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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 can calculate HT cable size for 500mva transformer rating and voltage 11kv?
500Mw at 11kv works out to 45000 a
a bit big for any wire manufactured on this planet
suggest you go to a more practical voltage like 132,000V
AnswerSince we are inevitably talking about a three-phase transformer, the line current is determined from
IL= rated apparent power / (1.732 x UL) = (500 x 106) / 1.732 x 11 x 103)
...which works out at 26 244 A which, as the original answer suggests, is not a practical value for this combination.
Did you mean e. coli? If so then:
A bacillus (Escherichia coli) normally found in the human gastrointestinal tract and existing as numerous strains, some of which are responsible for diarrheal diseases. Other strains have been used experimentally in molecular Biology.
Read more: escherichia-coli
Why a lamp cannot run with the telephone line voltage?
A lamp can be run by power from a telephone line.
How many amps does a five horse power motor draw?
It depends on the voltage-- I think at 110v it's 4 amps per hp
How does an electrical generator work on the basis of the principle of electromagnetic induction?
hope this helps :)
What is the main difference between earth wire and fuse wire?
=== === Fuse wire is just as its name implies: it is some wire made specially to carry only a certain amount of current, which is known as its "designed failure current", when it is being used in a cartridge or a rewirable a fuse carrier that is wired with a certain length of the fuse wire. If the current passing through the fuse exceeds that designed failure current the fuse wire gets so hot that it melts and breaks the circuit. That should help to protect the power supply cables from being overloaded as well as protecting the supplied appliance or appliances from being damaged. In either case the fuse should help to prevent a dangerous fire from starting. A fuse may also help to prevent a person using an appliance from getting a dangerous electric shock but that is not the main purpose of fitting a fuse.
The main purpose of fitting a fuse is for overload and fire protection. Earth wire is, again, just as its name implies: it is wire used to connect the frames and outer casings of appliances and power supply panels to the earth. See the related question and answer for more details about this.
=== === <><><> It is easier to say what is similar, since they are completely different things.
They both conduct electricity, are usually made of metal, and both are important to safety. Other than that, they are nothing alike.
A fuse is a device that breaks the circuit when the current exceeds a predetermined value.
An earth wire, also called the ground wire, as the name implies, connects a circuit or a device to ground.
The R2 Builders Club has "official" plans, and a great community of people from artisans to engineers. Check out astromech.net to learn more about building your very own R2-D2.
Long Term Evolution (LTE) is the project name of a new air interface for wireless access being developed by the Third Generation Partnership Project (3GPP). LTE is the evolution of 3GPP's Universal Mobile Telecommunication System (UMTS) towards an all-IP network. The LTE specifications provide a framework for increasing capacity, improving spectrum efficiency, improving cell-edge performance, and reducing latency. Many of the targets for LTE are similar to those for the continuing development of High Speed Packet Access (HSPA) - generally known as HSPA+ - although LTE has some specific additional capabilities such as flexible channel bandwidths and the advantages of Orthogonal Frequency Division Multiple Access (OFDMA). LTE is being developed in Releases 8 and 9 of the 3GPP specifications.
To meet the demand for ever-higher data rates, LTE offers a 100 Mbps download rate and 50 Mbps upload rate for every 20 MHz of spectrum. Support is intended for even higher rates, to 326.4 Mbps in the downlink, using multiple antenna configurations. To allow the use of both new and existing frequency bands, LTE provides scalable bandwidth from 1.4 MHz to 20 MHz in both the downlink and the uplink. LTE is optimized for low speeds (0 - 15 km/h) but will still provide high performance to 120 km/h with support for mobility maintained up to 350 km/h. 3GPP are considering support for even higher speeds up to 500 km/h.
Downlink Peak Data Rates
(64QAM)
Antenna configuration
SISO
2x2 MIMO
4x4 MIMO
Peak data rate
Mbps
100
172.8
326.4
Uplink Peak Data Rates
(single antenna)
Modulation depth
QPSK
16QAM
64QAM
Peak data rate
Mbps
50
57.6
86.4
Figure 1: Peak data rate targets for LTE1
Capacitor contains a dielectric sandwitched between two plates.
