should answer this question yourself by doing a couple of examples using Ohm's law I=E/R (current equals voltage divided by resistance. Here they are: Base circuit: 10 volt supply feeding a 10 ohm resistor calculate the current... New circuit: 10 volt supply (voltage kept constant) feeding a 20 ohm resistor (increased resistance) calculate the current... Did the current increase, or decrease? This way you can prove to yourself the answer!
What happens to electric current as voltage gets large?
If the resistance of the load is kept more-or-less constant, then the current also becomes larger. On the other hand, if the power of the load is kept more-or-less constant, then the current becomes smaller.
How does a current transformer work?
A current transformer is used in high voltage circuits where it is not possible to measure current directly. A CT is a step up transformer with only one turn in primary. There will be as many cores based on the purposes like metering, protection etc. The secondary of a CT should never be kept open circuited bcoz very high flux will be developed in the secondary and hence it may be damaged.
What happens to the current in a circuit if the voltage is increased?
What are the changes to the resistance and the voltage will always increase the current in a circuit
Why in summers voltage coming is less in houses?
This is commonly a problem called "voltage drop". Simply, if you have any power supplying unit connected to an electrical load, it draws an amount of electrical current based on the load value. The voltage at the supply terminals is higher than on the load terminals, this is due to the resistance (impedance) of the connection wires (cables). The more the connection resistance (more resistance means less cross-sectional area), the less the load voltage (if source voltage and load current are kept constants). Another thing that affects the load voltage, is the load current itself. If the load current increases, the load voltage decreases (if source voltage and connection resistance are kept constants). This means that any load current or connection resistance increase mean that the load voltage will decrease. This is exactly what happens in summer. In summer the ambient air temperature is high and hence all connection network elements (wires, cables, TL...) have higher resistance. Plus, most of the air conditioning units operate in summer (higher load current) which represent a bulk load to the network.
Why open circuit test is performed on low voltage side?
generally open circuit test is performed on the low voltage side.....not on high voltage side.... becuase on low voltage side, we can apply that low voltage very easily ( i.e with a less amount of source is required)... whereas on high voltage side, we need a large power source in order to apply full voltage... in short circuit test, we will test on high voltage side by keeping Low voltage side being short circuit.because high voltage side needs less current source than low voltage side....
