Protective Devices In Electrical Equipment Engineering Essay
What is a safe workplace?
A safe workplace is one where exposure to hazards is avoided or minimized. In a safe workplace, an atmosphere of safety is created through a constant awareness of safety and by educating people to know how to avoid or minimize personal exposure. Elements of a safe workplace include the following:
An electrical safety program
Responsibility and accountability
Recognition of factors of influence
Safe workplace will give the positive results of maintaining safety in workplace which can be measured from no injuries to people and no loss of equipment or production. A few factors involve related to the need in maintaining a safe workplace which:
The right thing to do
1.2 SAFETY CATEGORY
Safety category can be divided into three categories which are personal, tools and equipments, as well as workplace safety, and its environment.
Accidents can happen due carelessness. Therefore, it is important to pay attention to personal safety. In order to prevent accidents from occurring, safety rules must be adhered. Table 1-1 shows some of the rules that are commonly practiced in workshops.
Table 1-1: The rules that are commonly practiced in workshops.
Wear attire that is suitable for the task to be undertaken.
Wear insulated, low-heeled shoes.
Do not wear any jewellery such as necklaces, bracelets, and rings.
Do not wear neckties.
Always adhere to instructions from the teachers or supervisors
Plan your activities before you begin your work.
Keep the workplace tidy
Report all malfunctions or breakdowns of equipment
Use the right tools for the job and make sure that you know how to use them properly
In case of accidents, inform the teacher or the supervisor immediately
Have good eyesight
Have good hearing
1.2.2 TOOLS AND EQUIPMENT
Most tools and appliances operate with electricity. Therefore, electrical tools and appliances must always be kept in good condition and should be equipped with safety features as regulated by the Energy Commission (EC). Three ways in ensuring safety for tools and equipment are insulation, earthing and protective device.
Figure 1-2: Electrical appliances with insulation
Insulation is a method of protecting, covering or isolating electrical conductors using insulator to prevent the electrical current from flowing. The material used as an insulator must be high of resistance type. The most common insulators used in electrical appliances are rubber, polyvinyl chloride, and bakelite.
Figure 1-3: Illustration on earthing
Earthing is a method of connecting metal parts in an electrical circuit to the ground. Earthing protects the user from dangers of electrical shock when electricity flows to any metal part or to the wiring of an appliance or equipment. A good earthing system can disconnect the circuit when there is a leak of current to the ground.
Figure 1-4: Fuse position in plug and sample of circuit breaker
A protective device is a device that reacts by disconnecting the circuit when there is an overflow of current. The fuse and circuit breaker are two protective mechanisms commonly used in appliances and equipments. The current rating of such mechanisms depends on the current that are required to operate the appliance.
1.2.3 WORKPLACE AND ENVIRONMENT
Workplace in this field mean of workshop which need to be a comfortable and safe place to work. Several rules must be adhered to and practiced by students, such as:
Making sure that all equipment and furniture are kept neatly and safety to prevent doorways from being blocked, especially the main doorways.
Making sure that the workshop has good aeration.
Making sure that the workshop has enough lighting.
Making sure that the surrounding is neat and clean.
Noise minimization to ensure that all instructions from the teacher or supervisor are heard clearly by all students.
Know the location of the fire extinguisher so it can be easily reached in the event of fire.
Understand all instructions that are displayed in the Emergency Plan.
Every student must know what to do in the event of fire. Fire drills must be conducted at least twice a year.
Identify the location of the first aid kit. Report to the teacher or supervisor if the content of the first aid kit is incomplete or damaged.
1.3 ELECTRICAL ACCIDENTS
Accidents at workplace might occur when the safety is neglected. Accidents are result from carelessness, equipment malfunction and not adhering to safety rules. Generally, there are four types of electrical accidents which are electric shock, burns, fire and explosion.
1.3.1 ELECTRIC SHOCK
Electric shock occurs as a result of an excessive amount of electrical current flowing into the body of victim. This may be caused by inadequate insulation, poor earthing or the usage of a damaged circuit breaker.
Figure 1-5: Poster of first aid for electric shock
There are three categories of electric shock based on the amount of current that flows into the victim's body. Table 1-2 shows the current rating and the effects of electric shock.
Table 1-2: The current rating and the effects of electric shock.
Mild electric shock
Severe electric shock that causes burns and loss of muscle control
100 mA and higher
Electric shock that could be fatal
Burns can happen on the outside or inside of a victim's body. Burns are classified into three degrees.
Table 1-3: Degrees of burns classification
Redness on the skin can be seen
Cause the skin to swell and contain liquid
Reach inside the body and can cause failure of muscular functions. Most damaging and need specialist treatment.
