A Short Note on Insulators

The materials or substances that resist or don’t allow current to pass through them are insulators. In other words, they hinder the flow of electrical current. Conductors are the opposite of insulators. Meaning to say, they allow free movement of electric particles. Insulators are usually found in our household items and electrical circuits. They act as protection from electrical current. They are, in general, solid in nature. Similarly, thermal insulation restricts heat flow instead of electricity flow. Resistivity is the property that makes insulators different from conductors.

Importance of Insulators

Insulators are of great importance as they help in keeping us safe from the hazardous effects of electricity and heat. When the electrons start moving, an electrical current takes place. The atoms in insulators have tightly bound electrons. Moreover, they are static thus, they do not keep moving throughout the material. Consequently, the current is not able to pass through the material easily. Thus, it prevents us from receiving an electrical shock.

Uses of Insulators

We use insulators in many ways. Most commonly, electric wires and cables have a coating of an insulator that is referred to as an insulated wire. Without an insulating coating, wires may touch other wires and create cross-connections, fire hazards, and short circuits. Thus, with an insulating coating, these problems can be prevented.

Some wires come with a mechanical covering having no voltage rating like a doorbell, service-drop, welding, etc. In an insulated wire, the voltage rating is present. Similarly, electronic systems and printed circuit boards are composed of fibreglass and epoxy plastic.

High voltage systems that contain transformers and capacitors use liquid insulator oil to prevent electrical breakdowns. Other materials for insulation include ceramic, glass, air, etc.

Good Insulators

The two types of insulators are electrical insulators and thermal insulators. The former one can trap electricity while the latter can trap heat.

The good insulators are wood, plastic, rubber, and ceramics. Glass is an electrical insulator but it is expensive. Thus, plastic replaced it. Moreover, there is lower resistance in plastic and it is also not that expensive compared to glass. It also serves well for the purpose of mass production. Further, we have the handles of cooking pans that are insulators.

When we cook something on our metal cooking pan, it conducts heat easily for cooking, but the handle remains cool and keeps us protected. It is because it is made of insulating materials such as wood, plastic, or rubber.

Other insulators commonly found in our homes are glass windows. They help in keeping the heat inside our homes. There are also special insulators present inside the walls that trap the heat to keep the room warm.

Types of Insulators

There are different types of insulators. The common ones are:

Pin Insulator

This insulator is mounted on a pin on the cross-arm of the pole. These types of insulators are great for transmitting and distributing communications and electric power. It can work for voltages up to 33 kV.

Post-Insulator

This one is more compact and a great alternative to the pin-type insulator. It can be used on lines up to 69 kV and sometimes even 115 kV.

Suspension Insulator

These types of insulators are used for voltages that are higher than 33 kV. It is composed of many glasses or porcelain discs that connect via metal links in a string form. In voltages higher than 33 kV, pin insulators are not an economical option because of their size and weight.

Strain Insulator

This electrical insulator has been made to work under mechanical strain. Thus, it can endure a suspended electric cable’s pull. Mostly, these types of insulators are used in overhead electrical wiring. They help in supporting radio antennas as well as overhead power lines.

Shackle Insulator

Earlier, these insulators came into use as strain insulators. Also called spool insulators, shackle insulators are now used for distribution lines with low voltages. They can be found in both horizontal and vertical positions. 

Bushing

It is a hollow electrical insulator that permits the passing of an electrical conductor through a conducting barrier without forming an electrical contact with it—for instance, a transformer or circuit breaker. In simpler terms, it allows one or more than one conductor to pass through a partition like a tank or a wall.

Classes of Insulators

We can classify insulating materials into seven classes. They are:

·  Class Y Insulating Materials – 90°C

·  Class A Insulating Materials – 105°C

·  Class E Insulating Materials – 120°C

·  Class B Insulating Materials – 130°C

·  Class F Insulating Materials – 155°C

·  Class H Insulating Materials – 180°C

·  Class C Insulating Materials – >180°C

Conclusion

The materials or substances that resist or don’t allow the current to pass through them are insulators. They are the opposite of conductors. The resistivity is the property that makes insulators different from conductors. The two types of insulators that can trap heat and electricity are thermal and electrical insulators, respectively. They are, in general, solid in nature. We use insulators in our daily lives, and they keep us safe from electric shocks and getting burnt.