Electrical engineering blog

elect 1.35
electoral 2.64
electret 1.95
electrical 0.92
electrically 1.46
electrican 0.64
electricans 0.5
electrician 2.17
electricians 1.56
electricista 0.5
electricity 2.33
electrics 1.36
electrified 1.48
electro 0.5
electrocardiografo 0.5
electrocardiograph 0.5
electrocardiographs 2.1
electrocautery 0.5
electrode 0.98
electrodes 0.86
electrodynamic 1.32
electrograph 0.5
electrol 2.59
electrologist 2.26
electrologists 0.5
electrology 0.5
electroluminescence 0.5
electroluminescent 1.44
electrolysis 0.54
electrolyte 0.93
electrolytic 1.11
electromechanical 1.5
electromotive 0.5
electronic 2.31
electronically 0.89
electronics 1.24
électronique 0.5
electrophoresis 1.39
electroplate 0.5
electroplated 0.54
electroplating 0.5
electrostatic 0.5
electrotherapy 1.39
eleele 3.08
elefant 1.12
elegant 1.31
elegante 0.5
elekronik 1.62
elektr 0.5
elektriciteit 1.62
elektriker 0.5
elektrikker 2.47
elektrisch 0.5
elektrische 0.88
elektrisches 0.5
elektrizitat 0.5
elektro 0.7
elektroautos 1.36
elektrobranche 0.5
elektrofilter 1.44
elektroheizung 1.43
elektroherde 1.93
elektromagnetisch 1.25
elektromotoren 0.5
elektronik 1.13
elektronikfertigung 2.29
elektronisch 1.56
elektronische 0.5
elektronischer 0.5
elektronisches 1.54
elektroniske 1.37
elektrotechniker 2.75
elektrotherapie 1.53
elektrowerkzeug 0.5
elementals 1.03
elementary 0.5
eleni 0.5
eleph 0.5
elephant 1.39
elettronico 0.5
eleuthera 1.91
elevadora 1.13
elevate 1.59
elevating 1.47
elevations 1.2
elevator 1.17
elevators 2.25
elexia 0.5
elgin 1.85
elh 0.74
elica 0.81
eligibility 0.92
eligible 2.49

Electrician Courses across the UK.
Gain electrical qualifications and have
a lucrative career as an electrician in months.

Did you know there is a small group of men and women in the UK (and most of Europe) who are quietly making a great living and frequently working only 2 - 4 days per week? With our electrician courses you could be one of these people.

Over the last year some of these individuals have been featured in the National Press, including The Times, The Observer and the Guardian newspapers - some of them have been on our electrical courses!

Starting from scratch with no knowledge, no special talents and often no capital they have gone on to create huge streams of income for themselves and their loved ones. We will give you the electrical skills and electrician qualifications you need for a career as a electrician.

Many people from all walks of life have successfully completed our electrical courses, and are now enjoying a lucrative career as a electrician.

The Electrical Career Skills electrician training course offers flexible learning. This means that you are in control of the electrical course. When you finish your electricians course, we will not just leave you to it, we will support you in finding a electrical job or becoming a self-employed electrician.

Please feel free to read through this web site, and then click on the Request Information link to find out more about our accredited electrical training courses.

http://www.forumelectric.com/Engineering.html

electrical engineering forums electrical engineer forum electrical engineering forum electrical forum elecrical engineering forum electrical engineer forums electrical forums como se produz energia elétrica nas centrais termoelectricaselectrical engineering schools electrical schools

A DC motor is designed to run on DC electric power. Two examples of pure DC designs are Michael Faraday’s homopolar motor (which is uncommon), and the ball bearing motor, which is (so far) a novelty. By far the most common DC motor types are the brushed and brushless types, which use internal and external commutation respectively to create an oscillating AC current from the DC source — so they are not purely DC machines in a strict sense.

The classic division of electric motors has been that of DC types vs AC types. This is more a de facto convention, rather than a rigid distinction. For example, many classic DC motors run happily on AC power.

