Safety Flashcards
What is electrostatic discharge?
Rapid transfer of electrons from one object to another. Static charge releasing electrons onto a neutral object
What is grounding?
Process of removing excess charge of a conductor by attaching it to an object of substantial size.
Describe the operational guidelines of a safe workplace
Always use test probes with safety guards
Always use insulated alligator clips
Never touch metal parts of the equipment you are working on
keep one hand behind your back when you’re taking a measurement
Coulomb’s law
Charge bodies attract or repel each other with a force that is directly proportional to the product of their charges and inversely proportional to the square of the distance between them
Factors of electrical shock
Body resistance
The path
Time
The effect of electrical shock at 1.1 milliamperes
Perception. A slight tingling sensation
The effect of electrical shock at 10 milliamperes
A 120 pound person cannot let go. Arm and hand muscles close involuntarily
The effect of electrical shock at 16 Milliamperes
A 175 pound person cannot let go. Arm and hand muscles close involuntarily
The effects of electrical shock at 18 milliamperes
Cannot breathe. Paralysis of the chest muscles
The affects of electrical shock at 65 milliamperes
Heart fibrillation. Rapid irregular contractions of the heart muscles. Can be fatal.
What is electrical shock
This in Seshan of muscular spasms caused by electrical current passing through the body
What does body resistance affect when it comes to electrical shock
The amount of current
What does the path of electrical shock affect
The entry and exit points on the body have a large influence on the severity of the shock
What does the amount of time affect when it comes to electrical shock
The severity
How to avoid shock
Isolate, insulate, ground.
Isolate
Isolate yourself from the source of electric shock, remove the power to the equipment before attempting to work on it, be sure to keep all electrical equipment, covers, doors, and enclosures in place we’re not working on the equipment. If youmust leave circuitry exposed, worn your fellow workers of the danger.
Insulate
Make sure that all the electrical tools and equipment used is properly insulated, use only approved insulated hand and portable electric power tools, check power and extension cords frequently for deterioration, cracks, or breaks. Breaks in the insulation can cause many electrical mishaps.
Ground
Electric current always follows the path of least resistance. To prevent yourself from being the unintentional path to ground, make sure that your equipment is well grounded. Well grounded equipment will direct any stray electric current to ground, thereby protecting you from electric shock. A good ground can also help protect the equipment from excessive voltage spikes or lightning.
What to do in case of electrical shock
Shut off the power at once.
If power cannot be shut off immediately try to free the victim from non-conductive material.
Do not make direct contact with any part of the victims body.
check if the victim is breathing.
Perform CPR if necessary.
Loosen the clothingfrom the victims neck chest and abdomen so that breathing is easier.
Protect the victim from exposure to cold. Keep the victim from moving.
After a strong shock, the heart is very weak.
Send for a doctor or a corpsman and stay with the victim. Do not give the victim stimulants.
What is one of the most serious problems facing the electronics industry today?
Electrostatic discharge (ESD)
Electrostatic voltages produced by walking across carpet
1500 to 35,000 V
Electrostatic voltage produced by walking on a vinyl floor
250 to 12,000 V
Electrostatic voltage is produced by a worker at a bench
100 to 6000 V
Electrostatic voltage is produced by common polybags
1200 to 20,000 V
What are the causes of electrostatic discharge ESD
Friction, separation, induction.
What does friction cause
A build up of static charge
How can separation cause electrostatic discharge
Figure it out. Search it on the net.
What is induction
When instead of charges developed in an object, and then object is brought close to another object which then becomes statically charged.
How do you control electrostatic discharge ESD
Assume, handle ESD sensitive items, store and transport.
What do you assume one controlling ESD
Assume that all components and assemblies are sensitive to ESD
How do you handle ESD sensitive items
Only handle is the sensitive items when you are properly grounded at a static-safe work area.
What are important factors in controlling ESD
Grounding, shielding, ionization.
What is shielding
Preventing exposure to an external electrostatic field, or charged objects.
What do you use to shield a static sensitive electronic component or Assembly
Metallized static-shielding bags.
What is an ionizer
floods an area with equal amounts of positively and negatively charged particles (ions). A charge material with and attract ions of the opposite polarity and quickly become neutralized
Ionization
Neutralizing nonconductors by means other than grounding since they do not conduct electricity
What is an ion
A charged Atom or molecule
What is a cation
A positively charged ion
What is an anion
A negatively charged ion
You will pick up at ESD precautions
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ESD
Electrostatic Discharge