Fire is a tragedy that happens due to multiple reasons. An overflow of electrical current can cause fire. In Malaysia, fire are classified into five classes, namely Class A, B, C,D, and E. Table 1-4 shows the classification of fire and its detail.
Figure 1.6 Fire triangle
Table 1-4: The classification of fire and its detail
Fire which involves solid material which mostly organic-based solids (wood, paper, fabric and other organic material)
Fire that affect from liquid substances (petrol, oil, diesel, turpentine and other flammable liquids)
Fires that are causes by gasses (butane, acetylene, and other flammable gases) and electrical equipment (electrical wiring, fuse box, electrical device and others)
Metal-based fire (potassium, sodium, calcium and magnesium)
Fire from cooking oil that are used commercially
Fires caused by electrical failures are classified into various classes depending on where the wiring or the electrical installation was undertaken or the type of material used. Fires caused by electrical failures are caused by:
Non-functional insulated cables causing short circuit.
Faulty earthing system.
Failure of the protection mechanism to function such as the fuse value being too high, overloading etc.
Faulty lightning arrestor.
Fire can be controlled by using appropriate fire extinguishers. There are four different types of fire extinguishers that are commonly used: water, chemical bubbles, carbon dioxide gas, and dry powder. All these fire extinguishers are distinguished by their respective colour casings.
Below is a table 1-5 show the different types of fire extinguisher and their uses. The suitable fire classes are also listed on the cases.
Table 1-5: The different types of fire extinguisher and their uses
Carbon dioxide gas (CO2)
Extinguishing Class A fires
Extinguishing Class A and B fires
Extinguishing Class B, C and D fires
Extinguishing Class A, B, C fires
22.214.171.124 USING A FIRE EXTINGUISHER
Before using your fire extinguisher, be sure to read the instructions before it's too late. Although there are many different types of fire extinguishers, all of them operate in a similar manner. Use this acronym as a quick reference:
Pull the Pin at the top of the extinguisher. The pin releases a locking mechanism and will allow you to discharge the extinguisher.
Aim at the base of the fire, not the flames. This is important - in order to put out the fire, you must extinguish the fuel.
Squeeze the lever slowly. This will release the extinguishing agent in the extinguisher. If the handle is released, the discharge will stop.
Sweep from side to side. Using a sweeping motion, move the fire extinguisher back and forth until the fire is completely out. Operate the extinguisher from a safe distance, several feet away, and then move towards the fire once it starts to diminish. Be sure to read the instructions on your fire extinguisher - different fire extinguishers recommend operating them from different distances.
Remember: Aim at the base of the fire, not at the flames!!!!
Figure 1-7: Poster on how to operate an extinguisher
Explosion that happen as a result of electrical failures are mostly caused by short circuits between live and neutral cables. A powerful explosion can cause fire. A big and uncontrolled fire may result in loss of life and the destruction of property.
Figure 1-8: Explosion cause from arc flash
The word ergonomics comes for two Greek words, "ergon" and "nomos". "Ergon" means work and "nomos" means natural law or rule. So, Ergonomics is "Natural Law or Rule of Work".
The International Ergonomics Association (IEA) defined ergonomics (or human factors) as "the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and a profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance".
Figure 1-9: Example of ergonomics design for hand drill
Ergonomics can be classified into three main areas: Physical Ergonomics, Cognitive Ergonomics and Organizational Ergonomics.
Physical ergonomics concerned with human anatomy, anthropometry, physiology and biomechanics.
Cognitive ergonomics concerned with mental processes such as perception, memory, reasoning, and motor response.
Organizational ergonomics concerned with optimization of sociotechnical systems including their organizational structures, policies and processes.
Ergonomics is a multidisciplinary area. The major contributing disciplines in Ergonomics are Mathematics, Psychology, Chemistry, Biological Sciences, Engineering & Technology, Physics and Epidemiology.
1.4.1 ERGONOMICS RISK FACTORS
There are a few factors that may contribute to ergonomics risk:
Repetition - Performing same or similar movements frequently.
Repetition - Typing thousands of words a day
Awkward Postures - Deviation from "neutral" body position. Examples of awkward postures are reaching, bending, twisting.
Awkward Posture - A rubber tapper tapping too low
Forceful Exertion - Amount of physical effort required to perform a task.
Forceful Exertion - A worker lifting heavy load to transfer the load to the pallet
Static Postures - Holding one position for long period of time
Static Posture - A researcher using a microscope for a long period of time
Contact Stress - Part of body in contact with hard or sharp surface
Contact Stress - A computer user typing while the wrist in contact with sharp edge
Other risk factors include vibration and environmental factors such as Noise, Temperature, Humidity, Lighting and Ventilation
1.4.2 RISK OF INJURIESÂ
Risk of injuries increases with:
Duration of exposure
Frequency of exposure
Intensity of exposure
Combination of risk factors
1.5 FIRST AID
First aid is a method of giving immediate medical assistance to accidents victims. First aid helps to save lives, prevents the injuries from worsening and eases the pain of the victims.
