Miyerkules, Oktubre 12

Two Basic Types of Electricity


Static Electricity is an accumulation of electrical charges on the surface of a material, usually an insulator or non-conductor of electricity. There is no current flowing as there is in alternating current (AC) or direct current (DC) electricity. Static Electricity is simply electricity that is standing still - voltage potential with no electron flow.

Typically, two materials are involved in static electricity:

1. It has excess electrons or negative (−) charges on its surface
2. It also has excess positive (+) electrical charges
If one of the materials is an electrical conductor that is grounded, its charges will drain off immediately, leaving the other material still charged.

Static Electricity Sparks

An Electrostatic Discharge (ESD) or sudden flow of electric current across an air gap, heating the air to a high temperature, causing it to glow. The size of the spark depends on the separation of the sources of electrical charges and their potential difference in voltage.

Static and Environmental Condition

Dry Air:
Static electricity is formed much better when the air is dry or the humidity is low. When the air is humid, water molecules can collect on the surface of various materials. This can prevent the buildup of electrical charges.

When there is extreme turbulence among water drops, such as in a thunderstorm cloud, static electricity charges can build up on the water drops. Static electricity in created in a thunderstorm cloud.

Static Electricity Shocks

A static electric spark will jump from one material to another when the difference in the amount of positive (+) and negative (−) charges is sufficient to cause electrons to overcome the resistance of the air gap between the two materials.

The electrons heat the air for a fraction of a second, causing the spark and zapping sound.

Applications of Static Electricity

1. Pollution Control:
Factories use static electricity to reduce pollution coming from their smokestacks. They give the smoke an electric charge. When it passes by electrodes of the opposite charge, most of the smoke particles cling to the electrodes. This keeps the pollution from going out into the atmosphere.
2. Air Fresheners:
These devices strip electrons from smoke molecules, dust particles, and pollen in the air, just as what happens in creating static electricity
3. Xerography:
One version of this device electrically charges ink so that it will stick to the paper in the designated areas. Another version of a photocopier uses charges to stick the ink to a drum, which then transfers it to the paper.
4. Painting:
Put charge on the paint material and material to be painted, then spray a fine mist of paint into the material. The charged paint particles are attracted and stick on the painted material.

Risk with Static Electricity

1. Damages electronics parts
2. Trigger gas / fuel / dust explosion

Grounding Prevents Shocks and Sparks

Drain the electrostatic charge to ground, using a grounding wire.

Reduce Static Risk / Hazard

1. Increase Humidity
Static electricity is more active when the air and materials are dry. The humidity is normally lower in the winter, and heating the house further reduces the humidity.
2. Moisturize Skin
Some people have very dry skin that may cause the buildup of static charges, especially in the winter. One thing to try is to use moisturizers or lotions on your skin.
3. Clothes
Some clothing materials, such as polyester materials, cause more static electricity than others when they rub against your skin. Wear 100% cotton or wool clothing.


Dynamic Electricity is electricity that is in motion - voltage potential with electron flow.

Two types of Dynamic Electricity exist:

1. Direct Current
Direct current (DC) is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. A term formerly used for direct current was galvanic current.

Electrons are flowing only in one direction.
2. Alternating Current
AC is the form in which electric power is delivered to businesses and residences. The usual waveform of an AC power circuit is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. In these applications, an important goal is often the recovery of information encoded (or modulated) onto the AC signal.

Electrons flow alternately in both directions.

AC electricity alternates back-and-forth in direction 50 or 60 times per second, according to the electrical system in the country. This is called the frequency and is designated as either 50 Hertz (50Hz) or 60 Hertz (60Hz).

Advantages of AC Electricity

The major advantage that AC electricity has over DC electricity is that AC voltages can be readily transformed to higher or lower voltage levels for distribution. Changing voltages is done by the use of a transformer. This device uses properties of AC electromagnets to change the voltages.


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Commissioning Engineers

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