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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
What are at least 2 types of electrical transformers in science?
A variety of electrical transformers are produced for a variety of purposes. All of the types use the same principle discovered by Michael Faraday, and employ many of the same parts. The various types include.
Audio transformers,
Instrument transformers,
Pulse transformers,
Power transformers,
RF transformers.
.
How can hysteresis loss in magnetic material may be reduced?
Hysteresis losses depend on the type of metal used to manufacture the magnetic circuit of a machine. Most magnetic circuits are made from silicon steel. Generally speaking, there's not much you can do to reduce hysteresis losses as that has already been factored in by the machine's designer.
What is the minimum distance to live near high voltage cables?
Technically, the intensity of the electromagnetic fields radiated from electrical transmission lines becomes smaller as the distance from the cable increases, but it never reaches zero. Despite many studies made on the effects of magnetic fields, there is no definitive guide as to what harmful effects high voltage fields have on humans or other living things. The level of risk in being exposed to these fields cannot be categorically stated.
Single or Three phase Ac Circuit?
Both are possible. Single phase requires a neutral (or two phases, such as "Single-phase 240 V) to return the un-used voltage on the "down side" of the generating cycle. Three phases equal "each other out" on the up and down side. One phase generating positively while the other two are at various points of positive and negative on the sine wave to balance each other out.
When you should use synchronous motor instead of capacitor for power factor correction?
Synchronous motors show some interesting properties, which finds applications in power factor correction. The synchronous motor can be run at lagging, unity or leading power factor. The control is with the field excitation, as described below:
- When the field excitation voltage is decreased, the motor runs in lagging power factor. The power factor by which the motor lags varies directly with the drop in excitation voltage. This condition is called under-excitation.
- When the field excitation voltage is made equal to the rated voltage, the motor runs at unity power factor.
- When the field excitation voltage is increased above the rated voltage, the motor runs at leading power factor. And the power factor by which the motor leads varies directly with the increase in field excitation voltage. This condition is called over-excitation.
- The most basic property of sycho motor is that it can be use as a CAPACITOR OR INDUCTOR both. Hence in turn it improves the power factor of system.
The leading power factor operation of synchronous motor finds application in power factor correction. Normally, all the loads connected to the power supply grid run in lagging power factor, which increases reactive power consumption in the grid, thus contributing to additional losses. In such cases, a synchronous motor with no load is connected to the grid and is run over-excited, so that the leading power factor created by synchronous motor compensates the existing lagging power factor in the grid and the overall power factor is brought close to 1 (unity power factor). If unity power factor is maintained in a grid, reactive power losses diminish to zero, increasing the efficiency of the grid. This operation of synchronous motor in over-excited mode to correct the power factor is sometimes called as Synchronous_condenser.
What is voltage regulation of synchronous generator?
The volatge regaulation be calculated by calculating the percentage difference between volatge at no load and voltage at full load
From whom does the word watt came from?
The word "watt" is named after James Watt, a Scottish engineer who played a key role in the development of the steam engine. It is used to measure power, with one watt being equal to one joule of energy per second.
What happens when you add a resistor to a series circuit with a light bulb?
As you add more bulbs to a series circuit that means that the bulbs are in series to one another, therefore the total resistance is the sum of the individual resistance of the bulbs. If you add bulbs of the same resistance,then the rate at which the resistance changes will increase in a constant manner provided the current source is not altered. For instance if the bulb you are using is rated 20v,60w, then the current passing via the bulbs in series is the square of the voltage divided by the power in this case the current is approximately 7amperes.
Where can one purchase an electrical tester?
One can purchase an electrical tester at Amazon. Amazon has a wide variety of these, so there are many options to choose from. Like Amazon, Fluke also sells a wide variety of electrical testers.
Is core loss same as no load loss in transformer?
Yes, that is almost true, apart from a very small copper loss in the primary winding that carries the small magnetising current.
The core loss (iron loss) depends on the applied voltage. This loss is measured by the open-circuit test, carried out at the working voltage.
What are the physical resources of the Philippines?
The Philippines is rich in natural resources, such as minerals, agriculture and marine resources. It is made up of many types of bodies of water and beautiful coast lines.
How do you calculate hp from amps?
1 HP is 746 watts in principle. The power is in watts, and the power is the volts times the amps. For an AC motor the power is the volts times the amps times the power factor times a factor that depends on the power-conversion efficiency of the motor.
How does the earth wire protect you from a short circuit?
An earth wire only " works " under fault conditions in an electrical circuit . The earth or circuit protective conductor protects any conductive part of the system which under normal conditions should not be live , for example the metal casing of a washing machine . The earth , during a short circuit , will complete the circuit and the system will fuse/trip/disconnect if protected suitably .