If first aid is not given to accident victims instantly, especially those whose heart beat and breathing has stopped, there is a slim chance the victims surviving the accident. Those who give first aid should know the correct methods of doing this. Each individual should be ready to give first aid whenever required.
First aid involves giving immediate medical assistance to an accident victim.
Those who give first aid assistance (other than doctors and nurses) must be trained by recognized bodies such as the Malaysian Red Crescent Association and St. Johns Ambulance Association.
Figure 1-10: Example of content in the first aid box
1.5.1 TREATMENT OF ELECTRIC SHOCK VICTIMS
Generally, electric shock victims will lose consciousness, stops breathing and the heart will stop beating. In cases of severe electric shock, parts of the victim's body that come into contact with the electric will appear burnt. There is a chance of internal injuries.
Actions to be taken
If the electric current still flowing, ensure that the electric supply is switched off. Use an object with an insulator to push away the live conductive wire. The victim's heart beat will stop if a live wire carrying electric current stays in prolonged contact with the victim's body.
The victim must be moved away from the danger zone and if necessary, provide the appropriate resuscitation techniques to revive him.
1.5.2 TREATMENT OF ELECTRIC BURNS VICTIMS
126.96.36.199 Minor Burns
For minor burns, including first-degree burns and second-degree burns limited to an area no larger than 3 inches (7.6 centimeters) in diameter, take the following action:
Cool the burn. Hold the burned area under cool (not cold) running water for 10 or 15 minutes or until the pain subsides. If this is impractical, immerse the burn in cool water or cool it with cold compresses. Cooling the burn reduces swelling by conducting heat away from the skin. Don't put ice on the burn.
Cover the burn with a sterile gauze bandage. Don't use fluffy cotton, or other material that may get lint in the wound. Wrap the gauze loosely to avoid putting pressure on burned skin. Bandaging keeps air off the burn reduces pain and protects blistered skin.
Take an over-the-counter pain reliever. These include aspirin, ibuprofen (Advil, Motrin, others), naproxen (Aleve) or acetaminophen (Tylenol, others). Use caution when giving aspirin to children or teenagers. Though aspirin is approved for use in children older than age 2, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. Talk to your doctor if you have concerns.
188.8.131.52 Major Burns
For major burns, call 999 or emergency medical help. Until an emergency unit arrives, follow these steps:
Don't remove burned clothing. However, do make sure the victim is no longer in contact with smoldering materials or exposed to smoke or heat.
Don't immerse large severe burns in cold water. Doing so could cause a drop in body temperature (hypothermia) and deterioration of blood pressure and circulation (shock).
Check for signs of circulation (breathing, coughing or movement). If there is no breathing or other sign of circulation, begin CPR.
Elevate the burned body part or parts. Rise above heart level, when possible.
Cover the area of the burn. Use a cool, moist, sterile bandage; clean, moist cloth; or moist towels.
SUMMARY & USEFUL TIPS
In a safe workplace, an atmosphere of safety is created through a constant awareness of safety and by educating people to know how to avoid or minimize personal exposure.
Electrical tools and appliances must always be kept in good condition and should be equipped with safety features as regulated by the Energy Commission (EC). Three ways in ensuring safety for tools and equipment are insulation, earthing and protective device.
Accidents are result from carelessness, equipment malfunction and not adhering to safety rules. Generally, there are four types of electrical accidents which are electric shock, burns, fire and explosion.
There are four different types of fire extinguishers that are commonly used: water, chemical bubbles, carbon dioxide gas, and dry powder. All these fire extinguishers are distinguished by their respective colour casings.
If the electric current still flowing, ensure that the electric supply is switched off. Use an object with an insulator to push away the live conductive wire. The victim's heart beat will stop if a live wire carrying electric current stays in prolonged contact with the victim's body. The victim must be moved away from the danger zone and if necessary, provide the appropriate resuscitation techniques to revive him.
What are electrical accidents? State four results of these accidents.
State the elements of safe workplace.
What are the three safety features that are required for an electrical appliance?
Why must we follow safety rules in a workshop?
Accidents at workplace might occur when the safety is neglected. Accidents are result from carelessness, equipment malfunction and not adhering to safety rules.
Generally, there are four types of electrical accidents which are
Elements of a safe workplace include the following:
An electrical safety program
Responsibility and accountability
Recognition of factors of influence
The three safety features that are required for electrical appliances are
Safe workplace will give the positive results of maintaining a safe workplace which can be measured from no injuries to people and no loss of equipment or production
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