Types of Insulators Used in Transmission Lines | Insulators Applications

What Is An Insulator?

In this article explain about What is an Insulator?, Types of Insulators, where can we use the insulator and their applications we will discuss in this article. an insulator is non conducting material which does not flow electrical current through this material called an insulator. Some examples of insulating material are paper, glass, plastic and air and also vacuum is an insulator, but it is not physical material. Insulators are generally rated at hundreds of volts, but in-case of power distribution systems are rated as high as hundreds of thousands of volts. Most electrical conductors are covered by insulation which are transformer winding wire is coated with extremely thin layer of insulation for more turns. Insulators in all applications mainly used for support and keep electrical conductors from making accidental contact each other.

Types of Insulators Used in Transmission Lines

The insulators are broadly classified into different types and rating based on their purpose. These insulators used in both transmission and distribution system so each insulator having several insulating discs. For example one disc used for 11kv voltage.

There are several types of insulators used in transmission lines for overhead insulation they are,

• Pin Insulator
• Suspension Insulator
• Strain Insulator
• Shackle Insulator
• Post-Insulator
• Stay Insulator
• Disc Insulator

Pin Insulator

Pin Insulator designed with a high mechanical strength material this kind of insulator is used in electrical distribution systems. This type of insulators are developed for overhead lines, pin type insulator commonly used in power networks voltage up to 33kv. Here pin insulator can be divided into three types such as one part, two part and three part type insulators depends on voltage application.

 

Pin Insulator

One part type Insulator: This insulator generally used in a 11kV system where whole pin insulator is one piece of properly shaped glass or porcelain material.

Two part type Insulator: This insulator generally use for 33KV system but in higher voltage systems – like 33KV and 66KV – manufacturing of one part porcelain pin insulator becomes more difficult.

Three part type Insulator: This insulator suitable for higher voltage rating applications up to 66KV systems.

Suspension Insulator

Suspension Insulator similar to the disc insulator and the designing of this insulator can be done using porcelain or glass. It is used in overhead transmission lines by ensuring more flexibility. Suspension insulators provides for higher voltage rating, beyond 33KV and up to 765KV transmission lines, it becomes uneconomical to use. In case of one of the insulator gets failure then remaining all the discs will works properly. So we can change the damaged disc easily.

Suspension Insulator

Rated System Voltage	Number of disc insulator used in suspension insulator string
33KV	3
66KV	4
132KV	8
220KV	14

 

Strain Insulator

A Strain Insulator is designed to work in mechanical strain (tension), to withstand great tensile load of conductor or strain. They are used in overhead transmission lines at dead end or there is a sharp corner in transmission line has to withstand to tensile load of conductor.

Stain Insulator

 

Rated System Voltage	Number of disc insulator used in strain type insulator
33KV	3
66KV	5
132KV	9
120KV	15

Shackle Insulator

The shackle insulator is generally used in low voltage distribution network. It is also known as a spool insulator it can be used in both horizontal or vertical positions. Shackle insulators are small in size and used in overhead distribution systems.

Shackle Insulator

The shackle insulator Voltage capacity is 33KV and it works in bend or circular turn positions. Now a days in low voltage distribution lines these insulators used as strain insulators for cost reduction.

Post Insulator

Post Insulators are similar to Pin insulators, the mechanical strength of this insulators are high. The post insulators are most suitable for high voltage rating applications. It is suitable for lower voltage and also for higher voltage

Stay Insulator

Stay Insulator is very small in size as compared with other Insulators, these are in rectangular shape and is used in the distribution lines. This insulator used only for low voltage lines and the stays are to be insulated from ground its acting like a safety device and that protection against sudden voltage changes.

Stay Insulator

 

 

Disc Insulator

Disc insulators are widely used in high voltage transmission and distribution systems, which are designed for providing electro mechanical strength. These insulators are provides a cost effective and medium or low polluted conditions and which are designed with high grade raw materials. The advantages of disc insulator include transmission lines, commercial distribution because it has high efficient like low corrosion, robust design.

Disc Insulator

Parallel Plate Capacitor | Parallel Plate Capacitance with Dielectric

Parallel Plate Capacitor

Parallel Plate Capacitors are an arrangement of two metal plates which are electrodes and insulating material or dielectric material both plates are separated from each other by some distance there is a dielectric between them. This dielectric medium is a separator for the plates which occupies the gap between the plates as shown in fig.

 

Parallel Plate Capacitor Diagram

The Capacitor is a passive component and it stores the electrical energy into an electrical field. The effect of the capacitor is known as a capacitance

In parallel plate capacitors used as dielectric medium such as air, vacuum, mica, porcelain, glass, paper wool, electrolytic gel and some other non conducting materials.

