Table of Contents
Definition of Switch Gears
The devices used in switching, regulation, and protection of electrical circuits and equipment are installed in a panel board; these are collectively called switchgear.
or
switch gear meaning
“The apparatus used for switching, Controlling and protecting the electrical circuits and equipment is known as Switch gear”
Mainly switch gear equipment is related to switching and interrupting the current under normal and abnormal conditions.
In the operation of any electrical system, various types of switching devices are required to connect or break its electrical circuit as per requirement.
As–
For 0 – 25 Volt – use key.
For 50 – 250 Volt – normal switch (tumbler switch, flush type, bed switch, single shell switch etc.)
For 250 – 650 Volt – DPIC and TPIC switches etc.
650 -1000 Volt – Knife Switch
For 1000 – 33 KV – a Power Isolator and Triple Pole Manually Operated (T.P.M.O) and Circuit Breaker are used.
Introduction
From the production of electrical energy to its utilization, various types of auxiliary devices and equipment are used. We can use electrical energy with maximum efficiency only by continuous operation of these devices, but due to their continuous operation and some external reasons, it is natural for faults to arise in this system. To prevent faults arising in this way, it becomes necessary to use switch gear (fuses, circuit breakers, lighting arresters, and protection system relays, etc.) to keep the operation of the electrical system safe.
Generally, the fault that occurs in the electrical system is a short circuit fault, which generally occurs due to the failure of the insulation. The life of any machine or equipment depends on the strength of the insulation, the main reasons for the failure of the insulation are as follows.
(1) Mechanical damage/loss to equipment and devices.
(2) Decrease in dielectric strength or degradation of the dielectric material.
(3) In case of emergency arising directly/indirectly from overvoltage, overcurrent, lightning stroke and surge of equipment or devices.
Purpose of Protective switch Gears
The objectives of protective mechanisms to keep the electrical system safe are as follows:
- It facilitates connection and disconnection of electrical generating stations, transmission lines, distribution systems, utility equipment and other electrical equipment
2. Detecting faults in the electrical system with the help of protective gear and isolating the faulty section to localize the fault and help in protecting the system.
3. It facilitates inspection, maintenance, repair and supervision of fault conditions within the power system.
Elements of Switch Gears
The main components of switch gear are as follows-
(1) Installation element- It includes channel board, switch board, etc.
(2) Switching element- It includes switches, isolators, circuit breakers, etc.
(3) Regulation element
(4) Protective element
(5) Measuring element
Classification of Switching Gears
On the basis of structure switch gears are as follows-
(A) Indoor type switch gear
(B) Outdoor switch gear
Indoor type switch gears
(i) Cellular switch gear
(ii) Cubical switch gear
(iii) Track switch gear
(iv) Metal clad Switch gear
Cellular switch gear
Cellular Switch Gear – Such switch gear has its components located inside the building, it is brought to the site and installed with the help of bolts, their installation cost is low.
Cubical switch gear
Cubical Switch Gear – The components of such switch gear are fitted in a cubicle made of steel sheet. This cubicle has fully or partially separators fitted in it. Its complete adjustment is available readymade in the factory, hence there is no difficulty in installing it on the spot.
Track switch gear
Truck Switch Gear – Its entire unit is a moving piece on which movable contacts of circuit breaker, isolator, current transformer and potential transformer are mounted.
This is a modern complete switchgear unit. Its safety factor is high.
Metal clad Switch gear
Metal Clad Switch Gear – Here all the conductors and insulators are enclosed in a grounded metal casing. These are of two types-
(1) Horizontal draw out
(ii) Vertical drop down
This type of switchgear can be easily installed at site.
Outdoor Switch Gear
Such switch gears, which are installed outside in the open environment, are called outdoor switch gears. Their maintenance and repair take less time, but they occupy more space.
Functions of Switch Gear
The functions performed by the switch gear are as follows-
(1) Identification of the defective part by protective devices and automatic separation of the defective point from the rest of the part.
(ii) In case of short circuit faults, isolate the faulty part before the current value reaches dangerous limit.
(iii) To simplify the maintenance, inspection and redistribution of load of the power system.