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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
Does a short circuit damage your battery?
Yes it does. A short circuited battery creates excessive heat from the rapid discharge. This heat damages the internal chemicals and component materials in the battery. In some cases can even cause explosions and fire.
Why transformer not obey ohms law?
A: Ohms law apply to any and to all components if there is current flowing.
Answer
For Ohm's Law to apply, the ratio of voltage to current must remain constant for variations in voltage. This is only true for a limited range of conductors and devices which are termed 'linear' or 'ohmic'. If the ratio of voltage to current changes for variations in voltage, then the conductor or device is 'non-linear' or 'non-ohmic', and Ohm's Law does NOT apply. An example of a non-ohmic conductor is tungsten (e.g. a lamp filament) and an example of a non-linear device is a diode -there are many more.
As to whether a transformer obeys Ohm's Law, the answer is not straightforward. When the transformer is not supplying a load, the primary current is determined by the voltage and impedance of the primary windings and, say, doubling the voltage will double the primary current -so you could say that it is obeying Ohm's Law. However, when the transformer is supplying load, the primary current is determined by the secondary current and not just by variations in the supply voltage, so is clearly not obeying Ohm's Law.
Distinguish between accuracy and precision of a measurement?
Measurements are precise when they are all very similar (ie, if a temperature was measured as 23.2C, 23.1C, and 23.3C). Measurements are accurate when they are close to a known value (such as 100.01C measured as the boiling point of pure water at 1 atm).
You will have trouble plugging a 220 volt appliance into a 110 volt outlet because both have different polarities for the plug and receptacle that make it impossible for that action to happen.
Altering the plug isn't too good of an idea, as the voltage demand of the appliance would be too heavy for the wiring.
Why current leading in capactor?
In the ac waveform of a capacitor the current waveform leads the voltage waveform
current is large to start until capacitor fills with it's voltage charge if that helps
AnswerThe terms 'leading' and 'lagging', used when describing power factor, are defined in terms of whether the load current is leading or lagging the supply voltage.
In a capacitive circuit, the load current leads the supply voltage, so the power factor is leading.
What will happen if you change Phase and neutral connection to single phase motor?
Most likely is going to explode. Put 120 psi on a car tire rated for 35psi and you will have the same effect.
Answer
The circuit's protective device will disconnect the motor from the supply, It will not explode!
What happens in a winding house of a mine?
The winding house houses the engine that raises and lowers the mine's cage (lift).
its creates the magnetic field trough the electricity,which we called exciter for it.we send some electric shocks to the field coils,then it will magnetized the stater of the generator. When Diesel or petrol engine rotates the rotter of the generator, EXCITED stater act as a magnet. Depend on alternator`s design,rotter or stater one always EXITED to be a magnet. When engine turns the Alternator against the magnetic field,electricity is produced.
What is the average wall thickness?
5-6"
The average wall is a constructed 2x4 stud wall with a layer of Sheetrock on top of that. As can be found on the Internet, a 2x4 is actually 1.5" x 3.5" And a piece of Sheetrock is .75" So .75+.75+3.5= 5"
An exterior wall is thicker due to the different materials used in the construction. It is also has a 2x4 stud wall framing with a layer of 3/4" OSB(Oriented Strand Board) or Plywood with a layer of plastic (negligible thickness) and the exterior material on top of that. Other Variations include various foams and insulation layers.
What would result from increasing the resistance in a series circuit with one resistance (load)?
Resistance increases what happens to amperage?
yes
AnswerNo! Resistance is determined by the length, cross-sectional area, and resistivity of a conductor. Resistivity is, in turn, affected by temperature -so temperature indirectly affects resistance.
These are the only factors that affect resistance. Voltage and current have no direct effect whatsoever on resistance. Current can affect resistance indirectly if it causes the conductor's temperature to increase.
For AC circuits, 'skin effect', due to frequency, causes the current to flow towards the surface of a conductor which acts to reduce the effective cross-sectional area of that conductor. So, frequency can also indirectly affect resistance.
How do you connect a generator to your home?
There are several ways. The safest is to have an electrician install a transfer switch. This allows you to connect a portable generator to its 4 prong outlet and prevents city power from entering the house and generator. You basically have a manual switch to decide if you want generator power or city. Its a safety thing. This will cost you at least $300 in parts plus the electrician.
There is also an cheaper alternative to a manual transfer switch. There definitely needs to be a safety device but a manual transfer switch is difficult and expensive to install plus it takes a good electrician to make a professional job. An interlocking device, such as the ones from interlockkit.com, mounts on the front of your panel and keeps the main breaker and the generator from being on at the same time. This ensures that the line physically cant be back-fed, which keeps lineman from being shocked and killed. It only takes an hour or so to do the whole job and meets electrical code.
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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
What is the importance of the voltage regulation?
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What is an acceptable difference in resistance between phases on a 3 phase motor?
The currents between legs of a three phase circuit should be within about 10% of each other.
What Created around a conductor when electrons flow through that conductor?
Whenever a charge passes through a conductor, a magnetic field is produced. Hence, whenever a current carrying conductor is placed in a magnetic filed, it will experience a force whose direction is determined by Fleming's left hand rule.
What is the watts required for a 250HP 3 phase 480 motor?
The power consumption of the motor cannot be determined without more information. The power consumption of any load can be determined with any two of three interrelated parameters--voltage, current, or load impedance. (Ohm's Law)
If AC Current changes direction 120 times per second so how many cycles is that?
Each cycle includes two changes of direction.
120 changes of direction per second = (120 / 2) = 60 cycles per second = 60 Hz.
How many amps does a 3 phase 20 hp motor use?
30 HP at 480 (3 Phase) - 746 multiplied by 30 = 22380
22380 divided by 480 (3 Phase) = 46.5
46.5 divided by 1.73 = 29.5AMPS
Motor speed and efficiency may change the actual result. Always refer to the name plate data
What is produced by a generator?
The general term generator is usually applied to the kind of generator that produces electricity, or electric power.
Can you substitute 12V. AC 40va Transformer for 12V. AC 1000ma. Home service-out door fountain?
Yes, the output current of a 40va transformer at 12 volts is 3.33 amps. The replaced unit had an output of 1 amp making it a 12va transformer. By doing this exchange there will be three times the capacity of the new transformer over the old transformer.
In what situation would a 3 phase converter be used?
Three phase converters are used in electrical power distribution systems. Electricity gets sent out in cycles and waves. A three phase system allows electric currents to be time delayed according to the waves, so that power appears to be continuous. Converters are used by small clients who cannot afford direct access to a three phase grid, but still want to localize their power source - such as small residences, farmers, or some train operators.
What is the difference between star delta and wye delta?
With a delta connection, picture a triangle. Each side of the triangle is a transformer or motor winding. Call the 3 corners of the triangle A, B, and C. There are only 3 wires except for a safety ground, which has no connection to, nor is any part of, the power transmission service lines.but for the star connection take our triangle above and use your wire cutters (literally) to cut the triangle apart at the corners. rearrange the three sides (transformer or motor windings) to form a Y. Where the three sides join in the centre, connect a fourth wire. Call this wire "neutral". Call the three ends A, B, and C. Connect the 3 supply service lines to A, B, and C.
Work it out yourself -the equation is: voltage = current x resistance.