Why is it important for the switch of the circuit to be open at the start of an activity?
If you mean by activity, working on an electrical circuit, then it is for safety reasons that a switch is opened. Most companies now use a proper lock out procedure so that everyone is aware that the circuit has been locked out. If more than one person is working on the circuit each person is required to have their own personal lock on the open switch.
What products have resistors in them?
resistors are commonly found in electronic devices. a resistor is any material, through inductive reactance or capacitive reactance,which opposes a current. typically by creating a magnetic field or an inverse voltage.
How many lumens does a a 1 watt led bulb produce?
Generally speaking, the lumen per one watt of different LED is different. As far as i known, some LED products can reach 120 lumen per watt or more higher which from lab or some big famous comapny, we called this is lab level, but in fact, most of companies and LED manufactures can not reach this level, theirs LED products are differenet, some of they can reach 80~90 lumen per watt, but some is very low, like companies power, technical level, product develop and many others factor will effect the lumen level. Of course, all of this conclusion is base on the test report of LED product, like lumen, color temperature, CRI, illuminances etc parameters.
Can you use DC current in induction heating?
Induced voltage happens through induction. When a wire goes through a magnetic field a voltage is induced across its ends.
The basic equation is Ampere's law: Curl E = dB/dt at every point, where E is the electric field and B the magnetic flux density.
For a loop of wire Stokes's theorem can be applied to this: Integral E.dl = d/dt of the surface integral of B.dS which says that the induced voltage along the loop equals the rate of change of the magnetic flux linking the area of the loop.
How do you calculate current required?
By Ohm's Law.... Voltage equals Current times Resistance (V=I*R)
So if given the voltage and resistance of a system and applying algebra I=V/R .
How do you find the current rating of a circuit breaker?
A circuit breaker, like a switch, turns power on and off by moving one conductor to touch or not touch another conductor. The gap when not touching has to be large enough that electrons cannot pass through the air to the other conductor, producing a spark. The larger the voltage, the farther it can pass through the air, and the larger the gap must be.
So the rated voltage of a circuit breaker or a fuse is the largest voltage it can safely control.
Answer Take all phases into account. Voltage is measured between two phases of the three phases at one time, so what this means is this...first you read voltage between line 1 and line 2...then you read voltage between line 2 and line 3...and then from line 1 to line 3. Each phase of a 3 phase system is 120 degrees from the other in a 360 degree pattern. It takes all 3 phases to start a 3 phase motor but can run on two. If a 3 phase motor tries to start on two phases it is refered to as single phasing and can damage the motor.
Another Answer
First of all, let's get the terminology correct. The wires that join a three-phase load to its supply are called 'LINE conductors', not 'phase conductors'! This is very important. Phases, which are normally inaccessible, are either the generator windings, the transformer windings, or the individual loads, connected to the line conductors -this can make measuring phase voltages very difficult unless you can access the interior of these machines/loads.
The voltage of a three-phase system is normally defined in terms of its line voltage, not its phase voltage, so one normally measures its line voltage by connecting a voltmeter between any two line conductors or terminals. As the line voltages are determined by the supply system, all line voltages should be the same, regardless of which line conductors you choose to place the voltmeter between.
The important thing, however, and this is something your voltmeter will NOT tell you, is that the three line voltages are out of phase with each other -each lagging its predecessor by 120 electrical degrees. And this is important, because it is the phase displacement between these voltages, not the magnitude of each voltage, that allows -for example- a three-phase motor to self-start.
What is the role of a substation in a power system?
Power lines are conductors that are designed to carry large amounts of electricity. Inside substations, rigid bus is typically used instead of slack conductor, although jumpers to various pieces of equipment are used.
Advantages of at89c51 microcontroller over 8051 microcontroller?
the 8051 microcontrroller is the name doesnt matter easy or not....but the maiin and imp diff between both is at89s51 represents the 8051 chip no....along with the name of company i.e atmel, so all n all both are same thing ......
89c51 have RISC architecture and contains less no of opcodes which are easy for programming. so iti is preferred than 8051.
Will the impedance in a series RL circuit increase as the frequency decreases?
When the frequency of Parallel RL Circuit Increases,XL increases which causes IL (current through inductor) decreases. Decrease in IL causes It (It=Il+Ir) to decrease,which means by relation IT=Vs/Zt ,the Zt (Total Impedance) Increases.
Who discovered electromagnetic induction?
We generally credit Nikola Tesla, the Serbian-American inventor, with the pioneering work of identifying the rotating magnetic induction field idea and applying it to a device that generated torque - rotational energy or force. His work on this occurred in about 1882.
