Electrical Engineering

Low power factor means higher than necessary load currents. These require unnecessary expenditure on the amount of copper in supply equipment such as cables, transformers, and switchgear. Higher than necessary load currents also mean greater voltage drops and poorer voltage regulation.

220v, 415v, 6.6 kv, 11kv,33kv,132kv,400kv

Inside the generators junction box there will be termination points that the generator coils terminate on. On the inside of the lid of the junction box there should be a diagram for different connections allowed for that generator. By moving jumpers around across these terminals a variety of voltages can be obtained.

depending on kva class of the motor between 4-8 times the running current

No. The potential DIFFERENCE of a battery (or, more accurately, a dry cell) is 1.5 V.

208 v three-phase supplies are an option for American properties, because the line to neutral voltage is 120 v.

The phases of the moon take the same amount of time as it's orbital period, and a small fudge factor due to earths own orbit.

This results in the phases taking ~28 days to go full cycle.

There are 8 phases in total, meaning each phase lasts about three and a half days.

Silicon is useful as a base to build electronic components on because it has all the valence electrons it wants (4). A diode is created by placing a an element with an "extra" valence electron near an element that wants an "extra" valence electron.

Terminology gets misapplied but a 3-phase converter produces a 3 phase supply from a single phase supply. The only proviso is that generator, converter and motor are all suitably rated and compatible.

For power factor improvement so that the KVA demand is reduced.

1.devestator

2.fallen

3.kpu

4.optimus

5.megatron

6.starscream

7.ratchet

8.bumblebee

9.sideways

Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points, and inversely proportional to the resistance between them

Generally most A.C motors that most people see regularly have no commutator (though not all) ,so there is sometimes less mechanical frictional losses this can increase overall efficiency.

This usually means less parts to fail.

Some A.C motors require ¨start¨ and or ¨run¨ capacitors and may also require a start mechanism that will have frictional losses and add to the bits that could fail.

They also often have detrimental magnetic eddies which cause some losses, this is often due to economical stator or rotor construction.

A.C motors can have a very high power density as the magnetic flux is generated with an A.C current this can be higher than most conventional D.C. motors especially due to the high rate of change of current through the stator and rotor.

This is the very nature of the A.C current it is constantly changing.

D.C motors are often made using permanent magnets (again not always) so they can ¨get something for nothing¨ so to speak with an existing magnetic field. Energy does not have to be wasted to create one of the required magnetic fields to make the motor rotate.

D.C. motors can be made without permanent magnets too. Some of these motors can also have very high energy densities as the current can be made to change very rapidly either with the commutator or with special drivers.

There are very few hard and fast rules about A.C versus D.C in motors as both types have been extensively developed over many years.

The decision to use an AC or D.C motor usually come down to what is available to drive the motor in question.

Cars use D.C. as they have a D.C battery.

Washing machines and fridges use A.C as it is generally more efficient to send A.C over long distances to your home.

It is also currently far easier to convert A.C up and down through transformers etc, The transmission and distribution of D.C is far less efficient and more complex so this often dictates our choice rather than the motor type.

We deliver power on the power grid as an AC voltage. That's alternating current, and that's what is available in your home.

There is no minimum height specified by the NEC.

Transistors are typically operated in one of two (well, four) regions: saturation/cutoff or linear (forward or reverse).

When used as amplifiers, transistors are operated in the linear region. If you look at a transistor's V-I (voltage - current) characteristic, you'll see the linear region is somewhere "in the middle", where there is sufficient voltage applied (so current flows), but not to much (so the transistor is not saturated). To get transistors to operate in this middle region, DC circuits are used to bias the transistor to the center of the linear region. So the transistor is working on both AC (the signal applied to the input that is amplified at the output) and DC (the biasing network to allow the transistor to operate as a linear amplifier).

When used in saturation/cutoff, the transistor is being used as a switch (on/off). this is common in logic devices (gates, arrays, CPUs, etc.). The input to these devices is typically an irregular AC wave (a square wave of information). A power source is needed that is DC, however, to provide the power to drive the output to one state or the other.

So proper transistor operation requires both AC (as the signal) and DC (as the biasing network, or power source).

Resistor is an eletrical and electronical part whose function is to decrease the value of the voltage in a circuit, consequently reducing the value of the current, which is measured in Amperes.

7.5kVA is a value derived from the voltage multiplied by the current.

Without knowing one, you cannot know the other.

For example, think of the number 10kVA

This could be made by :10kV * 1A or 5kV * 2A or 1kV * 10A or 2kV * 5A.

You couldn't possibly know which is the initial pair.

Probably 2-3 HP.

<<>>

The electrical code book states for estimating values only that a 1.5 HP motor operating on three phase 208 volts draws 6.6 amps. For calculating overload protection and conductor size, the motors nameplate rating should always be used.

If you keep all of them in series, then each component in your circuit will have

more voltage across it and more current through it, and will dissipate more

power (heat).

If you keep all of the batteries in parallel, then they must all be rated for the

same voltage. Nothing about the circuit's performance will change, but it'll be

able to operate longer before the batteries die.

The current is the same in the three live wires. The voltage can be described as the line voltage (phase to neutral) or the phase voltage (phase to phase) which is larger by a factor of sqrt(3).

So a line voltage of 230 v corresponds to a phase voltage of 400 v.

Sorry. You cannot convert ohm-cm to Mohms, just like you cannot convert mph to miles. They are two different concepts.

If you also have the thickness of the material (say along the z axis) in question, then you can divide ohm-cm by the thickness to get to ohm per square. In order to convert ohm per square to ohms, you also need to know the number of squares (the x-y plane).

An example. Let us assume a metal ruler of two cm wide (x), one meter long (y), and 0.2 cm thick (z). Let us assume the resistivity of the metal is 1 ohm-cm. Find the resistance of the metal along the length of the ruler (in the y direction).

Resistivity = 1 ohm-cm

Thickness = 0.2 cm.

Sheet resistance = 1 [ohm-cm] / 0.2 [cm] = 5 ohms/square

Number of squares = 1 [m] / 2 [cm] = 50 squares

Total resistance along y = Sheet resistance * number of squares = 250 ohms.

Q.E.D.

P.S. Note that the term, resistivity, is a general property of the metal, no specific design in mind. Resistance is calculated for a specific object (the ruler) made of the metal. "Square" is not one of the SI units, but "Square" and "sheet resistance" are terms used by engineers to describe thin films.

============================