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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 increase in current result in increase in electrical consumption?
As you are billed on the consumption of wattage and wattage is the product of amp times volts the answer to your question is yes. An increase in current will result in an increase in electrical consumption.
Additional AnswerResidential consumers are billed on their energyconsumption (there is no such thing as 'electrical consumption' as 'electricity' is not a measurable quantity!), expressed in kilowatt hours.
There may be several reasons for an increase in load current. For example, if the residential load has a low power factor, it will be drawing more current than necessary, but the energy consumed will be no different from if the load had a high power factor.
So, for residential loads, an increase in load current doesn't necessarily mean a higher energy consumption.
How do you know when a Transistor has burnt out?
The first clue is a burnt board. There are many different types of transistors which complicates determining "for sure", beyond this visual observation. The absolute best way is to remove it from the circuit and test it per the specifications in the data sheet for that particular transistor.
A simple test to see if "maybe" it is good can be done by checking the base or gate voltage to emitter. This is usually .5-.7 volts in a BJT. If it is burnt out, or there is not enough voltage applied to the base, it may be burnt out. If you can open the circuit up to verify a small current is flowing from base to emitter in a BJT (in a MOSFET, there shouldn't be current flow), and verify current flow from collector to emiitter. If one of these is now an open (I.E. no current flow) you can probably assume this is a burnt out transistor.
So...the simple, sad truth is it is a lot of hassle to check this! In my opinion it is just easier to replace the transistor, assuming you can determine its' exact model number (some manufacturers scrub these, making it harder to reverse engineer things).
Why electrons does not collide during AC?
Who says they don't?
I can't resist the urge to quote "The Hitchhikers Guide" saying space is REALLY big... electrons are tiny compared to the "empty" space in atoms and molecules. There's a low probability that two will intersect.
How many watts can go through 22AWG wire and do the amps and volts matter?
Wire size is rated in Ampacity, so yes, You have to divide watts by the voltage to give you the current (Amps). Strange question, the only use for 22AWG wire that I know of is analogue control, 24 volts, 4-20mA. 22AWG is not even listed in the NEC as a Current Carrying Conductor.
What is ripple frequency of 50 Hz 3 phase full ac supply?
A single phase half wave rectifier outputs ripple the same frequency as the input.
A single phase full wave rectifier outputs ripple fundamental twice the input frequency (assuming balanced recitfiers).
A three phase full wave rectifier outputs ripple fundamental six times the input frequency. So 50 Hz input would yield 300 Hz ripple.
See Sources and Related Links for more information.
1500 kva transformer equals how many amps at 480 volts?
480 volts is probably 3-phase (Line to line) voltage, so:
1500K / (480 x 1.732) = I = 1804Amps
For what are high voltage power supplies typically used for?
High voltage power supplies have many uses. It is most commonly used to supply power from a device to the circuit. These are great for people who need to supply their house with power.
How do vfd's change the AC to dc current and back into AC?
Variable frequency drives use a rectifier to "chop off" the top part of the ac wave, then use capacitors to "fill in" the gaps in the voltage, making a "near dc" power. They use IGBTs, a fancy term for a high speed, high current transistor, or electronic switch, to pulse the "near dc" power out to the motor, in a pattern that appears like ac to the motor.
How diodes protect the circuit from back emf which is generated by relay coils?
The relay coil is an inductor and, as such, resists a change in current. When you de-energize the coil, it attempts to maintain the current flow, but it cannot because you have opened the circuit. This causes a high voltage spike to be developed across the coil which is of opposite polarity to the normal current. The diode conducts, dissipating the current and preventing the voltage from exceeding the safe operating voltage of the driving circuit, often a transistor.
The Diode is wired so that it is in reverse during normal operation, so no current passes through the diode and does not affect the coil it is parallel connected to.
Why is parallel resonant circuit called a rejector circuit?
because at resonance frequency in LRC parallel circuit,impedance is high, so it minimize the current. thus we say its a rejector circuit .
Why were the electricity regulations brought in to use?
If electrical wiring and devices are used in an unsafe manner, it is very possible that electrocution or fires can result from failure to follow safe practice.
Therefore, it is very important that electrical design, installation, and use be done properly, by workers who are properly trained and experienced.
What is difference between encoder and multiplexer in digital electronics?
An encoder refers to a device that is used to change a signal or data into a code. Whereas a Multiplexer or mux is a device which performs multiplexing or it takes information from more than one channels and outputs into a single channel. Thus a multiplexer is basically a kind of encoder where its function is to combine multiple inputs into one output.
Only if you plug yourself in, The answer is no, nerves transmit tiny DC electrical charges.
What is the difference between ohms and mohms?
ohms is the SI unit of resistance MHO (siemens) is the SI unit of reciprocal of resistance ie conductance
Why are satellite orbits depicted as sine-wave shapes?
The sine wave represents 360 degrees or a full circle. As the satellite revolves 360 degrees around the earth in its orbit this is how it is represented on a flat surface.
What is Paradoxical excitation?
From what I've gathered Paradoxical excitation is a function of the brain, a disorder that can be caused by certain medication, a sort of "wired" or excitable feeling. There are medical research cases regarding this. Google it and you can read the case studies.
What is a artificial dielectric?
The dielectric is composed of "molecules" that are actually perfectly conducting spheres. These have radius R and are in a cubic array with spacing much greater than the radius R. With the application of a voltage, the spheres acquire the positive and negative surface charges on their northern and southern poles required to make their surfaces equipotentials. In so far as the field outside the spheres is concerned, the system is modeled as an array of dipoles, each induced by the applied field.
