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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
How is the heat load of a transformer calculated?
Heat load is calculated by the following equation Q=m*cp*deltaT
m=mass flow rate
cp=specific heat
deltaT=difference in temperature
What difference between stabilizer and regulator?
in servo stabilizer voltage deviation is less(nearly+-1),in stabilizer it is +-10.The reason is in stabilizer there is only 3 or 4 out put based on input,but servo stabilizer works with servo motor therefor it will vary the out put with input through its movement over the transformer coils ,out put is taking from the contact portion of the servo motor with the generator coil.in stabilizer out put is taking from some intervals .
The total resistance in a series connection is equal to product of the individual resistance?
Yes. Power(P)=Current(I)xVoltage(E) or P=I x E, and since in a series circuit current is constant and voltage is additive then:
P(series)=Pr1+Pr2+Pr3........ Actually, power dissipated in series circuits is P = I^2 * R and in parallel power dissipated = V^2/R
When does current stop flowing in a circuit?
Current flows in a circuit when there is a difference in electronic potential between two points.
How do I convert ohm per square to ohm-cm?
You are trying to convert linear measurement to square, which is wrong. Conductivity is receprocial to resistivity; EC=1/ER the proper conversion is 1 Sm/cm=1 Ohm cm=100 Ohm m, but not Ohms per square.. Follow this link for discussion on the topic and for on-line calculators for converting electrical conductivity units. http://landviser.us/phpBB3/viewtopic.php?f=4&t=3
Which country use DC supply for domestic applications?
More over the rating only differs from country to country.No country employs DC current for domestic appliances because the voltage have to be stepped down or stepped up as per our requirement.
What is the relation between voltage and magnetic flux?
A magnet field is the area surrounding a magnet within which the effects of that field may be observed.
A magnetic field is represented by imaginary lines of force that we call magnetic flux. Magnetic flux (symbol, the Greek letter phi) is measured in webers (pronounced 'vay-bers'); the intensity of the magnetic flux is called magnetic flux density which is defined as the flux per unit area, measured in webers per square metre, which is given the special name, the tesla.
When does electrocution occur?
Common sources of electric shock muscle, nerve, tissue and skin injuries, or electrocution, are:
- lightning
- machinery
- electric cords
- electrical wiring
- electrical outlets
- electric appliances
- high-voltage power lines
Why Indian power system in multiples of 11kv?
Multiples of 11 kV are used in many countries. The idea is to deliver a round number of volts so you add on 10% to allow for line losses. So 10 kV becomes 11 kV. In practice lines are operated without a 10% voltage drop now because it represents an unacceptable waste of energy, but we have stuck with 11 kV etc.
Common supply voltages used for area distribution are 6.6 kV, 11 kV, 33 kV, 66 kV and 132 kV.
When a resistive AC circuit contains inductance the total opposition to current flow is called?
The resistance of an a.c. load is called 'resistance' (R). Resistance is not affected by frequency, only by the cross-sectional area, length, and resistivity of the conductor. Having said that, because of the skin effect, which causes an a.c. current to flow closer to the surface of the conductor, the effective cross-sectional are is reduced, so the value of a.c resistance is somewhat higher than the d.c. resistance -this difference increases with frequency.
The opposition to a.c due to inductive or capacitive loads is called reactance (inductive reactance or capacitive reactance), and the overall opposition to a.c. current is the vector sum of resistance and reactance, and is called impedance. That is:
(impedance)2 = (resistance)2 + (reactance)2
What are the causes of overheating of a dc motor?
a properly designed motor wont overheat unless it is overloaded
this is something like 3/4" drill with a 1/4" shaft that is used to drill in steel
sometimes hole saws have a 1/4" mandrel that will hold the entire line of saws
the motor must be matched to the load
When is steel used as an electrical conductor?
the main purpose of steel in acsr conductors is for mechanical strength
What is the purpose of individual units or component and how do they interact?
18. Component Description and application
Relay Relays are a special type of switch which is turned on and off by an electromagnet. When a current flows through the coil an electro-magnetic field is set up. The field attracts an iron armature, whose other end pushes the contacts together, completing the circuit. When the current is switched off, the contacts open again, switching the circuit off.
