Electrical Engineering

1 megohm is 0.1 gigaohm.

1 gigaohm is 1000 megaohm.

1 megohm = 1,000,000 ohms = 106 ohms.

1 gigaohm = 1,000,000,000 ohms =109 ohms.

The secondary winding's current rating is the rated apparent power of the transformer (expressed in volt amperes) divided by its voltage rating (expressed in volts). This applies to both step down, and step up, transformers.

The more coils you have on one side will increase the magnetic force

What you may be referring to, since the question was posted in electrical engineering section, is in reference to the electrical switches and devices installed on sprinkler systems. The systems have water flow devices, low air switches, valve tamper devices and the like. each device is designed to monitor changes in state in the system. (sprinkler waterflow, low air pressure in a system, an improperly open or closed valve, to name a few.) these devices are designed to send an electrical current or signal of high or low voltage to a device(bell or siren) or to an alarm or control panel. The terminals on these devices are similar. They have a "common" terminal. Next, they have an "normally open" terminal; which means the circuit is open normally, but closes during a change in state. The circuit is supervised with a end of line resistor in the circuit, hence an "open loop"

If the ratio of voltage to current is constant, then the circuit is obeying Ohm's Law. If the ratio changes for variations in voltage, then the circuit does not obey Ohm's Law.

Simply multiply the peak voltage to 2 and you will get the peak to peak voltage.

For any given load, the higher the supply voltage, the lower the resulting load current. A lower load current results in an acceptable voltage drop along the line, that conductors with lower cross-sectional areas can be utilised, and line losses are minimised. So high voltages are essential for energy (not 'power') transmission.

MODEM stands for modulator/demodulator. Outgoing it modulates a carrier wave with information and transmits this data on a wire or through the air. When it receives a modulated signal it demodulates the signal and separates out the information.

Voltages are produced by converting one form of energy into electrical energy. Mechanical energy can be converted into electrical energy (voltage and current) by moving a magnet or magnetic coil in proximity with a stationary coil, connected to an electrical circuit.

A voltage can also be produced with a chemical reaction. Batteries and fuel cells convert energy in specially designed cells, where a chemical reaction causes a voltage to exist across two electrodes implanted at two different parts of the cell.

A voltage can be produced by the interaction of light on a photocell. The photons of light interacting with atoms in the photocell, cause an electron to be ejected. The special design of the photocell causes this to occur in such a manner as to produce voltage across the cell.

A voltage can be produced by subjecting a thermocouple to differential temperature. A thermocouple is a relatively simple device composed of two dissimilar metals, joined together at what is referred to as a thermal junction. If one side of the junction is warm, relative to the other side of the junction, a voltage exists across the junction.

Many wonder what is the function of iron core transformer. The iron core in a transformer facilitates max flow of magnetic flux between primary and secondary windings. It result in inducement of the same voltage in both windings is possible.

A poor power factor is usually caused by coils; by inductors within electric motors. A capacitor is the opposite of a coil, and can improve the power factor by moving the current phase angle forward, more towards the voltage.

Power factor degradation from inductive loads occurs because inductors resist a change in current, by "presenting" a higher resistance to a step (or any) change in current. As a result, current lags voltage, and power factor suffers.

Capacitors are opposite to inductors. They resist a change in voltage, by "presenting" a lower resistance to a change in voltage. As a result, current leads voltage.

Suppose that a capacitor is placed in parallel to an inductor. If the value of capacitance is adjusted so it exactly cancels the inductance at 60Hz, then the combination as a whole behaves purely as a resistor.

If capacitive loads were common, then they would cause problems similar to inductors.

However, adding capacitance in a case where there is also inductance serves to raise voltage, particularly since the conductors (power lines, etc.) leading up to the load are also resistive, inductive, and partially capacitive. By raising the voltage, power factor is improved, and the inductive loads (usually motors) cause fewer losses in power lines.

to measure electrical enegy

Number of poles and supply freqency determines speed of synchronous motor.

For speed control of such motors Variable Freqency Drives(VFD) are used.

An earthing transformer provides a neutral in a delta connected system.

If you are talking about the field rheostat on a generator, once you have the correct voltage output set, it is very unlikely that it has to be touched again. If it is the generator's first start up, then it is best to set the field on the low side so as not to over excite the generator and drive the output voltage higher that what the generator's specifications are rated at. The field excitation voltage does not have to be set at the minimum position on every start up once it is set for the correct output voltage. A good example of this is a hospital standby generator, it starts up with no human intervention needed.

V = i*r

v = 2 * 60

v= 120v

V = I*R

R = V/I

If we fix the voltage at 1 then

R = I^-1

The change in the resistance scale is the derivative

R dr = I^-1 di

R dr = -I^-2

R dr = -1/(I^2)

Explanation:

The change in the resistance measurement decreases by the inverse of the current squared.

Alternating current is much more efficient to transmit than direct current. Using transformers, it can be stepped up to high voltages for transmission over long distances using relatively small conductors, and then stepped down at the destination to provide high current.

There's not a lot to go wrong in a transformer. You can test with an ohm meter (resistance meter) to check that the wires aren't broken if you know what the connections are. It will read low around 10 ohms if the wires are OK and will read very high if they aren't.

However there is a slight possibility that if it is damaged some of the wires may have shorted out so it will still read OK but will overheat when you put full power on it. So you need to power it up and check the output is what it should be with a voltmeter set on AC for a suitable scale.

Be careful not to electrocute yourself.

A change in current through an inductor will induce a voltage into that conductor, the direction of which will always oppose that change in current. This is a natural phenomenon due to the conservation of energy.

F.C. Kohli (Fakir Chand Kohli)

It is a safety measure for devices that have a metal case where a failure in the device could cause the case to be connected to the hot side of the circuit. By grounding the case the breaker will trip instead of you getting a shock.

American Samuel F. B. Morse introduced the first commercially successful telegraph in 1844

A closed loop system for the purpose of feeding back the output signal to the input side requires sophisticated sensors, which make this scheme expensive to implement. Initial tuning of the system is also difficult(feedback serves the purpose of fine tuning).

when the current is passing through the winding then it is called "Excitation".

Types of excitation

(1)seperately excited generator.

(2)self excited generator.

self generator is classified into 3 types.

1.shunt generator.

2.series generator.

3.compound generator.

compoud generator is again classified into 2 types.

1.short shunt generator.

2.long shunt generator.