0
Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
Why conductors are designed using smaller strands?
Two reasons:
- Mostly a stranded wire is far more flexible than a solid one and less likely to break after repeated flexing.
- At AC frequencies in the RF range an effect called the "skin effect" starts to become significant, current flow restricts itself to the skin of the conductor and the wire resistance rises. Stranded wire offers more skin and thus reduces the wire resistance again.
How do you measure the capacitance of 3 phase capacitor in active line voltage of 3 phase circuit?
You measure the capacitance of a capacitor in an active circuit by observing the voltage across it and the current through it. That gives you, by Ohm's law, the impedance of the capacitor. Plug that in the the equation for capacitive reactance, and you get capacitance.
Note: There is no such thing as a three phase capacitor. A capacitor is a two terminal device that resists a change in voltage inversely proportional to its capacitance. You connect one capacitor to one phase. If you have a "three phase capacitor", then you are talking about three capacitors. Deal with each one separately.
Why do you need varnish in transformers?
A: The iron on a typical transformer is made up by adding iron leaves to the core. These leaves will vibrate if held loosely by a screw which add to eddy current. to stop the vibration varnish is applied to keep the leaves of iron coherent
The AC voltage is in the form of a sine wave. Half the wave is above zero volts and half below. In half wave rectification the bottom half of the wave is chopped off. That leaves a series of "humps' interspersed with a half wave time of zero voltage. The capacitor stores charge that decays through the resistor. The more capacitance the longer the charge is held and the voltage smooths out somewhat to approximate a DC voltage with some ripple. A full wave rectifier flips the bottom half of the waveform above zero so that the period of time the voltage is close to zero is reduced and the less ripple in the output voltage and the capacitor will smooth out the voltage even more.
Why ammeter is always connected in series to electrical circuit?
the power needs to go "through" the ammeter for it to accurately measure the amount of amps being used. unlike a volt gauge that just measures what the system has for voltage. volts and amps are totally different.
What does brown-out protection mean?
I am no expert at all, but it is like the opposite of power-surge. So the electrical power is reduced which may mean that your electrical devices and appliances may be damaged if a brown-out occurs. It is also related to a 'black-out' when all power is lost (black-outs are safer for your electronics and appliances because mostly it is just like turning them off at the wall socket).
You should have a power protection board that protects you from brown-outs (low voltage) and power-surge (high voltage).
Why the stator is not laminated in DC machines?
The stator is not laminated in DC machines because it does not need to be laminated.
Lamination is used in AC machines to prevent eddy currents from generating excess power due to the transformer effect of having a one-turn secondary that is short circuited. There is more to it than just the laminations - the laminations are insulated from each other, and interleaved, so that they have poor electrical connection while having good magnetic coupling.
What is Conventional Earthing?
The conventional earth is the use of a copper rod and plate driven into the earth.
In dry areas this may be not sufficient to make a good earth and chemical systems are available. Chemical earths use a more resistant material to copper in the form of a tube packed with chemicals.
These earths are more for the use of lightning conduction rather than electrical safety earth.
Very popular in India.
Would 230 volt 50 htz 3 phase motor work on 220 volt 60 htz 3 phase?
It would work but it would probably run 20 per cent faster, so if that is not a problem it's OK. But if the load is a fan, the motor might not be able to supply the extra mechanical power at the extra speed, so it would run but it would overheat.
What is the difference between a radial circuit and a ring final circuit?
A 'ring final circuit', or 'ring-main system', is one in which the line conductor starts and ends at the same line terminal, and the neutral conductor starts and ends at the same neutral terminal in the consumer unit. This means that line current can flow it two opposite directions to the same load, meaning that the current-carrying capacity of the conductors is effectively larger than it would be if the same cross-sectional area conductors were used in a radial system. Loads connected to the ring main are then individually fused using fused plugs.
A 'radial circuit' is one in which only one end of the circuit is connected to the line and neutral terminals, with opposite end terminating at a load.
Ring final circuits are more-or-less unique to the United Kingdom, and were introduced around 1947 when a large house-building programme was established to compensate for the amount of properties destroyed in the second world war. At the same time, there was a shortage of copper, and a ring main system was a method of saving copper without reducing load capacity.
How do you calculate Kwh saving after installing capacitor bank?