How can a relay circuit be used?
For the use in electrical engineereing:
Generally speaking, using a relay may involve anything from a very robust approach to an extremely delicate approach. Consider some aspects of a relay. A relay has contacts, arcing and sparking because of back e.m.f from load circuits may damage these contacts and reduce the life span of the device. Some inductive applications might require a low value capacitor across the relay contacts. Just remember that the peak voltage (not rms or AC) of the mains running through the contacts is not more than the rated capacitor voltage value. Do not use polarized capacitors where AC is used. Often a 10nF might make a difference already depending on your back e.m.f of the load obviously. It will also reduce some EMI (electromagnetic interference)
Even if your DC control signal may only see resistance of the coil at the time the coil is on or off. A coil that has inductance and store magnetic energy, the same as any coil will also produce back e.m.f when potential is removed. The collapse of the magnetic field cause a high potential difference, possibly thousands of volts at high frequency. The frequency may in fact be so high that regular diodes or transistors might not stop it. One would recommend a series resistor and use the collector of a NPN transistor with it's emitter to the ground to switch the relay on or off via the base, be sure to have a base resistor to protect the source of the control signal as well as the B-E junction of the transistor, calculation as follow:
Rs = collector series resistor
Rb = is base series resister
beta = current gain for the transistor
Vsource = the control signal voltage minimum that will turn relay on or off
By applying ohm's law we get:
Rc = [Rrelay x (VCC-Vrelay -Vce)]/(Vrelay )
Rb = (Vsource-Vbe)/[(Vrelay/(Relay x Beta)) x 10]
{use factor 10 to compensate for error in beta values}
Don't ever be to comfortable with the fact that there are no electrical connection between the contacts and the coil of a relay. Do not think relays are safe to use with computers or related micro controller devices because they are electrically isolated. It will be a bad mistake!! There are back e.m.f. from the coil aswell as e.m.i from contacts what is induced back into the coil when it has high impedance across it.
It's then recommended to have a fast recovery diode in reverse bias condition across the coil to prevent back e.m.f. of finding its way back home.
This is recommended to protect the driving signal source. Often in small relays using HC or TTL family logic to drive it via a transistor to a transorb or fast recovery diode across the coil may be good enough. Especially if you use it for your self and not to design a heart-lung machine for a hospital.
But if you have micro controllers, computer ports. The damage of a strong back e.m.f may be more than what you bargain for and will probably happen at the worst time in the wrong place. The best is to use a opto-coupler.
The control source will via a series resistor, let say about (330R for a 5V signal) switch an internal LED inside the opto-coupler device on. The light will drive a photo-transistor into forward bias condition. That can be used to drive the transistor that will energize the relay. Since there is no electrical connection between the output pin of the microcontroller that produce the control signal and the relay coil. There is only a one way communication via a light beam. This is by far safer. It creates a typical, 2500V isolation between the robust electrical circuit and it's e.m.f 's, and the sensitive and delicate micro controller or computer circuit environment. A dip in Vcc or pin for less than a millionth of a second dipping with 2 volt or spiking can cause freezing, erratic response or failure of the micro controller. For good electronic design opto-couplers are a very important part of a reliable control system that use micro controllers to control relay output with.
From your question it's hard to tell what might be the source of your problem. Is this a primary source to a machine or multiple circuits or from a transformer to just one device like a motor. If it is a short to ground then it should be tripping fuses or breakers if not then you have a unsafe situation in a ungrounded system. If the power is from a transformer then it may have an open winding or blown fuse on either the primary or secondary side.
What is differences between MPP and APP Capacitors and how it recognize?
This is for capacitors
MPP means metalised poly propolin film & APP means a
All Poly Propolin film
heat developed = 5*5*20*30 = 15000 joules
AnswerWith the information supplied, you can only determine the work done (W) by the circuit, not the heat (Q). To do so, you will need to know the mass (m) and specific heat capacity (C) of the conductor, and the temperature-difference between the conductor and its surroundings. The equation you need to do this is:
W - Q = m C (Tf-Ti)
With the information supplied, you can only calculate the work done: W = I2Rt.
How the DC offsets are generated in the system?
For fault conditions, the DC offset is caused by where the fault occurs on the voltage waveform.
When the fault initially occurs, the voltage can be looked at as an AC waveform superimposed onto an impulse response (A DC wave). The magnitude of the impulse is equivalent to the voltage when the fault initiated (flash over usually occurs near a voltage peak, providing a potentially large DC component).
The inductance of the system (j*w*L) appears as 0 impedance to this DC voltage.
Z (impedance) = R (resistance) + X (inductance), usually X >> R, X = j*w*L
Since X = 0 for the impulse, there is an initial large current since V = I / Z, and Z = R initially.
This current slowly dies off based on the time constant of the circuit, 1/(L*R).
A lot of times you will hear talk of the the DC component being caused by the "X/R ratio". The higher this ratio, the larger the DC component (generally) and the longer the time constant generally is (although this is not always the case).
Similar analysis applies to other causes of DC offset.
i think its also like the form of torque by its shake with that of osillating
No. An LED (light emitting diode) allows current to flow in one direction, thus it cannot alternate as is implied by "an AC source".
ANSWER: YES they can. Any diode can work with AC They can work from AC line directly. My overhead light in my kitchen are across 120 AC now for 8 years. But then again I know what I am doing
