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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
Can you connect 480 volt 3 phase WYE POWER to a 3 phase 480 volt delta primary transformer?
Probably not, in the case of a three-phase transformer as it has been pre-connected, enclosed in a metal tank, fitted with the appropriate bushings, etc.. However, it is a relatively straightforward job in the case of a three-phase transformer bank that comprises three separate, single-phase, transformers.
Whether you'll obtain your desired secondary voltage is another matter.
The 'one wattmeter method' can only be used for balanced, wye-connected, loads where the load's neutral point is accessible. The wattmeter's current coil is inserted into any line conductor, and the voltage coil is connected between the same line and the neutral point. The wattmeter reading indicates the power of one phase, so the total power is three times the wattmeter reading.
To measure the total power of a balanced or unbalanced wye- or delta-connected load, it is only necessary to use twowattmeters -this is called the 'two wattmeter method'. In this case, the current coils of each wattmeter are inserted into any two line conductors, and the voltage coils are connected between the two line conductors and the third line conductor. The sum of the two wattmeter readings will indicate the total power of the load.
The consumer price index is a measure of?
Compiled by the Bureau of Labor Statistics, the CPI measures the rate of inflation from month to month. It reports the price of a "market basket," a collection of around 300 goods that a typical consumer buys regularly. It then measures the increase or decrease of that price from the price in a given year. If the CPI for 2010 were 180, then prices have risen about 80% from the base year.
Core CPI does not take into account oil and food prices, which are more volatile. As a result, many economists prefer to use Core CPI when measuring long-term inflation.
How do you convert 12 volts dc to 3 volts dc for LED?
Depends on the led forward bias threashold, if its a typical led it will be .7 volts so, .7x6=4.2V, so pick a resistor that will drop around 7 volts. What is the current? Then just to V=IR, 7=IR.
What is the effect of diode voltage drop as the output voltage?
The effect of diode voltage drop as the output voltage is that the input voltage will not be totally transferred to the output because power loss in the diode .
The output voltage will then be given by:
vout=(vin)-(the diode voltage drop).
How inductance is produced when electric current passes through a conductor?
Electric charges interact with changing magnetic fields. All magnetic field changes can be thought of as the magnetic field moving. If the magnetic field strength is increasing then it is the same as a magnet being brought nearer while a decreasing magnetic field is the same as if a magnet is being pulled away.
The force a charge experiences is the result of several factors. The direction of the force depends on the polarity of the charge, whether it is positive or negative, the direction of the magnetic field and the direction of relative motion between the charge and magnetic field. The magnitude of the force, its strength, depends upon the amount of charge, the strength of the magnetic field and the speed of the relative motion between them.
So you can make charges inside a piece of wire move by waving a magnet near the wire. If the wire makes a circuit, then you get electric current flowing through that circuit. A generator is a device which uses the interaction between charges and changing magnetic fields to create electric current. Generators require a source of mechanical energy to run. Portable generators typically use gasoline while generators used by the electric power company can be driven by water, wind, coal, natural gas or the heat from nuclear fission. Coal is the most common source of energy for electricity in the United States.
How can the output voltage of a DC generator's polarity be reversed?
The polarity of DC generator can be reversed by reversing the field current as well as direction of rotation
How do you make a 380v motor run on 220v?
Yes just connect any line to neutral you have 230volts already.
In order to send more than one bit at a time during a single phase on a carrier modulation is used?
amplitude modulation is used
How can calculate the current of 3 resistors wired in parallel?
In this case, to get the equivalent resistance, first you use the parallel formula (1/R = 1/R1 + 1/R2) to calculate the equivalent resistors in parallel. Then you calculate the series resistance of this combination, with the other resistor.
Does a standard multimeter measure ac in peak or peak to peak?
Neither. A.C. voltage, and current, are expressed as root-mean-square (rms) values, and this is what a voltmeter and an ammeter reading will indicate. To measure peak voltage, or peak-to-peak voltage, you will need to use an oscilloscope.
How much resistance is in the circuit if it uses a current of 10ma?
Just use Ohms Law: V=IR, that is, voltage (in Volt) = current (in Ampere) x resistance (in Ohms).
Explain the term corona in transmission line.?
At very high voltages, corona becomes an issue, such as in high power transmission. In effect, if there are any "sharp points", square corners, etc., electrons will tend to build up and this build up begins to damage the structure. this is why in very high voltage subs, you will see rings used instead of bolts or hooks (easiest to see at the top of poles).
What are the disadvantages in using a series circuit?
Series:
It is impossible to control the bulbs individually. This is one reason that series circuits are not practical for use in home lighting: It is not possible to control the lights in different rooms throughout the house on the same circuit. For example, if someone wanted to read the newspaper or watch television, he would have to turn on a switch that would put on every light and electrical appliance in the whole house.
