understanding electrical engineering and safety for non-electricians

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Technology Training that Works www.idc-online.com/slideshare Understanding Electrical Engineering and Safety for Non- electricians

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Electrical engineering is often considered to be a mysterious science, because electricity cannot be seen. However, we are all aware of its existence and usefulness in our daily lives. This workshop aims to take the mystery out of electrical engineering and give a good understanding of the fundamental principles of electricity. While many of us work on electrical systems, we do not fully appreciate the dangers, which we get exposed to when doing so. All it takes is a few simple precautions to avoid getting hurt. This workshop teaches you all about the dangers of careless handling of electrical appliances and prevention of electrical accidents. This workshop is not meant for electrical engineers and other qualified technicians. It is for those who are not formally trained as electricians but often have to handle and maintain electrical appliances in the course of their work. The participants will have an opportunity to understand how the appliances they see everyday actually function. This workshop will deal with the subject with a minimum of theory while emphasising on the practical, hands-on approach. WHO SHOULD ATTEND? Civil, mechanical, chemical, mining engineers, technologists and technicians Managers who are involved with or work with staff and projects in electrical engineering Non-electrical engineers and technicians Non-electrical personnel who want to understand the broader picture Plant and facility engineers Procurement and buying staff Project managers Sales engineers MORE INFORMATION: http://www.idc-online.com/content/understanding-electrical-engineering-and-safety-non-electricians-24

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Page 1: Understanding Electrical Engineering and Safety for Non-Electricians

Technology Training that Workswww.idc-online.com/slideshare

Understanding Electrical

Engineering and Safety for Non-

electricians

Page 2: Understanding Electrical Engineering and Safety for Non-Electricians

Technology Training that Workswww.idc-online.com/slideshare

What is Electric current? An electric current is a movement or flow of charge

similarly like the flow of water moving through the tube (wire).

Flow of charges in a wire

Page 3: Understanding Electrical Engineering and Safety for Non-Electricians

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Charge / Quantity

Charge is of two types

• Positive charge

• Negative charge

Charge is carried by tiny particles called Electrons.

Coulomb = litre current = litre/second

Page 4: Understanding Electrical Engineering and Safety for Non-Electricians

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What is Electricity? Flow of current that is used to power lights, motors, tools,

and many other devices.

Page 5: Understanding Electrical Engineering and Safety for Non-Electricians

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How are charges moved? An amount of energy is needed to

move.

POTENTIAL DIFFERENCE or VOLTAGE is that energy or electric force which causes charges to move.

10 Volts sends more current than 1 Volt.

Page 6: Understanding Electrical Engineering and Safety for Non-Electricians

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PRESSURE Water pressure results from the head of water, e.g. a dam

and is regulated to the customer Electricity comes from a power station, regulated along

the way Different pressures and capacities necessitate different

sized pipes at different sections of the route Differing voltages and current carrying requirements

require varying size conductors and cable insulation

Page 7: Understanding Electrical Engineering and Safety for Non-Electricians

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Electric Cell There should be an energy source to provide this energy

or voltage.

ELECTRIC CELL is one such source.

Page 8: Understanding Electrical Engineering and Safety for Non-Electricians

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A Simple Circuit A battery connected by conductors (copper wire) to

electrical components (bulb).

Page 9: Understanding Electrical Engineering and Safety for Non-Electricians

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Charges moving in a circuit

Voltage from energy source causes current

Page 10: Understanding Electrical Engineering and Safety for Non-Electricians

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Electrical current is defined as

electrons flowing between two points having a difference in voltage potential.

Current is measured in amperes or amps (A).

Litres per Second - Ampere Water cycle via evaporation and rain Closed loop of electron flow. Either via “Earth” or dedicated conductor

Electric Current

Page 11: Understanding Electrical Engineering and Safety for Non-Electricians

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Resistance

Resistance is a property that slows the flow of electrons––the current.

Resistance causes an opposition to the flow of electricity in a circuit. It is measured in OHMS ().

Page 12: Understanding Electrical Engineering and Safety for Non-Electricians

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Resistance Resistance to flow increases with decreasing size

of pipe/conductor Resistance creates losses/Heat Losses proportional to square of current Doubling voltage halves current, reduces losses to

one quarter.

Page 13: Understanding Electrical Engineering and Safety for Non-Electricians

Technology Training that Workswww.idc-online.com/slideshare

Pressure Drop Loss incurred overcoming resistance reduces

pressure Same effect water and electricity Equipment requires a minimum pressure to work

efficiently Pressure/voltage drop must be controlled

Page 14: Understanding Electrical Engineering and Safety for Non-Electricians

Technology Training that Workswww.idc-online.com/slideshare

Ohm’s Law Ohm's Law is a mathematical equation explaining the

relationship of voltage (V), current (I), and resistance (R)

It is defined as:

Page 15: Understanding Electrical Engineering and Safety for Non-Electricians

Technology Training that Workswww.idc-online.com/slideshare

We notice static electricity when the air is very dry.

