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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
Picture of a circuit with two dry cell in a series?
Below are two DC sources in series.
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You can write this as a complex number; the resistance is the real part, the reactance is the imaginary part (negative, for a capacitive reactance): 15 + j10 kilohms. ("j" is used instead of "i", to avoid confusion with current, which is symbolized by "i".) This is in rectangular coordinates; with a scientific calculator you can use rectangular --> polar conversion, to get the absolute value and the angle. To get just the absolute value, use Pythagoras' Theorem, which in this case gives about 18 kilohms.
You can write this as a complex number; the resistance is the real part, the reactance is the imaginary part (negative, for a capacitive reactance): 15 + j10 kilohms. ("j" is used instead of "i", to avoid confusion with current, which is symbolized by "i".) This is in rectangular coordinates; with a scientific calculator you can use rectangular --> polar conversion, to get the absolute value and the angle. To get just the absolute value, use Pythagoras' Theorem, which in this case gives about 18 kilohms.
You can write this as a complex number; the resistance is the real part, the reactance is the imaginary part (negative, for a capacitive reactance): 15 + j10 kilohms. ("j" is used instead of "i", to avoid confusion with current, which is symbolized by "i".) This is in rectangular coordinates; with a scientific calculator you can use rectangular --> polar conversion, to get the absolute value and the angle. To get just the absolute value, use Pythagoras' Theorem, which in this case gives about 18 kilohms.
You can write this as a complex number; the resistance is the real part, the reactance is the imaginary part (negative, for a capacitive reactance): 15 + j10 kilohms. ("j" is used instead of "i", to avoid confusion with current, which is symbolized by "i".) This is in rectangular coordinates; with a scientific calculator you can use rectangular --> polar conversion, to get the absolute value and the angle. To get just the absolute value, use Pythagoras' Theorem, which in this case gives about 18 kilohms.
What is the voltage across a device that draws 2A and dissipates 12w?
The voltage across a DC device that draws 2A and consumes 12Wh/h is 12/2 or six volts.
What address does an 8085 start at and what address do the interrupts go to?
At reset, the 8085 starts at location 0000H. The INTR interrupt goes wherever the interrupt opcode says to go. The TRAP interrupt goes to 0024H. The RST5.5, RST6.5, and RST7.5 interrupts go to 002CH, 0034H, and 003CH respectively. The RST X interrupts goto 0000H plus 10H times X, i.e. 0000H, 0008H, 0010H, ..., 0038H.
802.3af
How can tap changer be used to coordinate voltage control?
Tap changing is the ability available in many power transformers to control the voltage.
How it works:: As we know the energy conservation for transformers V1*I1=V2*I2 [1 is primary side and 2 is secondary]..So suppose your system requirement is 220VAC transformer output and incoming voltage is 415VAC [Tapped input with appx +-10% ,400-415-440],then in case of low output voltage or higher output voltage [lesser than or greater than 220Vac] can be rectified by changing the input side taps only [By increasing and decreasing the input tap setting as said above].
Essentially what is being done is a few turns are being added or removed from one winding, which results in a different ratio N1/N2, resulting in different secondary voltage vs. primary voltage.
This can be used to coordinate voltage control by having the LTC operate prior to automatic cap banks on the bulk electric system, and prior to power plants modifying their output. transformers should be tapped slower than the local lower voltage cap banks. Basically, the lowest voltage voltage regulation equipment should begin tapping (as a general rule) or turning on. If these cannot fix the problem, the higher voltage equipment will kick in.
Which type of material that allows electricity to flow but not as freely?
Note that "electricity" doesn't flow, only current does, which is one aspect of electricity, does. Current is the flow of electrons.
Good conductors are metals, such as copper or aluminum.
Materials that allow the flow of electrons, but not as freely as good conductors are known as semiconductors. These are primarily silicon or germanium, that is "doped" with specific types of impurities to allow their current to be better controlled by the application of a voltage. Heat will also increase the flow of electrons in a semiconductor.
12volt landscape lighting is this ac or dc?
This is DC, you need to talk to someone who knows what they are doing,unless
you get a kit that has everything already to go. Because everything must be matched
from the lights, wire, distance, how many, transformer. Lowes has a few ok kits.
If you where looking at say seagull or hinkley, lighting, which are not kits and are expensive, the system must be designed, and your looking at 300.00-600.00
just for a transformer.
I install custom outdoor landscape lighting.
DC is a very safe way to go,, over hard wired lighting for landscaping.
Draw and identify the parts of an electric circuit?
