Electrical Engineering

In an alternating current circuit the voltage can be stepped up ordown efficiently with a transformer.

1,000,000V is not a measure of power. You need the amperage in the equation to figure out the power (wattage).

W = A x V

Yes a 208 voltage motor will operate on 220 volts. You have to increase the motor overload protection by 10% of the motor's full load amperage to protect the motor.

That is called a fuse.

A fuse is a protective device, which will interrupt the flow of electricity if it is subjected to a current that is greater than its rating.

Some fuses are designed to handle a large inrush of current and are used in circuits such as air conditioners, where a large amount of current is needed at startup, for a short duration and then current drops to a lower level.

These are sometimes called time-lag fuses.

negative tempareture

It depends on the reverse voltage. Up to about 5.6 volts, the zener has a negative temperature coefficient. Beyond 5.6 volts it begins to show a positive temperature coefficient.

A continuity test is a simple test, used to determine whether there is a break in a circuit. This can be done, for example, using an ohmmeter which passes current through the circuit from its internal battery -a deflection (analogue meter) or a '000' reading (digital meter) indicates that there is continuity. A continuity test MUST NOT be performed on an energised circuit, as this will likely damage the ohmmeter and present a shock hazard to the user.

For an insulating material dielectric strength and dielectric loss should be respectively

In order to pass DC current through a transformer you would need some basic knowledge of what a transformer actually is.

A transformer is simply put a coil of copper wire around metal plates of iron.

When you put current onto the coil, the metal plates will build up a magnetic field.

During the build up of this magnetic field, the current will be 'low'

When the magnetic field is maximized, the coil will work as a shortcut on a DC power source.

In order to use a transformer, ie transform voltage up or down, we need a fluctuating magnetic field. This can not be done without electronics of some variety, and the resulting voltage will be AC, not DC.

The easiest way to use a transformer with a DC power source is to make a circuit that electronically change polarization of voltage back and forth. Depending on transformer, this can be as low as 50 times per second (EU standard 50 Hz AC 220 Volt, US standard 60 Hz AC 115 Volt) or higher like 100.000 times per second (100 Khz) as is in many high speed switch power supplies. It all depends on the transformer you use and what you want to use it for.

If say you want to make a power source for an electric drill and you want to use a car battery as the source, then I would forget it. An electric drill need a lot of juice and in order to do so via a transformer, this transformer would need to be very very large.

Every ampere of 12 Volt would only give you approx 0.07 Ampere of 115 Volt.

A drill easily drain 800 to 1000 Watts. Approx 8 Ampere at 115 Volt.

Following this, an ideal transformer with hardly any loss would eat away 100 Ampere every 8 ampere on output 115 Vac.

With the loss factor (some of the transformed voltage will be given away as heat) and you would probably need approx 110 Ampere 12 Volt in order to generate 8 Ampere 115 Vac. A normal 60-65 Ampere car battery would then last a mere half hour fully charged. Another problem is that most batteries are not designed for such a load over any prolonged time (more than 30-60 seconds).

Systems have been and are buildt that can withstand such a drain but they consist of many batteries connected in paralell in order to even the drain between all batteries.

Currently, the transmission of electrical power from bulk power generators all the way to household, commercial and industrial consumers is made through high voltage alternating current (AC) transmission and distribution systems, and through a series of voltage transformations to reduce losses and minimize cost. Voltage levels used are of standard values.

AC system is used in the transmission of bulk power, instead of DC (Direct Current), because of its ability to transform voltage to various levels by using a transformer. The voltage transformation follows the faradays Law which states;The emf induced in a circuit is directly proportional to the time rate of change of magnetic flux through the circuit.

Note that, at higher voltage, the current was reduced thus line losses was also reduced.

Ability to transform voltage and to flow power in two opposite directions (bidirectional) are the only advantages of AC system over DC system.

DC transmission system on the other hand has more advantages over AC transmission system:

1. Reactance.

DC system does not introduce a reactance in the line.

