Electrical Engineering

A: Mica is an insulator used extensively in capacitors and hi quality transformers. It has very good temperature coefficient

A; BUFFER is used for isolation, translation of levels and amplification if needed

Often we want to easily change a resistor value, so we use a variable resistor.

For example, we may want to change the resistor that controls the power sent to a LED, so we can easily make it brighter or dimmer.

Often if we use a variable resistor, there is only a very narrow range that is useful.

Continuing our example, sometimes we use several LEDs, and we use the variable resistor to set them all to the same brightness.

In this case, the resistance range that sets the LED to be twice as bright as the the other LEDs, and the resistance range that sends so much power to the LED that it is permanently destroyed is even less useful.

So we add a fixed resistor in series with the variable resistor -- the fixed resistor sets the minimum net resistance, no matter how we turn the knob on the variable resistor.

In our example, the addition of the fixed resistor allows us to turn the variable resistor throughout its whole range, and the LED gets brighter and dimmer; without that resistor, a certain range of the knob on the variable resistor would allow so much power to go to the LED that it would be destroyed.

It is much more efficient to transmit AC over long distances.

Because using transformers you can convert to very high voltages, and then power transmission then involves much lower currents, so that losses in the transmission line I2R are much reduced. You cannot easily and efficiently convert DC to high voltages.

200 yards to 200 feet is easy, just divide by three.

0.09 square inches means the new wire has about 1.9 times the cross-sectional area of the old one (assuming CM means circular mils). So that would reduce the resistance by a further factor of 1.9.

All told, I'm getting somewhere in the vicinity of 166 "m ohms" (milliohms?).

I did not understand .I'm talking Arabic

Hooking a 24V motor to a 110V source is a certain way of destroying the motor. It'll pull as many amps through its poor circuitry as the source can deliver until either the source's fuse or the motor blows.

Transmission lines are three-phase systems. There are three line conductors in a three-phase system. However, to reduce electric stress at higher voltages, these lines are frequently made up of 'bundled' conductors -so each line might have two, three, or four separate conductors. In addition, transmission towers usually carry separate circuits -i.e. separate three-phase circuits on opposite sides of each tower.

So, in the UK for example, a typical 400-kV transmission line will consist of two, separate, three-phase circuits suspended on each side of each tower, with each line consisting of four bundled conductors. That's 24 conductors.

The shaft still rotates but the generator takes only enough mechanical power from the turbine to overcome friction. Thus very little steam supply is required for the turbine and fuel is used at a very slow rate.

In this condition the generator still runs at synchronous speed but it is a neutral load on the grid, drawing no power and supplying no power.

If the steam were turned off, the generator would continue to run at the same synchronous speed, but as a motor, drawing enough power from the grid connection to overcome friction. In this state the mechanical phase of the rotor would lag slightly (as a load its power factor could be controlled via the field current).

Now if the steam supply were turned up, the phase of the rotor would advance, while the generator would continue running synchronously, but it would now start pumping power into the grid and fuel would be used at a rate proportional to the power supplied.

Thus a turbo-generator set quickly adjusts its rate of fuel consumption according to the power it supplies to the grid. In this way the quantity of fuel used and CO2 emitted (if carbon fuel is used) are closely tied to the amount of energy produced.

'Tappings' are externally-accessible electrical connections to the turns of a transformer's (usually high-voltage) winding. This enables the number of turns to be changed, resulting in a change to the transformer's turns ratio and, therefore, to its voltage ratio.

Tap changing enables the electricity network company to adjust the turns ratio in response to any excessive voltage reduction resulting from a heavy load.

b class means the product did not pass the manufactures top quality check. It could be cosmetic or a slight defect. Usally does not affect product operation and you may not even notice any problem with the device. It will not be warrantied through the manufacture because it was sold at a lower price because of the rating. b class does not mean refurbushed. you are taking a "slight" risk of the product failing, but usally the seller will warranty the product for 1 yr. Most times if the product doesn't fail withing a few weeks, it is usally ok.

The electric generator was first made in 1790 by a man named Aloisio Galvani. Over the years, scientists improved the practical and theoretical parts of the equipment. In 1831, another man (named Michael Faraday), discovered the operating principal of electromagnetic generators. The principle is now called Faraday's Law.

The first workable units though for generating power were created by Nikola Tesla. He is created with the creation of alternating current, which requires a method of creation. He is also credited with the creation of the motor which is very similar in construction to the generator.

I don't see the use of, without a purpose, deliberately seeking a lower power output than possible -- why would you waste energy?

If the purpose is to control power, then the maximum power transfer theorem will predict what can possibly be delivered by the system. The theorem is telling you the design is less than ideal if you measure something less, which is always true. You can ask yourself "Can I possibly improve the design?"

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AC and DC can be differentiated but not in points.

Voltage on primary/Primary turns = Voltage on secondary/Secondary turns

A: The leakage is an additional load to the bridge effect is that the capacitor will get hot then hotter because of it leaks more eventually blows hopefully open or dead short. both of these scenario may save the power supply.

Too vague of a question. As long as it is a closed circuit it will flow.

Yes and no. In order for it to work electrically then your replacement part has to have the same or higher voltage rating, The same value rating is also important (micro farads). And it has to be the same type either AC or DC. A lot of DC capacitors are polarity sensitive and will only successfully work when hooked up in the same polarity. Also keeping the same type of chemistry is important. If the Original type is Electrolytic, Tantalum, Mylar, Silver Mica and so on then pick a replacement part that is the same chemistry as the original. In some applications if you're replacing an existing part with a new one you may have to choose a part that will physically fit and attach in the same way the original part did.

Hydroelectric power is already one of the current methods and has been for well over 100 years.

No it cannot completely replace other means of generating electricity. For one thing most western nations have already maxed out their usage of hydroelectric power and some have actually had to tear down some older dams due to environmental damage caused by the dam.

Rivers that can be economically dammed to generate power are a very limited resource.

They don't need to, but if it is digital, it may have them. (Ohmmeters must have a battery)

Get enough photons into "population inversion" as you can between two mirrors an it will lase. One mirror must allow some light out to work. Population inversion caused by pumping the cavity with light or electrons.