Working Principle of Parallel Plate Capacitor:

We know that the dielectric material does not allow the flow of electric current through it why because its non conductive property. If we can give a certain amount of charge to a plate and also supply more charge, the potential energy increases and it can be lead to leakage in the charge. In that case if we get another plate and place it next to this positively charged plate, then negative charge flows towards the side of this plate which is closer to the positively charged plate.

•  As both the plates have charges, the negative charge on plate 2 will reduce the potential difference on plate 1.
• On the other hand, the positive charge on plate 2 will increase the potential difference on plate 1.
• But the negative charge on plate 2 will have more impact.
• So, more charge can be given on plate 1. Because of the negative charges on plate 2 the potential difference will be less
• This is the principle of the parallel plate capacitor

Parallel Plate Capacitor Formula:

Q ∝  V

Therefore, Q = (constant)×V = CV

Where C = Capacitance of the capacitor; Q = Amount of charge stored in one capacitor; V = Potential difference between the two plates.

$C=k{ϵ}_0\frac{\mathrm{A/}}{d}$

Where, ε = permittivity of the medium, A = overlapping plate area and d = distance separation between the plates.

Types of Capacitors:

The different types of capacitors are following.

1. Electrolytic Capacitor
2. Mica Capacitor
3. Paper Capacitor
4. Film Capacitor
5. Non-Polarized Capacitor
6. Ceramic Capacitor

Electrolytic Capacitor

Electrolytic Capacitors are most widely used when large capacitor values required. Generally the thin metal film is used for one of the electrode and other for cathode electrode which is semi liquid electrolyte solution and which is in jelly or paste is used. Usually the dielectric plate is a thin layer of oxide, it is developed electrochemically in production with the thickness of the film and it is less than the ten microns.

Mica Capacitor

Mica Capacitors are more reliable capacitor and relatively small in size, this mica capacitors are used in small electronic pcb’s. Mica capacitors made by group of natural minerals and the silver mica capacitors used as dielectric medium. There are two types of mica capacitors which are clamped capacitors & silver mica capacitor. Clamped mica capacitors are considered obsolete due to their poor quality. Silver mica capacitors are made by sandwiching a metallic mica sheet on both sides and then the set is coated with epoxy to protect the environment.

 

 

 

Metal Detector Circuit using IC 555 timer Circuit

Metal Detector Circuit

A Metal Detector circuit is made by using IC 555 timer a common device used to check people, luggage, or bags in shopping centers, hotels, cinemas, etc., to ensure that a person does not carry metal or illegal things, like cannons, bombs, etc…

IC 555 Timer Pin Diagram:

Generally, this IC 555 Timer discover by “Signetic Corporation” and is denoted with SE or NE555 timer. Generally, it is used for timing circuits which gives highly stable time delays or oscillation. These ICs are very economical and reliable in cost compared to OP-Amp applications in the same manner.

555 Timer Applications:

• These 555 timers are used as astable and monostable Multi-vibrators in digital circuits.
• DC-DC converters
• Used in tachometers.
• Analog frequency meters.
• Voltage Regulators.
• Temperature control and measurement devices.

Metal Detector circuit

 Metal Detector circuit is frequently found at airports, theatres, and various other public places. They are used for the safety of people to detect anyone carrying a metal. In this project, we are going to design a  metal detector circuit. There are so many metal detector designs but most of them are complex in design so here we are going to design a simple metal detector circuit using 555 Timer IC.

How to Make a Powerful Metal Detector Using BC547 Transistor:

The above circuit shows a schematic diagram of the Metal Detector. IC 555 timer here it acts as a generator and generates rectangular wave pulses with audible frequencies for humans. The capacitor between terminal 2 and terminal 1 should not be altered as necessary to generate the sound frequency.

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Working of Metal Detector Circuit:

1. The 555 IC is wired as a Monostable multivibrator.
2. A monostable multivibrator is characterised by giving a high output when there is a low pulse signal to the input trigger pin.
3. The duty cycle of the output pulse from IC 555 is proportional to the Inductor L1 and Capacitor C1 which is connected in series to the trigger pin of IC 555.
4. Here the inductor we use is an Air core. When current flows through the Inductor a magnetic field is proportional to the current flow that develops around it.
5. This magnetic field senses when metal is brought near the inductor its inductance increases. This results in an increased inflow of current and the Capacitor starts charging quickly.
6. Feeding the trigger pin of IC 555.