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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
Usually a old fashioned locamotive is powered by a Steam/Coal Engine/furnace, but latest trains are powered by Diesil-Electric Engines, which changes the diesil power in the engine to electric and sends this energy to the wheels, consequently, making the wheels move.
Why governor are used in diesel generator?
Most modern petrol engines today are fitted with RPM limiters. Vehicles with automatic transmissions may not be in some cases, but the tranmission management software will shift the transmission before the engine over-revs, even if the driver selects a gear manually.
How the dc current shunt motor change from no load to full load efficiency?
decrease in starting and running torque and speed is almost constant from no load to full load. it's because the field voltage is consant and current is varied.
When a wire is amde smaller the resistance increase what happen to the electric current?
If a circuit existed where a wire could be made smaller AS the current from a defined source was applied to a defined user then in terms of amperage there would be little change in that parameter. In terms of the Power dissipated as heat through the electrical resistance of the wire then the wire would exhibit a marked increase in the heat expended (Power -watts= amperage- I x voltage -E) . With this in mind and using the same formula as noted the increase in P can only be attributed to an increase in E .To maintain the amperage -I. In short the smaller the wire the greater the voltage must be to maintain a set unit of amperage. In real world projects however the user raises wire size and does not modify voltage to maintain the amperage capacity. This is covered by the idea of calculation of voltage drop in a conductor based on its cross sectional area. From your question let me remind you that amperage is a function of usage and although stated on many devices does not exist until a circuit is closed ..Have a good one Edesigner.
What is copper losses in the motor?
'Copper loss' (I2R losses) is the generic term to describe energy losses that occur in any conductor (windings, in the case of transformers and other machines). The term applies, even when the conductors are manufactured from aluminium or other metals. The losses occur due to the temperature difference beween the conductor and the surrounds, causing heat transfer away from the conductor.
What is the importance of world systems theories?
World systems theories give a global perspective or construct of world events or processes captured for easy easy and systematic analysis. This can be liken to electrical power grid fed by generating units, transmission system and distribution beneficiaries, in local, regional and global contexts.
How can we produce 50 hz frequency ac current?
yes , we can convert it by a simple inverter . that's what every household inverter does.....
How do you correct power factor using capacitor bank?
Capacitor bank is use to control the power factor of the load, because there is many inductive load in the circuit which is the cause of the lagging P.F, so we use the capacitors to maintain the P.F to the unity, the capacitor have the nature of the leading P.F that's way the resultant P.F of the load's lagging and the capacitor's leading current is near to the unity, and the unity P.F has very good effect on the network.
What is voltage of TTL circuit?
CMOS gate circuits have input and output signal specifications that are quite different from TTL. For a CMOS gate operating at a power supply voltage of 5 volts, the acceptable input signal voltages range from 0 volts to 1.5 volts for a "low" logic state, and 3.5 volts to 5 volts for a "high" logic state. "Acceptable" output signal voltages (voltage levels guaranteed by the gate manufacturer over a specified range of load conditions) range from 0 volts to 0.05 volts for a "low" logic state, and 4.95 volts to 5 volts for a "high" logic state:
It should be obvious from these figures that CMOS gate circuits have far greater noise margins than TTL: 1.45 volts for CMOS low-level and high-level margins, versus a maximum of 0.7 volts for TTL. In other words, CMOS circuits can tolerate over twice the amount of superimposed "noise" voltage on their input lines before signal interpretation errors will result.
CMOS noise margins widen even further with higher operating voltages. Unlike TTL, which is restricted to a power supply voltage of 5 volts, CMOS may be powered by voltages as high as 15 volts (some CMOS circuits as high as 18 volts). Shown here are the acceptable "high" and "low" states, for both input and output, of CMOS integrated circuits operating at 10 volts and 15 volts, respectively:
The margins for acceptable "high" and "low" signals may be greater than what is shown in the previous illustrations. What is shown represents "worst-case" input signal performance, based on manufacturer's specifications. In practice, it may be found that a gate circuit will tolerate "high" signals of considerably less voltage and "low" signals of considerably greater voltage than those specified here.
Conversely, the extremely small output margins shown -- guaranteeing output states for "high" and "low" signals to within 0.05 volts of the power supply "rails" -- are optimistic. Such "solid" output voltage levels will be true only for conditions of minimum loading. If the gate is sourcing or sinking substantial current to a load, the output voltage will not be able to maintain these optimum levels, due to internal channel resistance of the gate's final output MOSFETs.
Within the "uncertain" range for any gate input, there will be some point of demarcation dividing the gate's actual "low" input signal range from its actual "high" input signal range. That is, somewhere between the lowest "high" signal voltage level and the highest "low" signal voltage level guaranteed by the gate manufacturer, there is a threshold voltage at which the gate willactuallyswitch its interpretation of a signal from "low" or "high" or vice versa. For most gate circuits, this unspecified voltage is a single point:
What will happen if you ground the grounded conductor or neutral at every device?
The ground wire is an important safety wire on an electrical appliance and to work properly it must not be one of the current-carrying wires.
That is because under fault conditions there could be transient spikes of voltage on the neutral wire, carried along the supply path, but the earth wire is earthed at the property so this is less likely.
Also in many cases the neutral is earthed at the supply transformer and there might be a small voltage between the neutral and earth in the house.
