The insulator refers to a device whose prime function is to 'insulate'. An insulator is an electrical device that opposes the flow of current in a circuit. This quality of insulators to resist the motion of electrons is of great electrical advantage. They are often used as a protection device in certain circuits with high currents.
What is Insulator?
An insulator is a material that does not allow electricity, heat, or sound to flow through it. In other words, insulators are substances that do not allow electrons, sound waves or heat to pass through them. The electricity requires a flow of electric current hence the insulators are used to safeguard from the harmful impacts of the electricity.
Origin of Insulator
Ceramics and glass materials were the earliest devices used for making insulators. Soon it was observed that ceramic material didn't perform very well with time first non-ceramic insulator was polymer which was introduced to enhance the performance. Telegraph lines were the first electrical systems to put insulators in use. With the advancement, insulators have started to come in various shapes and devices and are made of different materials.
List of Common Electrical Insulator Materials
There are various insulator materials:
- Porcelain
- Glass Insulators
- Polymer Insulators
- Ceramic Insulators
- Rubber Insulators
- Mica Insulators
- Foam Insulators
- Silicone Rubber Insulators
Types of Insulators
The insulators can be divided based on their rating:
Pin Insulator
These insulators are generally used in distribution systems of electrical power. They can be oriented in vertical or horizontal alignment. These insulators require minimal maintenance. They typically consist of a groove to support the pin or the bolt.
Suspension Insulator
High-voltage transmission generally employs the use of suspension insulators. Materials like porcelain or glass are used for manufacturing them. The structure consists of a series of discs connected by a metallic link. Any breakage or damage in a single disc can be replaced by a new disc without destroying the whole link.
Strain Insulator
As suggested by the name these insulators are employed to handle the mechanical strain generated. It is placed in a bend or in between corners where the strain generated is greater. The design is similar to suspension insulator.
Shackle Insulator
Particularly small in size, shackle insulators are attached to a cross-arm to support the transmission lines. They are used in overhead distribution and their major characteristic is their U or V shape and their groove to hold the conductor.
Post Insulator
The post insulators are mechanically strong insulators commonly used in substations and indoor places. They have a vertical conductor connected to the top of the insulator.
Stay Insulator
They are commonly used to support the stay wires and provide additional support. These devices are particularly used to protect devices from sudden faults or voltage changes.
Disc Insulator
The characteristic of this insulator is their use in high-voltage transmission lines. They are a cost-effective method with minimum pollutants in the environment. The structure consists of several porcelain or glass discs connected in series by metal discs.
Types of InsulatorWorking of Insulators
We observe the energy band diagram of an insulator to understand its working:
Energy Bands in InsulatorValence Band: This is the outermost band, and electrons present in this band are valence electrons.
Conduction Band: When free electrons escape from their valence band, they get freed from the atom and enter the conduction band.
As seen in the diagram, we have a valence band that consist of the valence electrons, and we have a conduction band responsible for conduction. The forbidden energy gap is the minimum energy gap that is required to be crossed for electrons to transfer from the valence band to the conduction band.
For current to flow, the electrons need to gain sufficient energy to cross the energy gap and enter the conduction band after crossing the valence band. Inside an insulator like wood, the energy gap is quite big and therefore it becomes almost impossible to cross this energy barrier.
The depletion width is very large, and electrons can't cross this width thereby there is no flow of current. Unlike insulators, this gap is very low in conductors and electrons can easily cross the barrier causing good electron flow for current generation. Hence, insulators resist the flow of current.
Properties of Insulators
Some of the insulator properties are listed below:
- They have very high electrical resistivity thereby they resist the flow of current in electronic devices and prevent any current leakage.
- They have high thermal resistance meaning they maintain the temperature and other parameters of the circuit by preserving the thermal state in circuits.
- They have high mechanical strength. This property is used to talk about how much mechanical stress can they tolerate without breaking. The strength can be designed depending on the use of an insulator.
- They have high dielectric strength which helps them store electrical energy. They also have low permittivity.
- They are often mechanically strong devices with high strength.
- A rise in temperature can cause variations in the electrical properties of the insulator thereby we need to test resistors.
Advantages and Disadvantages of Insulator
Some advantages and disadvantages of insulators are listed below.
Advantages
Some of the insulator advantages are listed below:
- They are often used as thermal insulation devices. Due to their insulating properties, they are used to control the heat transfer from the device and maintain a certain equilibrium temperature.
- They are often used as safety devices to prevent electrical shocks from circuits. They isolate the conducting element ensuring no sudden shocks to individuals.
- By resisting the flow of current in unintended path direction they help to prevent any wastage of energy. This property is used during communication in transmission lines.
- Due to the good dielectric properties of some insulators, they can be used inside insulators where they act as a storage element and store the electric field.
- Insulators, in general, have multiple uses ceramics in fiber optics, glass, rubber, and plastics are common insulating materials and are employed in various daily use equipment.
Disadvantages
Some of the insulator disadvantages are listed below:
- It became very important to select an insulator with precision keeping in mind its threshold voltage. Insulators have a maximum voltage threshold beyond which they can break down and allow current to flow through.
- Insulating materials are not very adaptive to harsh environments. Due to this, they have short lifespan and may degrade with time reducing their efficiency.
- Synthetic-based insulators pose harm to the environment. Plastic which is a non-degradable insulator can be a serious threat to environment.
- They are not very robust to temperature variations. In extreme temperature conditions, insulators may show deviation from their properties.
Applications of Insulator
Some of the insulator applications are as follows:
- Thermal Insulator: Insulators are often seen for making thermoplastic bottles and fireproof walls and ceilings. This is because that insulators do not allow the heat to transfer from one point to another.
- Electrical Insulator: Insulators are often used to make motherboards, circuit boards and insulation of wires and cables due to the high resistance offered by them which hinders the flow of electrons in the electric circuit.
- Sound Insulator: Insulators are often used in the acoustics of buildings and lecture halls because of their noise absorption property. They are good absorbers of noise and help to control the noise level.
Difference Between Conductor and Insulator
The table below represents the difference between the conductors and the insulators.
| Characteristic | Conductor | Insulator |
|---|
Definition | Conductors are materials that allow electrons to flow through them. | Insulators are materials that do not allow electrons to flow through them. |
| Electrical Conductivity | Electrical conductivity is high. | Electrical conductivity is low. |
| Electrical Resistance | Electrical resistance is low. | Electrical resistance is high. |
| Flow of Electrons | It allows the free flow of electrons. | It restricts the flow of electrons. |
| Band Gap | Narrow or nonexistent | Wide |
| Examples | Copper, Aluminum, Gold | Rubber, Glass, Plastic |
| Applications | Wiring, Electrical Circuits, Conductive Elements | Electrical Insulation, Thermal Insulation |
| Heat Conductivity | Generally high | Generally low |
| Behavior in the Electric Field | Conducts electricity | Does not conduct electricity |
| Behavior at High Voltage | May suffer from high-voltage breakdown | Resists high-voltage breakdown |
Conclusion
From the above discussion we can conclude that the insulators are the materials in which electric current does not flow hence, it is used to prevent damage and adverse effects of electric current. The insulators are used for insulation, safety purposes etc. Insulators resist the current to prevent the current leakage.