A useful property of relays is that the circuit powering the coil is completely separate from the circuit switched on by the relay. For this reason relays are often used where a safe low-voltage circuit is being used to control a high-voltage circuit.
Contactor A contactor is an electrically controlled switch used for switching a power circuit. A contactor is activated by a control input which is a lower voltage / current than that which the contactor is switching. Unlike general-purpose relays, contactors are designed to be directly connected to high-current load devices, not other control devices
Capacitor Capacitors store and discharge electrical current. They're made from 2 parallel metal plates separated by an insulator (dielectric) applications include;
Smoothing rectified alternating current voltages into steady direct current voltages
Blocking direct current signals whilst allowing alternating signals to pass
Filtering out unwanted portions of a fluctuating signal
Timing applications
Storing charge to keep a transistor turned on or off
Sensor A sensor is a type of transducer. There is a massive range of sensors Direct-indicating sensors, for example, a mercury thermometer, are human-readable. Other sensors, such as thermocouples, only produce an output voltage or other electrical output which must be interpreted by another device (such as a computer).
Resistor Resistors resist or 'slow down' the current in a circuit by acting against the flow of electrons.
hope this helps your NVQ work
Can you use a 60Hz variac in a 50 Hz outlet?
Yes, you can use a 60Hz variac in a 50 Hz outlet.
However, since the frequency is less, the current and power dissipation will be greater, making the efficiency less. It will not carry its rated load.
How do I adjust the rate of time on my hand winding watch?
Well it depends on what type of wrist watch it is ... if your has a few metallic buttons on the side maybe try to turn them different ways... :D
What are the M L C V terminals of a watt meter?
The M terminal connects to the power supply.
The L terminal connects to the load.
The C terminal is shorted to the M terminal.
The V terminal connects to the systems neutral.
What are the disadvantages of a brushless generator?
A brushless generator, in contrast, typically uses a solid-state rectifier assembly in place of the brushes and rings. This assembly contains no moving parts. This is important, as it makes the system more reliable and less prone to mechanical breakdown, jamming or seizing as a result of obstructions in the casing. Instead, a continuing charge is built up by transferring a portion of the generator's AC charge back into the exciter.
If ammeter 1 reads 2.A what will ammeter 2 read?
If an ammeter read 2A, another ammeter would probably also read 2A.
Keep in mind that every measurement involves error, and the equipment has a stated accuracy. If, for instance, the ammeter used had a 1% tolerance, than 2A actually means anywhere between 1.98A and 2.02A.
How do you prevent static hair?
when you wash your hair, rinse it with cold water before you get out! this helps it not be as dry and static. Also, try a leave in conditioner, or if youre just having a bad frizzy day, rub a light lotion between your hands and lightly rub through hair.
What is the voltage level of two phase machine in three phase?
From one phase to the next you should see 208 Volts.
From any phase to ground you should see 121 Volts.
AnswerYou are very unlikely to come across a two-phase machine, as two-phase a.c. systems are archaic. A two-phase system has two phase voltages that are 90 degrees out of phase with each other, and was used many years' ago. These days, you have either single phase or three phase. So it's probably safe to say that there are no two-phase motors about, these days!
The density of ductile cast iron is approximate 7.3 g/cubic centimeter, or 7.3 kg/liter.
The density of grey cast iron is approximate 7.2 - 7.4 g/cubic centimeter.
The density of cast steel is approximate 7.8 g/cubic centimeter.
The density of stainless steel is approximate 7.7 - 7.9 g/cubic centimeter.
The density of cast aluminum is approximate 2.6 g/cubic centimeter.
However, the density has a range of variation because of the material grades and shrinkage level.
So, you can see that cast iron is denser than cast aluminum, but cast steel is more denser.
For more information about the "density of ductile cast iron", you can refer to the article at the related links listed below.
What is the difference between Full load Amps and Service Factor Amps on an electric motor?
Full load amps is the amperage at which the motor was designed to work at to achieve its rated horsepower. Service factor amps is the amount of a periodic overload at which a motor can operate without overload or damage. Continuous operation within the service factor amps will shorten the insulation and motor bearing life of the motor as the motor will be operating at a higher temperature than it was designed to.
