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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 much power does a 300 VA UPS consume?
From the description given its output power would be 300 Volt-Amps which is almost the same as 300 Watts but may not be, depending on the power factor.
If we allow, say, 10% extra for power losses, the UPS (Un-interruptable Power Supply to those who don't know what such things are) may consume about 330 Watts from your building's main electrical power supply.
If you need to have a more accurate idea of the power it takes why not look at the rating plate on the UPS unit itself? Or if you had a Wattmeter you could measure the maximum power drawn when it is working at full load charging its batteries.
Safety precaution in using fuel?
There are several safety precautions that should be used when working around fuels. Specifically, always turn the car off when fueling up. Additionally, if a fire breaks out while using a petrol pump, do not worry about removing the nozzle, just get away from the fire and get help.
Since they are in series you can use R=R1+R2+R3... for Total Resistance, then use Ohms Law of I=V/R and solve for I and R. (remember that V and I are also Totals, unless you brake them down at each point)
What is the concept of the kelvin bridge circuit?
Kelvin Bridge: This Bridge is a modified version of Wheatstone Bridge and provides greatly increased accuracy in the measurement of low value resistances, generally below 1 ohm.
Applications of wien bridge oscillator?
A Wein Bridge Oscillator is a oscillator which is used for the measurement of Audio Frequency.
Can you cut plastic with plasma cutter?
No, you can't cut plastic with a plasma cutter. Often times the heat is so high that it will just cause the plastic to melt.
What is electrical impendance?
Impedance (Z) is the vector sum of a circuit's resistance (R) and reactance(X), is expressed in ohms, and is the total opposition to current in an a.c. circuit.
Resistance, expressed in ohms, depends upon the length, cross-sectional area, and resistivity of the conductor.
Reactance, expressed in ohms, can be inductive reactance (XL), capacitive reactance(XC), or a combination (vector sum) of the two.
- Inductive reactance is directly proportional to the circuit's inductance and the supply frequency.
- Capacitive reactance is inversely proportional to the circuit's capacitance and the supply frequency.
What is the symbol for a light bulb?
a circle with a cross through it a circle with a cross through it
Here we are given 3.1 amperes of current and are asked to find the time it takes 10 coulombs of charge to pass a given point. First ask yourself how many coulombs are passing a given point in one second. If we have 3.1 amperes of current, we have 3.1 coulombs of charge passing any given point in one second. If it takes 1 second for 3.1 coulombs of charge to pass, how long will it take for 10C of charge to pass?
Why are all cores exposed to ac flux variation laminated?
Limit effects (heat loss) caused by eddy currents
The stator coil is exactly the same as a 3 phase induction motor. The difference being the rotar which has 3 phase wiring in star point or delta connection and also has the sliprings connected to the wiring of the rotor. Brushes are use for the contact between the surpply and the rotor. By controling the current we can control the torgue and speed of the motor. This is done with resistance. Resistance can be greated by means of a resistance bank, liquid resistance or a variable resistance. The basic Idee is: The higher the resistance, low starting current, high torque, high % slip. Motor runs slowly
Low resistance , Higher starting current, lower torgue, lower % slip Motor runs faster.
Thus by varing the rotor resistance the motor can be adapted for a spesific load.
The motor Are mainly used for Overhead cranes, Elevators in buldings, Pumps under pressure and large fans
What is meant by single line diagram?
Single sine diagram is graphical representation of electrical circuit drawn using single line instead of drawing 3 separate lines for three phases.
What are advantages of electronic wattmeter?
The advantages of wattmeter include adequate for low frequencies, easy to operate and better technology. There are different types of wattmeter and each has specific advantages.
What is the demand for engineers?
Job Outlook
Employment of engineers is expected to grow about as fast as the average for all occupations over the next decade, but growth will vary by specialty. Environmental engineers should experience the fastest growth, while civil engineers should see the largest employment increase. Overall job opportunities in engineering are expected to be good.
Overall employment change. Overall engineering employment is expected to grow by 11 percent over the 2006-16 decade, about as fast as the average for all occupations. Engineers have traditionally been concentrated in slower growing or declining manufacturing industries, in which they will continue to be needed to design, build, test, and improve manufactured products. However, increasing employment of engineers in faster growing service industries should generate most of the employment growth. Job outlook varies by engineering specialty.
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How field current change in 'V and inverted v curves ' of synchronous motor?
In v curves armature current decreases in under excitation and increase in overexcitation as fielcurrent increases and armature current is maximum at unity power factor.The power is maximum when load angle is equal to impedance angle.A linear motor is a essentially a multi phase
Why does voltage lead current in an inductor?
From what I've read, an inductor is designed to store energy in the form of a magnetic flux. A simple inductor can be thought of as a coil of wires around a medium. The current causes the flux to go through each turn of the coil. Further examination and Faraday's law leads to this model.
v= N * D(magnetic flux)
Because the current inside the coil is what generates the flux, the voltage will change first, before the flowing electrons will get all the way through the inductor.
The inductance constant L is the Number of turns in the wire times the ratio of the current i to the magnetic flux, which is usually a constant.
L = N*flux/i
Which leads to this relationship between voltage and current in an inductor:
v = L* D(i)
The D() function being a derivative. Because the derivative of the current will change before the current actually does, voltage leads current in an inductor.
What is National Electric Code Article 250?
The national electrical code is a publication thet governs commercial, residential and industrial electrical installations. Article 250 is the section governing grounding and bonding installations.
Why cooling of a transformer is necessary?
TO INCREASE END-OF-LIFE EXPECTANCY OF THE UNIT AND MAXIMIZE CAPACITY AND TO HANDLE OVERLOAD UP TO 40%.
Why are transmission voltages in multiples of 11?
Transmission voltages are in multiples of 11 to allow for 10% transmission line losses. Therefore, to obtain 100% efficiency, voltages in multiples of 11 are transmitted.
A binary encoder is a person who creates a code used to program computers at the most basic level. Claude Shanna developed binary encoding in the 1930s.
