# Power Engineering concepts explained through informative GIFs

Power engineering is a branch of electrical engineering that deals with the generation, transmission and utilization of electric power as well as the electric devices connected to such systems. Though most of this field deals with problems of three-phase AC power but it also covers the fraction that deals with the conversion between AC and DC power. Electric power is the mathematical product of two quantities: current and voltage. These two quantities can vary with respect to time (AC power) or can be kept at constant levels (DC power).

### 1) Hydropower:

The energy derived from falling/running water and harnessed for useful purposes is termed as hydropower. A hydropower plant is shown which conducts electricity from the hydropower plant to homes and businesses.

### 2) Renewable Electricity

Electricity generated from sources which are naturally replenished such as solar energy and wind energy which can be easily used as a source for renewable electricity purposes.

### 3) Electric generator

An electric generator converts the mechanical energy into electric energy as shown in the given gif. The burning coal produces steam which is then converted into electricity using turbine generators and then supplied to households.

### 4) Transformer

An electrical device that transfers current through circuits using electromagnetic induction.  An alternate current passing through primary coil creates a magnetic flux which leads to induction of alternating flux into the secondary coil as well. The magnetic flux induces a voltage in the secondary coil thus lighting up the bulb.

### 5) Alternating current

The type of current that keeps on changing directions during its flow. It periodically reverses direction that is why it is termed as alternating current. The picture is an analogy of generating AC in which we connect a mechanical crank to a piston that moves water in the pipes back and forth (“alternating” current). Notice that the pinched section of pipe still provides resistance to the flow of water regardless of the flow direction.

### 6) Direct Current

The uni-directional flow of electric charge is termed as direct current. Direct current was previously known as galvanic current. It is usually produced by batteries, solar cells or electric machines of dynamo type. The picture shows a 12 volt battery as the source of the electric charge.

### 7) Three phase power

It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. A three-phase system is usually more economical than an equivalent single-phase or two-phase system at the same voltage because it uses less conductor material to transmit electrical power.

### 8) Inverter

The animation shows the the topology of a three-phase inverter which consists of  3 legs; each leg includes a switch in either the up or down position. The resulting eight possible switching configurations give rise to 6 active voltage space vectors and 2 zero vectors. The animation shows a specific sequencing of the 8 states where the active vectors rotate in discrete 60o steps.

### 9) Variable-frequency drive

A variable-frequency drive or VFD eliminates the initial power surge and mechanical shock of switching the motor from off to 100% on. A VFD changes the speed of an AC HVAC pump by varying or adjusting the frequency and voltage. In comparison, a DC motor speed is adjusted by only varying voltage. The picture illustrates that since the high frequency output will be the same as that of the input and it will not be possible to regulate the motor speed. But by switching from AC to DC and then again converting to AC, the variable frequency drive (VFD) will generate a frequency above the input frequency thus helping in regulation.

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