Adding a capacitor bank makes absolutely no difference whatsoever to the amount of energy consumed (in kilowatt hours). The capacitor bank might reduce the load current, but this does not affect the amount of energy consumed. Anyone who tries to sell you a 'capacitor bank' in order to save you energy is selling a SCAM!
Methods of calculating Ripple voltage in supply without using oscilloscope?
Measure AC voltage with multimeter. It is easiest way to check how big ripple is.
There is no way to 'calculate' value.
Will a motor that has 220 volts and 7 amps have enough power to equal 1 hp?
Yes! One HP equals 749 watts. W = V . I 220 . 7 = 2.056 In reality, with 7 amps in 220 v you have more than 2 HP. By Nonô - BRAZIL Yes! One HP equals 749 watts. If you have 7 amps on 220 v, as watt = volts . amps, 220 . 7 = 1540 watts 1540 / 7498 = 2.056 HP. You have more than 2 hp. By Nonô - BRAZIL
What are the errors that can happen in a medical ventilator?
There are many different errors that can happen in a medical ventilator. The medical ventilator could just freeze up and stop working for example.
Where in the world are maglev trains found?
There is a low speed maglev train in Nagoya Japan called the Linimo, as well as a high-speed maglev train called the Shanghai Transrapid which links Shanghai International Airport and a transit station in Shanghai, China. There are also experimental maglev test lines in Daejeon, South Korea; Yamanashi, Japan; and Power Springs, Georgia, United States. A test facility in Emsland, Germany also just recently closed.
If the core (moving part) of an AC solenoid does not move into position when energized, the current flow stays high (inrush) and overheats the coil. Normally the magnetic properties change and the current drops to a lower holding value so the coil does not overheat. DC solenoids do not have this problem.
SCADA stands for Supervisory Control And Data Acquisition. It generally refers to an industrial control system: a computer system monitoring and controlling a process,A Human-Machine Interface or HMI is the apparatus which presents process data to a human operator, and through this, the human operator, monitors and controls the process.
Why is plastic a bad conductor of electricity?
Generally, the valence electrons in the atoms of the molecules in plastic hang out in Fermi energy levels lower than the energy bands that an electron would have to occupy to support conduction. The electrons are bound to parent atoms, and they also may have some mobility within the molecular matrix of the material, but any energy applied (like voltage) doesn't really get the attention of these electrons. They chill in energy levels too low to be jerked up into the conduction band with any fair amount of applied voltage. And if the electrons are not in or cannot easily reach the conduction band (an energy level high enough to support current flow), the material won't support conduction and is said to be a bad conductor.
The dc input resistance of MOSFET is?
it depends on the type of the circuit you are analyzing..it could be a voltage divider, emitter follower, be specific on what type of circuit and maybe i can help you aobut this question.
What is the concept of complex frequency in basic circuits?
Complex frequency is utilized in electric circuits in order to simplify the math, essentially. It is very similar to the use of phasors, except complex frequency can cover all types of inputs, not just sinusoids.
A series circuit is where there is only one path for the current. As a result, and as a direct consequence of Kirchoff's current law, the current at every point in a series circuit is the same. The two bulbs have the same current flowing through them.
The fourier series of a sine wave is 100% fundamental, 0% any harmonics.
What size cable is needed to supply 415v 250 amp three phase fuseboard?
A 250 MCM copper conductor with a insulation factor of 75 or 90 degrees C is rated at 255 and 265 amps respectively. This conductor can only be load to 80% capacity which allows a working current of 204 and 212 amps respectively. To obtain the full capacity of 250 amps a 350 MCM conductor will be needed. The amp rating for a 350 MCM conductor with an insulation factor of 90 degrees C is 325 amps. 325 x .8 = 260 amps.
Comparison of stepper motor and induction motor?
A stepper motor (or step motor) is a brushless, synchronous
electric motor that can divide a full rotation into a large
number of steps. The motor's position can be controlled
precisely, without any feedback mechanism (see Open-loop
controller). Stepper motors are similar to switched
reluctance motors (which are very large stepping motors
with a reduced pole count, and generally are closed-loop
commutated.)
An induction motor (IM) is a type of
alternating current motor where power is supplied to the
rotating device by means of electromagnetic induction.