When the air is more humid, the water in the air helps electrons move off you more quickly, so you can not build up as big a charge.

Static Electricity

Page 16: Understanding Electrical Engineering and Safety for Non-Electricians

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Direct current (DC) and Alternating current (AC)

Flow of current can be DIRECT Current (DC) or ALTERNATING Current (AC)

Page 17: Understanding Electrical Engineering and Safety for Non-Electricians

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Direct current is a continuous current (I) per unit time

Alternating current is current (I) that reverses multiple times per second

In AC-- currents are sinusoidal function of time.

DC and AC Currents

Page 18: Understanding Electrical Engineering and Safety for Non-Electricians

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V

TIME0

1

0.5

Direct Current (DC)

Page 19: Understanding Electrical Engineering and Safety for Non-Electricians

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Cycle (degree)

V

0 90 180 270 360-1

-0.5

0.5

1

0

Alternating Current (AC)

Page 20: Understanding Electrical Engineering and Safety for Non-Electricians

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Electric Energy or Electric Work Energy is defined as ‘the ability to do work’ --as measured

by the capability of doing work (potential energy) or the conversion of this capability to motion (kinetic energy).

Electrical energy is usually measured in watt-hours.

Electric work is said to be done when an electric charge flows through a conductor.

The SI unit of electrical energy is the joule.

Page 21: Understanding Electrical Engineering and Safety for Non-Electricians

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Electric power Defined as the amount of work

done by an electric current per unit time.

The unit of power is WATT

For a resistor in a D C Circuit the power is given by the product of applied voltage and the electric current

Power = Voltage x Current

Page 22: Understanding Electrical Engineering and Safety for Non-Electricians

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Relationship Power is the rate at which electrical energy is

transmitted

Power is energy per unit time

=Electrical power

Electric work (or energy)

Time in seconds

Page 23: Understanding Electrical Engineering and Safety for Non-Electricians

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Single phase AC

A single-phase system is one where there is only one AC voltage source (one source voltage waveform).

Page 24: Understanding Electrical Engineering and Safety for Non-Electricians

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Frequency Measurement of the number of occurrences of a

repeated event per unit of time (for example, 1Hz means an even repeats once per second. 2 Hz is twice per second, and so on.)

Measure the time between two consecutive occurrences of the event (the Time period T)

Page 25: Understanding Electrical Engineering and Safety for Non-Electricians

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Frequency Compute frequency as

f=1/T

SI Units is measured in hertz (Hz) named after the German physicist Heinrich Hertz.

Frequency was originally called cycle per second (cps), which is still sometimes used. Other units used to measure frequency include revolutions per minute (rpm).

Page 26: Understanding Electrical Engineering and Safety for Non-Electricians

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The generation of AC electric power is commonly three phase.

In Three phase AC, the waveforms of three supply conductors are offset from one another by 120°.

Standard frequency is 60 Hz.

Three Phase AC

Page 27: Understanding Electrical Engineering and Safety for Non-Electricians

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Three Phase Waveform

V12 V23 V31

Page 28: Understanding Electrical Engineering and Safety for Non-Electricians

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Advantages of Three Phase 3 phase power is typically 150% more efficient than

single phase in the same power range. 

The power delivered to the load is the same at any instant.  

Also, in 3 phase the conductors need only be 75% the size of conductors for single phase for the same power output.

Takes more load than Single Phase.

In a single phase unit the power falls to zero three times during each cycle, in 3 phase it never drops to zero.

Page 29: Understanding Electrical Engineering and Safety for Non-Electricians

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Phase Sequence Phase rotation, or phase sequence, is the order in which

the voltage waveforms of a Three phase AC source reach their respective peaks.

For a three-phase system, there are only two possible phase sequences: 1-2-3 and 3-2-1, corresponding to the two possible directions of alternator rotation.

Page 30: Understanding Electrical Engineering and Safety for Non-Electricians

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1-2-3 rotation: 1-2-3-1-2-3-1-2-3-1-2-3-1-2-3 . . .

3-2-1 rotation: 3-2-1-3-2-1-3-2-1-3-2-1-3-2-1 . . .

Phase Sequence

Page 31: Understanding Electrical Engineering and Safety for Non-Electricians

Technology Training that Workswww.idc-online.com/slideshare

DO YOU WANT TO KNOW MORE?

If you are interested in further training or information, please visit:

http://idc-online.com/slideshare