Wiring operations are very sensitive. Faulty wiring can cause overloads with service failures or even fires as the result. All wiring should be done by licensed professional tradespeople.
What is the principle of Resistance heating?
We understand diectric heating as the generation of thermal energy (heat) in a non-conducting material by the application of an electromagnetic force or field t it. This is the way a microwave oven heats things placed in it.
The microwaves (electromagnetic energy) cause water molecules, which are slightly polar, to "flip" back and forth in an attempt to align themselves with the magnetic field of the microwave energy. The "flipping" or "ringing" of these molecules created thermal energy in them, and this is transferred throughout whatever is inside the oven cavity when it's on. The result is that stuff gets hot, which is why we put it in there.
Well, it is certainly not a globe with just electrons glowing inside it!
The globe contains a very hot ionized gas, which is known as a plasma.
A plasma is defined as:
An electrically neutral, highly ionized gas composed of ions, electrons, and neutral particles. It is a phase of matter distinct from solids, liquids, and normal gases.
What happens if i use a 12v Dc in a device that requires 9v DC And can it be repaired?
Not a good idea. It will raise the current that could burn out components. To repair you would need to determine what was burned out and how easy it would be to replace.
Will transformer heating the same for resisitve inductive and capacitive loads of same va rating?
Yes, transformer losses will be the same for any linear load with the same VA. However, if the load is nonlinear, such as a rectifier, the load waveform will be distorted and the losses will be higher than with an undistorted sinusoidal load current of the same VA
What will be the size of cable for 75 HP 220 Volts 3 phase motor?
75 HP = 55 KW
55 = 31/2 x 0.220 x I x cos φ = 31/2 x 0.220 x 0.8 x I
I = 55/(31/2 x 0.220 x 0.8) = 180,42 A
3 x 70 mm2 is the size of cable for 75 HP 220 Volts 3 phase motor
What is the relation between carrier frequency and modulating signal?
If the modulating system is AM (Amplitude Modulation) then the amplitude of the carrier wave changes with the amplitude of the modulation. On a specrum analyser that shows up as frequency sidebands. If the frequency of the carrier waves depends on the amplitude of the modulating signal that is called FM (frequency modulation). On a spectrum analyser that shows up as sidebands also.
Why parallel circuits are used for house lights?
bcz when we connect the circuit in series then- -the voltage divides, therefore all the appliances do not wrk properly -in series if one appliance is switched off then all the other appliances also gets switched off i.e.u should have diff. switch off n on key.. this is d reason y we prefer parallel connection so that if 1 appliance doesn't wrk properly then all the connections do not get affectd
What is the power equation for three phase line?
Power is the line voltage times the current times sqrt(3). The answer is in VA. Example 33 kV 400 amps, 22.8 MVA.
How to check 220-240 volt single phase capacitor start motor if it will not start?
I'm assuming you want to check to see if the motor works.
In other words, if the motor isn't working you want to know if the motor is bad or the capacitor is bad.
Turn on power to the motor, and carefully attempt to start motor rotation in the correct direction by manually rotating the shaft or the load connected to the shaft.
If the motor will maintain its motion once you get it started, the problem is most likely a capacitor. Check the capacitors for bulging and replace any defective parts.
If the motor will not spin at all, or will not maintain any momentum, the motor is likely the problem. You can replace it or try to reduce the rotating friction by lubricating the bearings, etc.
IF YOU'RE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
If you do this work yourself, always turn off the powerat the breaker box/fuse panel BEFORE you attempt to do any work AND always use a meter or voltage indicator to insure the circuit is, in fact, de-energized.
Can you get a 3 phase supply from single phase and how?
No, you cannot get a three phase supply directly from a single phase supply.
Nowadays electronic inverter units can be bought that will do the job. For very low power loads the cost of such invertors is quite reasonable but for high power loads they are very expensive.
For high-power industrial uses the most economical solution is to have a 3-phase service installed by the local electric power utility company.
What are the advantages of three phase induction motors over the other motors?
A Single phase induction motor includes a main winding, an auxiliary winding, a run capacitor, & a subsidiary star device. The auxiliary winding is configured such that the number of turns of the aauxiliary winding through which a current flows, varies according to the operating mode of motor. When the motor starts, the number of turns of the auxiliary winding through which a current flows is reduced there by increasing the start efficiency of the motor. when the motor runs in normal mode, the number of turns of auxiliary winding through which a current flows is increasing there by increasing the operations efficiency of motor
What is the peak voltage of a 120 vac supply?
"It is about 170 volt." was the given answer to this question.
Incorrect. This would be the correct answer if question were "What is the 0-to-peak voltage of a 120 volt AC circuit?" The "120" represents the root-mean-square (rms) value of the voltage. To get the peak value of the sine wave for any such rms figure, you multiply the rms figure by the square root of 2 (~1.41), i.e. 120 x 1.41 = 170.
The PEAK-TO-PEAK voltage of the sine wave is simply twice the 0-to-peak value. Hence, the correct answer, for PEAK-TO-PEAK, is 170 x 2 = 340 volts.
So, the correct answer to the question is 340 volts.
What is 1 mega ohm equal to in kilo volts?
Ohms and volts are different things -- it's not possible to equate ohms to volts.