Also, in a series circuit, the more output devices you add the slower the current becomes. If these output devices were, for example, bulbs, this would mean that the brightness of the bulbs would be dimmed. Another disadvantage of a series circuit is that if a bulb were broken or the pathway broken in any way, the other bulbs would go out too.
Advantages are that you can add more power sources, like batteries, and increase the force of the output which grants you more power. In Parallel, however, the power stays at the same voltage of the original power source. For example, if you were running a circuit on a 5-volt battery and it kept the bulb going for two hours and then added another 5-volt battery, it would keep the bulbs going for four hours instead, but it would only give out 5-volts instead of increasing it to ten.
Parallel:
Advantages would be that, if it were light bulbs that were the output devices linked in parallel, if one bulb broke the others would continue going. Also, the brightness of the bulbs would be greater than the brightness of bulbs in series.
Disadvantages are that there could be a risk of fire in some cases. Another would be that, if you have multiple power sources, the power stays at the same voltage as that of the single power source. In parallel, increasing the number of output devices does not increase the resistance like it does in series.
What is hi-pot test in mv cables?
with a voltage source and a current meter and log log paper.
(hi-pot tester)
plot the voltage vs the current
when the line starts to bend or knee you are close to the failure voltage
How do you do staircase wiring?
A two way switch is required for staircase wiring. A staircase switch will have two terminals. Connect the line wire with the center terminal. Connect the two ends of a wire with the top two terminals and two ends of a wire with the bottom two terminals. The line wire at the center terminal can now be connected with one terminal of the light bulb or light holder.
Does adding an extra light bulb in a circuit increases its resistance?
If the bulbs are in parallel, other bulbs aren't affected, so I guess you mean a series circuit.
A string of light bulbs connected in series (like a Christmas light string) connected to a specific supply voltage can be visualised as a string of rubber bands, knotted to each other in a line, and stretched to a specific distance.
If all the rubber bands are the same, they will all stretch equally, i.e. if all bulbs are the same, they will all have the same voltage across them.
Increasing the resistance of one bulb is like making one rubber band thinner than the others, and you can imagine what will happen.
The thin rubber band will stretch more than the others, and the others will take up the slack and become a bit shorter, i.e. the bulb with higher resistance will have more voltage across it, and the remaining bulbs will have slightly less than before.
The current (i.e. the tension in the string of rubber bands) reduces slightly.
Looking at the power dissipation for that light bulb, which is voltage x current, voltage will increase, and current will drop slightly, so the overall effect is that the bulb with the higher resistance will dissipate more power than the others.
Why internal resistance of an ideal voltage source is zero and an ideal current source is infinty?
Current source means current generator for a circuit.
An ideal current source gives all current to the circuit, but practically a current source does n't give all current to the circuit, instead, a source resistor is connected in parallel to the current source to indicate the current drop.
How do you step down 240V ac to 220V ac?
You can use a voltage transformer or converter that is specifically designed to step down the voltage from 240V AC to 220V AC. Make sure to select a transformer that is rated for the appropriate power handling capacity to ensure safe and efficient operation.
It is not advisable to do so. You may burn the winding, insulation may fail.
How many volts does the average AC power generator make?
This depends on what you are meaning by "Average".
A typical small generator you can throw in the back of a truck will produce 120 volts, some can do 240.
Building backup generators would produce whatever voltage is needed for that building (if it's a plant that using 480 volts, it will produce 480 volts).
"Large" Wind turbine generators often produce 600-1000 volts; good sized power plants (100MW and up) will typically have a terminal voltage of 10-30kV.
How much current must flow to carry 240 watts at 120 volts?
240 watts at 120 volts requires 2 amperes.
Power = voltage * current
How many ohm's is a 1M5 resistor?
The plural of 'ohm' is ohms, not ohm's.
The alpha-numeric code for identifying the resistance of a resistor is quite straightforward.
The letter is used as a multiplier. For example, k= x1000 and M = x1000 000. In other words, k represents kilo, and M represents mega.
The position of the letter represents the position of the decimal marker.
So,
- 1M5 represents 1.5 x 1000 000, or 1.5 megohms.
- 15M represents 15 x 1000 000, or 15 megohms.
- etc.
Similarly,
- 1k5 represents 1.5 x 1000, or 1.5 kilohms.
- 15k represents 15 x 1000, or 15 kilohms.
- etc.
A capacitor opposes a change in?
Capacitors charge by transferring charge from one plate to the other. This is not the same as a battery, though it can seem so. They oppose a change in voltage because the two plates are close to each other, separated by the dielectric, and the transfer of charge requires current. Once charged, however, the current becomes zero. The differential equation describing a capacitor is dv/dt = i/c, or volts per second = current over capacitance.