2. Resistance

DC system reduces the amount of resistance in the line.

3. Power

In DC system, the power is just the real component.

4. Frequency

In DC system, the frequency is zero, thus no frequency variation to monitor. Connection will not also require synchronization.

5. Susceptance

DC system does not introduce susceptance in the line thus removing the effect of charging current.

6. Analysis

Analysis of AC system always involved complex numbers, while DC is only a real number, thus simplifying the analysis.

7.Number of conductors.

A DC system requires only two conductrs as compare to three for ac system.

8.Absence of inductance.

A DC system has no inductance as a result the voltage drop in DC system is less than that of AC system for same load and sending end voltages and hence a better voltage regulation.

9.NO skin effect.

A DC system has no skin effect so we can utilize entire cross section area of line conductor.

10.Less insulation require.

A DC system require less insulation than an AC system because of less potential stress for same working voltage.

11.absence of capacitance.

Absence of capacitance in DC system leads to less power loss because there will not be charging and discharging of capacitance.

If DC system has the ability to transform voltage into various levels, efficiently, the DC transmission system will the more efficient, stable, easy to monitor, and most importantly, easy to analyze than AC system.

Currently, the transformation of DC voltage into another level involves 3 steps;

1. AC to DC Rectification

2. AC to AC transformation, and

3. DC to AC Conversion

If compared to AC system voltage transformation, steps 1 and 3 are the only added steps. Unfortunately, these steps incur additional heavy losses. However, modern technology converter/inverter has attempted to reduce the amount of this loss. A 1000 MW, 230 KV AC - 450 KV DC/ 450 KV DC - 230 kV AC converter/inverter, for example, has a combine power loss of around 1.6 %.

The use of DC system in the transmission of power will be more economical if the price from its benefits is higher that the cost incurred from the addition of rectifier and converter.

It is very hot. The answer is 29726.85 C (approx.). The Kelvin scale starts at absolute zero and is used in scientific laboratories. Celsius is for general use and set 0 and 100 as melting and boiling point of water respectively. To convert from K to C, subtract 273.15 from K.

That depends on the unit. Normally mineral oil, sometimes silicone or wecosol, sometimes askarel.

Yes they can. There are regulations that cover most jurisdictions regarding how different cables can be contained. It is important that you are knowledgeable about your local requirements before starting the work.

IEEE stands for Institute of Electrical and Electronics Engineers. It is an organization made up of engineers, scientists and students who develop standards for the computer and electronics industry.

No, you definitely cannot.

The root word comes from the Latin, and means 'to lead'. The 'duct' part is the 'lead' part, and we meet it in conducive, conduct, duct, ductile, and so on.

Conductors are used to transfer energy or a material from one place to another. We have conductors for heat, sound, vibration, electricity, and so on.

A word with the opposite meaning is 'insulator'.

as frequency is reduced current gets increased winding gets heated.current goes up.voltage gets dropped.power also gets dropped.

No reason that I know of - assuming you are no longer being shocked.

It could depend on the severity of the shock though. With high voltage electrocution comes burns, and often the burns are internal. If the voltage passed through your gastrointestinal system, adding anything to it, even something as innocuous as water can cause greater issues.

Open Circuit test is done to find out core losses of the transformers.which include Eddy Current Losses and Hysteresis Losses only, if during open circuit test secondary will have some load then I2R losses due to load current in secondary as well primary will be included in test results which is not desired while performing Open circuit test.

The short answer is you need power. And power is the product of voltage and current: P = V*I. As either V or I approaches zero, P approaches zero. So, you need voltage and current flow to generate the power needed to operate an electrical circuit.

Yes, that's because the voltage output of an alternator is restricted by the number of windings that can be slotted into its armature, restricting its output voltage to just 25-30 kV, which is far too low for transmission purposes.

power factor correction, and sometimes it is necessary to place capacitors in series with a line to counteract the natural inductance of the line - this allows more power to be transferred through that line.