Government Engineering Collage Palanpur

Branch :- Mechanical Engineering

Subject Name:- Elements of Electrical Engineering (2110005)

Topic Name:- Safety & protection

Group No. :- 1

Enrollment No.

140610119001 140610119002140610119003140610119004140610119005

OutlineSafetyElectricshock & its effectsSafety rulesGroundingCircuit protection devices

SafetyElectrical safety is very important in every

work in environment . The purpose of safety is to ensure the

safety of persons exposed to the risk of injury arising from electrical hazards.

Electrical Shock And Its EffectsAN ELECTRIC SHOCK IS THE PASSAGE OF

AN ELECTRIC CURRENT THROUGH THE BODY .

EFFECTS OF ELECTRIC SHOCK ON THE HUMAN BODY A PERSON MAY SUFFER INTERNAL HEMORRHAGS AND

DISTRUCTION OF TISSUES,NERVOUS AND MUSCLES.

Safety Rules1. Make it a habit to turn off electric

appliances when they are in not use.2. Must use protective devices such as

MCB,ELCB or FUSE.3. Never allow wire or lead to run under carpet

where they remained invisible.4. Touch your appliances with dry hands only.5. Take away your children from electric

earthig.

6. Never ever overload sockets .

First AID BOX For Electric Shock First aid is the first action taken in an

emergency. Call for help. Turn off all power if this can be done

quickly. Check for breathing & heartbeats and apply

cardiopulmonary resuscitation, if necessary.

GROUNDING / EARTHING Earthing is connection to earth to provide

absolute zero potential. Earthing is given to the body of equipment so

as to divert fault current to ground through neutral wire.

WHAT IS EARTHING ? The process of connecting metallic bodies of all

the electrical appartus and equipments to huge mass of earth by wire having negliglible is called Earthing.

Importance Of The Earthing1. To protect the personnel from danger of

shock.2. Protection of equipments.3. Protection of large buildings and all

machines feed from overload. TYPES OF GROUNDINGS 4. Plate earthing5. Pipe earthing

Plate EarthingIn plate earthing, earth wire is connected to

copper or galvanized iron (G.I.) plate. PLATE DIMENSIONS COMMONLY

USED: For copper plate:60cm* 60cm* 3.18mm For G.I. plate: 60cm* 60cm* 6.35mm The G.I. plates are commonly used now-a-

days.

First, the selected plate is placed vertically inside the ground at a depth of 1.5m and is embedded in alternate layers of coal and salt to a thickness of 15cm.

The earth wire is drawn trough GI pipe and is perfectly bolted to the earth plate.

The GI pipe is fitted with a funnel on the top of the ground ; from that pipe, water is poured to maintain palate area at wet condition to keep low resistance.

A cement masonry chamber is built with a cast iron cover for easy regular maintenance.

Pipe Earthing

In pipe earthing, earth wire is drawn through 12.7 mm G.I. pipe.

First the pipe is placed upright at a depth of 1.75m in a permenently wet ground and the area surrounding the GI pipe is filled with an alternate layers of charcoal and salt to increase the effective area of the earth and to reduce the earth resistance respectively.

A cement masonry chamber is built with a cast iron cover for easy regular maintenance.

Circuit Protection Devices Protection for electrical installation must be

provided in the event of faults such as short circuit, overload and earth faults.

1. FUSES2. MCB3. ELCB4. RELAYS

Fuse

Fuse

1. A fault in an appliance can cause the current to be too great and can lead to the wire overheating and possibly causing a fire.

2. A fuse is designed to melt if the current through a circuit is too high, thereby breaking the circuit

3. The fuse should be just higher than the normal working current

4. A circuit breaker can be reset rather than replaced

Fuses & Circ

Fuses & Circuit Breakers

1.A fault in an appliance can cause the current to be too great and can lead to the wire overheating and possibly causing a fire.

2.A fuse is designed to melt if the current through a circuit is too high, thereby breaking the circuit

3.The fuse should be just higher than the normal working current

4.A circuit breaker can be reset rather than replaced

Miniature Circuit Breakers (MCB)Multi 9

The technologyActive parts

C60N NC100 / NC125

terminalfixed contactmovingcontactstrip braidmagnetictrip

load side terminal

terminalbimetral stripstrip braid

movingcontactmagnetic tripload side terminal

strip braidbimetal strip

4

Definition Protect cables against

overloads and short circuits

Let the current flow without overheating on cables

Open and close a circuit under rated current

Protect against insulation

faults (see earth leakage

protection module)

Main functions

Miniature circuit = switch + trip unit breaker (MCB) 4

Symbol

ELCB..

➲ Earth leakage protection is the process of detecting when the return current to earth is over a safe value & automatically breaking the continuity of the circuit to ensure the safety of an electrical installation.

➲ An electrical installation is a building or place that provides electricity for use by electricity consumers.

➲ A consumer of electricity is a person who uses electricity. The person is supplied either by an electricity supplier, or the person may provide his own electricity for his own use.

➲ An electricity supplier is any local authority, statutory body or person who supplies, contracts / agrees to supply electricity.

The End