So, it act as a charge storage device.
When dc supply is given,it gets charged to its maximum capacity or potential equal to the supply, and then it act as a open circuit, since it has no way to discharge.
A type of "pressure" that drives electrical charges through a circuit. Voltage is how the electric potential energy differences are measured.
Why 60w bulb more bright than 100w bulb connected in series?
There is insufficient information in the question to answer it. In series with what? Please restate the question.
How do you calculate welding machine demand current?
To calculate the current you need to take theWatt rating of your welder and divide this by the voltage youhave setthe machine at- this gives the amperage.
So for a 1440 watt welder running at 12v the current would be:
1440 watt/ 12v = 120 Amps
The answer would be d 900Hz, because it is 900 is not 200 does not go into 900 evenly. The pipe will resonate a frequencies that 200 will go into evenly.
Why ammeters are connected in series?
Because, in series connection the current is same in all resistors, so the ammeter deflection for finding current is same in each ammeter.
It doesn't matter, unless we're talking about some bulbs with integrated switching power supplies, in which case it might make sense to offset (distance) them by about (SwitchingFrequency / NumberOfBulbs) Hz, to make the general load appear mostly resistive. But in about 99.9% of the cases, the placement of a load (and a light bulb is a load) does not change the amount of current it uses as it's a property of the light bulb itself.
Of course, with LED lights it's possible to "go creative" with the placements of the LEDs and their resistors in such a way as to minimize current draw and power dissipation through heat, but I fear the gains would very well be rather negligible. Also, in-depth knowledge of said resistors and LEDs would be needed if someone were to undertake such an endeavour.
What is difference between spn and tpn mcb db?
TPN MCB means Triple pole Neutral Miniature Circuit Breaker where as SPN MCB means single phase Neutral MCB.
Why at low frequency current and power dissipation is high?
we know that frequency and time period are inversely proportional so as frequency decreases time period increases resulting in larger current flow thus increasing the dissipation.
P=I^2R. 80^2=6400*2=12,800 Watts. That is for D.C. For A.C. you would use the R.M.S. or average wattage.
What are merits and demerits of transformer connected in parallel?
Followings are merits and demerits of parallel operations of transformers:
Merits
1. Increasing load demand on substation can meet by connecting transformers in parallel.
2. Maintenance of individual transformer with low rating (Instead of one Big transformer with high rating)becomes easy and can be done without affecting power supply.
3. In case of any fault, faulty transformer can be removed from the system and others may continue feeding the load.
4. Power reliability of substation is increased.
Demerits
1.Parallel operation needs very much attention and correctness.
2.Phase sequence , Voltage Ratings , % impedance drop and polarities these few things comes in picture which needs to be taken care when doing parallel operation.
Why does brushless motor have at least 3 wires?
A brushless motor is "inside out" compared to your brushed motor. The windings are glued to the inside of the can, and the permanent magnets are bonded to the rotor. Since the wires don't move, you don't need brushes to transfer the electricity.
Take a look at the commutator on the brushed motor. It's cut into multiple sections. Depending on which two sections are in contact with the brushes at any given time, different sections of the windings are energized, creating the magnetic fields that push and/or pull against the fixed magnets in the can.
There are three wires coming from a brushless motor. Inside, all three wires are connected, and wound such that passing DC current through any two connections will create a magnetic field, making the rotor turn a partial revolution. The computerized electronic speed control "commutates" a brushless motor by switching which two wires are being energized in a sequence.
Sensored and sensorless are two types of brushless motors. Sensored motors have a separate sensor, and an additional five wires, that tells the controller which direction and how fast the motor is turning. These are more complicated, more expensive, and difficult to reverse. SensorLESS motors use the fact that when a motor is coasting, it's generating electricity to see which direction and how fast the motor is turning. Knowing this information is crucial to making the motor turn in the correct direction, and knowing which two wires to pass current through at any given time to keep it turning in that direction.