The pile or battery is represented by a staggered series of long and short vertical lines:
|i|i|i (no dots) with the short line being the anode and the long one the cathode. A sharp squiggly line represents the resistance, such as an LED. Most circuits also have a switch, a method of opening and closing (turning the circuit on or off). There are symbols for diodes, capacitors, etc.
What is synchronisation and asynchronisation?
Synchronisation means to start an sequence of events at same time,
Asynchronisation is opposite of this.
4-20ma is a type of signal transmission.
- A process value, such as pressure, RPM, or whatever, is converted into a current in the range of 4ma to 20ma and sent out on a twisted pair cable.
- The receiver passes the current through a resistor, converting it back to voltage, and processes it accordingly. If that resistor were 250 ohms, the voltage would be 1-5v.
- An offset of 4ma is used so that the receiver can detect an open connection.
- The ground or power reference is usually maintained at the transmitter, but sometimes it is at the receiver.
- A twisted pair cable is used so that the effect of common mode noise is minimized.
- The receiver is usually an opamp so that the effect of common mode voltage is minimized.
You have 240volts and a load of 50 amps what is the kva?
A voltage of 240 volts is not a common three phase voltage. Single phase kva of 240 voltas and 50 amps is I x E/1000 = 240 x 50 = 12000/1000 = 12 kVa
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Assuming the 240 volts is phase to phase voltage, and this is a three phase application:
KVA = V*I*sqrt (3) = 20.78KVA
What materials were used to make the first electric doorbell?
A bell, a coil with an iron core, a striker-spring, a fixed switch-contact and two brass terminals were probably all mounted on a polished or varnished wooden base.
The bell was probably made of brass, the spring of the striker was probably made of tempered steel and its "pole-piece" was probably a small piece of iron mounted about half-way along the striker-spring.
One end of the striker-spring was fixed to the wooden base-board of the bell. The other end of the striker-spring probably carried a small piece of brass mounted so as to strike the bell. That small piece of brass was called the "striker".
The coil was probably made of very thin insulated copper wire wound around an iron core.
The striker-spring also carried a switch contact which could touch the fixed switch-contact (which was mounted on the base-board) only when the striker was at rest i.e. when its pole-piece was not being attracted to the iron core of the coil.
The electric bell's circuit was probably set up to connect the "+" side of the battery to one terminal of the bell-push. The other terminal of the bell-push was connected to one of a pair of brass terminals mounted on the base-board and that terminal was connected to the striker-spring's switch-contact.
The fixed switch-contact on the base-board was connected to one end of the coil. The other end of the coil was connected to the other brass terminal from where it was connected to the "-" side of the battery.
The battery might have been put into a separate battery box if it was made up from some 'C' cells or similar. If they didn't use small cells they may have used an old-style very heavy glass "accumulator" and it would probably have been placed on the floor somewhere out of the way, such as in a larder or a pantry.
When the bell-push was pressed, current flowed:
- from the battery to the striker-spring's contact and then
- via the contact fixed to the base-board to
- the coil, so that
- its iron core would be magnetized and
- it attracted the striker's pole-piece.
- That made the striker (on the "free" end of the striker-spring) strike the bell and also the
- contacts opened to break the circuit, allowing the striker, under the influence of its spring, to
- move away from bell and the coil's core.
- This "going-back" movement of the striker would re-connect the circuit (via the striker-spring's moving switch-contact and the base-board's fixed switch-contact) and
- the coil's core would again attract the striker-spring's pole-piece and thus
- ring the bell again and also break the circuit again.
Those "to-and-fro" movements of the striker-spring would continue to ring the bell for as long as the bell-push was pressed.
Why is a motor is a reverse function of generator?
from Faraday's laws its clear that when ever there is change in flux, an emf is produced. in a dc motor there are permanent magnets that produce a magnetic flux. If the shaft of the motor is rotated, which in tern rotates the coil that is placed in the magnetic field. Thus, changing the flux that cuts the coil. since there is change in flux an emf is induced.thus, a dc motor can be used as a generator.
What is the caused of unbalance of current during parallel running of two generator?
That depends on if the two machines are of equal KVA rating and also what type of Generator Control (Isochronous or Droop) each of the machines uses.
What class of amplifier conducts for 100 percent of a cycle?
Class A. Wikipedia has a really good set of data to give you a start on understanding amplifier classes.
What is the function of a earth wire in transmission line?
The earth conductor is not normally used for communications, but the line conductors frequently are. Often 'communications' has nothing to do with telephone conversations, but more to do with data transmission - usually related to protective systems for the lines themselves. To prevent these communications signals from straying to other parts of the electrical transmission/distribution network, the ends of the conductors used for this purpose are fitted with inductors which offer a high impedance to the high-frequency communications signals, effectively blocking the signals from going further into the network.
