Electronics Engineering

generally voltmeters are connected in parallel in the circuit.If the voltmeter resistance is lower as it increases the current rating,because by connecting parallel we are decreasing the resistance,so if the voltmeter resistance is not too much higher it leads to burning of the meter,For that we can conclude that the in ideal the voltmeter has infinite resistance.

In an electrolytic capacitor the dielectric is a thin corrosion layer formed on the surface of a metal plate, the other plate of the capacitor is a moist electrolyte paste. This very thin dielectric allows electrolytic capacitors to have very high values of capacitance in small packages, but has two disadvantages: low breakdown voltage & polarization of the capacitor.

It is very important that the polarity of an electrolytic capacitor not be reversed. If the polarity is reversed the thin corrosion layer erodes until the capacitor has no dielectric and shorts out, allowing electrolyses to produce hydrogen and oxygen gas in the moist electrolyte paste. The gas pressure eventually rises to the point that the case ruptures and the capacitor explodes.

The part that opens the circuit is the overload blocks that are situated below the magnetic starter and before the motor load. The latest addition to the electrical code book states that the "hot" wire goes through the overload contacts first before feeding the 3 wire control system. With the supply voltage in this position the whole circuit becomes de-energized when the motor load trips the circuit.

The old standard practice on a 3 wire control system, the neutral was connected to the overload relay contacts. When the overload relay tripped it opened the neutral of the coil circuit and the starter dropped out

as far as i know recoil means change in the momentum of a particale, either by collision with another particale or radiation interaction.

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a transducer that converts sound to electrical signals

u mean potentiometer or a metre bridge ?

4 metre bridge R/X=L/(100-L)

Do you mean "can current flow in both directions"?

In theory, yes.

Power line carrier communications is used to provide high speed tripping for faults covering the entire power line.

On typical VHV and EHV systems, distance relays are used to protect the line in the event faults occur. Distance relays look at the impedance of the line (Voltage / current) to determine where a fault is. As one gets further away from the local end, the impedance will continue to grow. If one was to set distance relaying to look exactly to the very end of a line, it may or may not see the far end for all faults, due to errors in measurement of line impedance, error in the relay measuring, variances in system voltage, etc. Moreover, these errors may result in the relay seeing faults on the next line out (referred to as "overtripping").

Because of this, distance relays are typically set up in several zones - zone 1, which will be 80 - 90% of the line impedance, which is set to unconditionally trip; zone 2, which is set to 115% or more of the line impedance so it is garunteed to see the remote end.

Because zone 2 sees beyond the line, it must be conditionally controlled. This conditional controlling requires information from the remote end - specifically if the fault is "in front of" (on the line) or "behind" (on a different line) the remote relay.

And this is where power line carrier equipment comes in. On many lines in remote locations, there isn't a whole lot of fiber or microwave type communication equipment available. So signals are directly injected onto the powerline to pass the above information back and forth.

On some power line carrier equipment, there is also the ability to inject voice, so the same equipment can be used for communication between technicians at different substations.

Fiberglass Reinforced 4

Do you mean why is the voltage in a circuit lower after the light bulb than before it? If so, it's because the light bulb filament has electrical resistance. When an electrical current flows through a resistance, there is a voltage drop across the resistance (Ohm's law).

More fundamentally, the light bulb is producing light, which is a form of energy. The voltage drop across the light bulb comes from the fact that electrical energy is being turned into light. If voltage didn't drop, you would be producing energy from nothing. Furthermore, if there were no voltage drop, your circuit would behave the same whether you had no light bulbs, one light bulb, or eighteen million light bulbs - something that clearly can't be the case.

Polarity

electronic wave

The ultimate measure of power is the Watt.

to make things easier, sometimes 1,000 watts will be called a Kilowatt and 1,000,000 watts will be called a Megawatt.

Some industries like the Aluminum Industry on the Columbia River get their power from the Bonneville Power Administration by what is called "demand metering". Essentially they contract for a precise amount of energy during specific periods of time. A special meter that creates a "pulse" as each unit of energy is consumed allows the Aluminum Company to tune its furnaces to consume just enough, but not too much power. This is an example of a special way to deliver large amounts of power that benefit the industry as well as the power supplier.

A music producer is ultimately responsible for the sound of the finished product (or perhaps more correctly, their earsare). They manage and direct the project while the audio engineers do the "hands-on" work, making changes to the mix that the producer calls for.

A DC motor generates power when it is rotating even when no supply is connected.

The easiest way would be to convert the AC power to DC by using a rectifier diode and a filter capacitor. In that way you can now run your DC motor on DC.

Basic defect - it ceases to insulate between its two terminals and passes current that it should not.

Short circuit - the insulating material (dielectric) has failed and is allowing the two metal "plates" to come in contact. Depending on the circuit, effects range from simple loss of performance to failure to operate to destruction of other components. Easily detected by lifting/disconnecting one lead and measuring resistance.

Leakage - less severe than a short circuit, but the capacitor is allowing current to flow that should not. Usually an internal fault (partial failure of dielectric), but a faulty case may cause leakage, and other components connected to the capacitor may be the cause, making the capacitor appear faulty. Less likely to cause damage than short circuits, but severe leakage may cause other damage, moderate leakage may cause lack of performance or stop operation altogether. Some circuits are highly sensitive to leakage even if it is less than microamps (millionths of an amp). Resistance measurements will often help but (i) the leakage may only be apparent with considerable voltage applied - more than common meters do, and (ii) some types, especially electrolytics, exhibit leakage from new, so you need to know how much is acceptable.

Open - the capacitor does not allow any signal to pass. The most common symptom is loss of operation/ loss of performance, but some circuits can suffer damage if the capacitor is a critical part of its operation. Resistance measurements are of no use, so you need to use a capacitance meter or test by replacing with a good capacitor. If the new one fixes the problem, you've found the fault.

Intermittent - may be open or shorted. Intermittent leakage is possible but much less common. Tuning capacitors with moving plates often suffer intermittent shorts due to dust/metal fragments or bent plates (shorts), or faulty grounding "wipers" that have oxidised (rusted) or gotten greasy/dirty (opens). Tuning capacitor shorts can often be confirmed by inspection or resistance measurement, opens by inspection/cleaning.

Drift - the capacitor's actual capacitance increases or decreases, usually slowly, to a point where the equipment no longer works as designed. Observing equipment performance may confirm this fault, if not then measurement will be needed. Drift may happen with excessively high or low operating temperatures, and the equipment may work perfectly in the service shop at normal room temperature.

both of these components connected in parallel will cause an oscillation of energy, meaning the capacitor will charge and then discharge through the inductor , which will then build up a magnetic field and discharge through the cap again , and this oscillation will go on for quite some time and then finally die out , and also if a multimeter is place across the cap it should short out , because it's as if you have connected a piece of wire right across it ...