-not my post, taken from another site.
What is a measure of the energy electrons transfer to a circuit as they flow?
The standard unit of electric energy is the Watt Hour.
Where are some places where you can get a education in electrical engineering?
I AM PROUD TO RECOMMEND TO TAKE BACHELOR OF SCIENCE IN ELECTRICAL ENGINEERING IN THE PHILIPPINES FOR FIVE (5) YEARS. THEN TAKE AND PASS THE BOARD EXAMINATION TO BE A CERTIFIED / REGISTERED ELECTRICAL ENGINEER AND BE RECOGNIZED BY THE GOVERMENT TO PRACTICE YOUR PROFESSION WITH PROFESSIONAL ETHICS. OR ELSE YOU WILL REMAIN ENGINEER WITH "ING" - (ENGINEERING).
IR Drop means voltage drop. As voltage drop across any resistance is product of current (I) passing through resistance and resistance value(R ) , it is often written as IR drop.
How can you test a transistor?
Next, for NPN transistors connect the ohmmeter's positive lead to the base. Briefly touch the other meter lead to the transistor's Collector, then to the transistor's Emitter. Both connections should show a low-hm's reading: a diode-type connection. Then, connect the meter's negative lead to the transistor Base, and again touch the other meter lead to each of the other transistor pins. The meter should show open circuit or infinite ohms on both pins, indicating reverse-biased diodes.
If the transistor is PNP, just reverse the meter leads to perform the above tests. Touch the meter's negative lead to the Base pin, then verify that the Emitter and Collector pins behave as "turned on" diodes. Touch the meter's positive lead to the Base, and verify that the Collector and Emitter are acting like turned-off diodes.
Testing for "transistor" function, locating the EmitterIf you use your wet fingers as a resistor, sometimes you can use your ohmmeter to check for amplifier function, and also detect which pin is the emitter.First test for diode function in order to locate the transistor's Base pin. Connect your ohmmeter between the other two pins (no connection to Base, yet.) Wet your fingers and touch the Base at the same time as one of the other pins. Note the ohms reading if any. Then touch your fingers between Base and the other transistor pin. Was one ohms reading much lower than the other? If not, then reverse the ohmmeter leads. Then touch your fingers between Base and one pin, then Base and the other pin. When you find one ohmmeter reading which is much lower than all the others, then you've located the proper polarity for transistor amplification. During the lowest ohms reading, your wet fingers were connected between Base and Collector. The other transistor pin then has to be the Emitter. (You can also perform this whole test more reliably by using a 1K resistor in place of your wet fingers!)
Testing an FETIt's a bit more difficult, but FETs can be tested using an ohmmeter, a 9v battery, and wet fingers. (During low-humidity winter weather, when high static voltages are present, you might want to wear a grounding strap!)First let's test for correct operation of a common N-channel depletion-mode MOSFET. Connect your ohmmeter between the FET's Source and Drain pins, with the positive meter lead on the Drain. While watching the ohms reading, touch the 9V battery's negative terminal to the Source or Drain, then use your wet fingers to briefly connect the battery's positive terminal to the transistor Gate pin. The ohms value between Source and Drain should become low. Remove the battery and briefly touch your wet fingers between Source, Drain, and Gate. The ohms reading should go high again. You've just applied and removed a charge to the floating Gate pin, switching the transistor on, then off again.
For testing a P-channel FET, just reverse all the polarities. Connect the ohmmeter to Source and Drain (positive meter lead to Source.) Use your wet fingers to touch the battery's negative terminal to the Gate pin (with battery positive touching Source or Drain.) That should make the ohms value go low.)
NOTE ON ALL OF THE ABOVE: I assume that the transistor is disconnected from any other circuit. If your transistor is soldered into a circuit board, most of these tests won't work.