Does voltage on ground mean open ground?
Voltage on ground can mean an open ground. It can also mean (high) current on ground, due to a ground fault such as reversed neutral and ground.
Difference between thick and thin film integrated circuits?
they have differe.nt method of deposition of film of conducting material. Hence, the difference between two is their fabrication process.
Is a Potential Transformer a step down transformer?
PT's are typically used for metering and relaying purposes to sample the power system voltage and phase angles. The primary is at line voltage, and the secondary is typically between 66 - 120 volts (depending on primary connection, Line to Line or Line to Neutral). So yes, PT's are step down transformers.
Transjugular Intrahepatic Porto-Systemic shunt?
I will answer this question in sections, as I have done extensive research on this, as my husband is going to be possibly be having this procedure.
The "Trans-Jugular Intrahepatic Portosystemic Shunt", or the "TIPPS PROCEDURE", is done by an Interventional Radiologist. This simply means it is done by a Radiologist that is trained to do various procedures with the assistance of some type of device, and in this case, a Fluoroscope is utilized.
The procedure is done for multiple reasons, but in my husband's case, it will be done because he has End Stage Liver Failure, with Stage 4 Cirrhosis, (which is essentially scarring of the liver tissue), and ascites (fluid that builds up in the abdominal cavity), because the liver cannot filter it out due to all of this scarring and damage.
This results in ESLF Patients having to have "paracentesis" procedures done frequently, to drain such fluid, as it can cause a host of complications if left in the abdominal cavity.
The theory goes that this procedure will , over a period of days or even months, help to keep this ascites fluid from collecting in the abdominal cavity, and increase blood flow to the liver.
There are several complications , however, and though the procedure is decidedly pain free, the patient is watched carefully after the procedure for signs of bleeding, and increased confusion, or "Hepatic Encephalopathy" which occurs in one out of three patients who have this procedure. This condition occurs when toxins from the liver's inability to process fluids build up, (ascites fluid is an example) and goes directly to the brain, causing cognitive and functional impairment, including confusion, drowsiness, and sometimes a coma.
When this occurs, it is reversible, and medications are utilized to reverse the condition.
(The average hospitalization time for a patient who does not have any complications from the procedure is three days)
The TIPPS procedure can also cause the End Stage Liver Failure patent's MELD score to significantly rise, and this is a scoring system put forth by the Federally funded (USA) UNOS Program, for the purpose of evaluating in a fair and concise fashion who needs a liver transplant the soonest, who is the sickest. When the "MELD" (Model for End Stage Liver Disease) Score rises, it does put the patient higher up on the list, but the hazard is that there might not BE a liver available when it is most needed.
It is, unfortunately, (in this humble writer's opinion) as with most transplants, a game of pros and cons.
The PROS of this procedure are (hopefully) the following:
1. reduced pressure drop over the liver
2. decreased PORTAL VENOUS PRESSURE
3. decreases the effective vascular resistance of the liver.
4. lessens the pressure on the blood vessels in the intestine so that future bleeding is less likely to occur. Reduced pressure also makes less fluid develop
IMPORTANT WORDS TO KNOW ABOUT THIS PROCEDURE: REFERENCE: www.wordsreference.com)
SHUNT- shunt. implant consisting of a tube made of plastic or rubber; for draining fluids within the body
SHEATH- an enveloping structure or covering, enclosing an animal or plant organ or part
STENT-a device placed in a body structure, (such as a blood vessel or the gastrointestinal tract) to provide support and keep the structure open
The procedure is done by gaining Intravenous access to the Jugular Vein of the neck
. Once access is confirmed, a guide-wire and an introducer "sheath" are inserted,placed to help the shunt's placement. This helps the radiologist gain access to the Hepatic Vein, by going through the Vena Cava. (simply put, the "Vena Cava" is a vein that is attached to the heart)
The "Shunt" is created by advancing a special needle through the "sheath system" to connect the Hepatic Vein to the large Portal Vein, which is near the center of the liver. The channel for the "shunt" is next created by inflating an angioplasty balloon within the liver, along the tract created by the special needle.
The "shunt" is completed by placing a special mesh tube known as a "stent", or "endograft".to maintain the tract to the Portal Vein which has the higher pressure, and the Hepatic Vein, which has the lower pressure.
After the procedure, the Interventional Radiologist takes fluoroscope pictures to show proper placement.
*This is not a complete answer to what this procedure involves, and it needs extensive editing. I look forward to this editing by professionals , of which I am not.
This is only the result of several days of research I have conducted, along with the words of our Transplant Physician.