The ongoing trend toward electronic control further muddles the distinction, as modern drivers have moved the commutator out of the motor shell. For this new breed of motor, driver circuits are relied upon to generate sinusoidal AC drive currents, or some approximation of. The two best examples are: the brushless DC motor, and the stepping motor, both being polyphase AC motors requiring external electronic control.

There is a clearer distinction between a synchronous motor and asynchronous types. In the synchronous types, the rotor rotates in synchrony with the oscillating field or current (eg. permanent magnet motors). In contrast, an asynchronous motor is designed to slip; the most ubiquitous example being the common AC induction motor which must slip in order to generate torque.

In power transmission and distribution, significant effort is made to control the reactive power flow. This is typically done automatically by switching inductors or capacitor banks in and out, by adjusting generator excitation, and by other means. Electricity retailers may use electricity meters which measure reactive power to financially penalise customers with low power factor loads. This is particularly relevant to customers operating highly inductive loads such as motors at water pumping stations.

The ratio between real power and apparent power in a circuit is called the power factor. Where the waveforms are purely sinusoidal, the power factor is the cosine of the phase angle (φ) between the current and voltage sinusoid waveforms. Equipment data sheets and nameplates often will abbreviate power factor as “cosφ” for this reason.

Power factor equals 1 when the voltage and current are in phase, and is zero when the current leads or lags the voltage by 90 degrees. Power factors are usually stated as “leading” or “lagging” to show the sign of the phase angle, where leading indicates a negative sign. For two systems transmitting the same amount of real power, the system with the lower power factor will have higher circulating currents due to energy that returns to the source from energy storage in the load. These higher currents in a practical system will produce higher losses and reduce overall transmission efficiency. A lower power factor circuit will have a higher apparent power and higher losses for the same amount of real power transfer.

Purely capacitive circuits cause reactive power with the current waveform leading the voltage wave by 90 degrees, while purely inductive circuits cause reactive power with the current waveform lagging the voltage waveform by 90 degrees. The result of this is that capacitive and inductive circuit elements tend to cancel each other out.

Engineers use the following terms to describe energy flow in a system (and assign each of them a different unit to differentiate between them):
Real power (P) [Unit: W - Watt]
Reactive power (Q) [Unit: VAR - Volt-Ampere Reactive]
Complex power (S) [Unit: VA - Volt-Ampere]
Apparent Power (|S|) [Unit: VA]: i.e. the absolute value of complex power S.

In the diagram, P is the real power, Q is the reactive power (in this case negative), S is the complex power and the length of S is the apparent power.

The unit for all forms of power is the watt (symbol: W), but this unit is generally reserved for the real power component. Apparent power is conventionally expressed in volt-amperes (VA) since it is the simple product of rms voltage and rms current. The unit for reactive power is the “var”, which stands for volt-amperes reactive. Since reactive power flow transfers no net energy to the load, it is sometimes called “wattless” power.

Understanding the relationship between these three quantities lies at the heart of understanding power engineering. The mathematical relationship among them can be represented by vectors or expressed using complex numbers,

(where j is the imaginary unit).

The complex value S is referred to as the complex power.

Consider a simple alternating current (AC) circuit consisting of a source and a load, where both the current and voltage are sinusoidal. If the load is purely resistive, the two quantities reverse their polarity at the same time, the direction of energy flow does not reverse, and only real power flows. If the load is purely reactive, then the voltage and current are 90 degrees out of phase and there is no net power flow. This energy flowing backwards and forwards is known as reactive power. A practical load will have resistive, inductive, and capacitive parts, and so both real and reactive power will flow to the load.

If a capacitor and an inductor are placed in parallel, then the currents flowing through the inductor and the capacitor tend to cancel out rather than adding. Conventionally, capacitors are considered to generate reactive power and inductors to consume it. This is the fundamental mechanism for controlling the power factor in electric power transmission; capacitors (or inductors) are inserted in a circuit to partially cancel reactive power of the load.

The apparent power is the product of voltage and current. Apparent power is handy for sizing of equipment or wiring. However, adding the apparent power for two loads will not accurately give the total apparent power unless they have the same displacement between current and voltage (the same power factor).

Electrical enginnering forum, electrician forum, power electrical software, electric forum, electrical forum, electric forums and electrical forums.