EIT IDC Electrical Power System Fundamentals

1www.eit.edu.au

Electrical Power System

Fundamentals for Non-Electrical

Engineersby

Steve Mackay

www.eit.edu.au

EIT Micro-Course Series

Every two weeks we present a 35 to 45 minute interactive course

Practical, useful with Q & A throughout

PID loop Tuning / Arc Flash Protection, Functional Safety, Troubleshooting conveyors presented so far

Upcoming: Electrical Troubleshooting and

much much more.. Go to

http://www.eit.edu.au/free-courses

You get the recording and slides

The Engineering Institute of Technology (EIT) and IDC Technologies

Electrical Power System Fundamentals for Non-Electrical Engineers

2www.eit.edu.au

Overall PresentationThe focus of this session is the building

blocks of electrical engineering, the fundamentals of electrical design and integrating electrical engineering know-how into the other disciplines within an organisation.

www.eit.edu.au

Objectives The basics Design rules Selection,

installation and commissioning of electrical systems



3www.eit.edu.au

Topics

1. Generation, Transmission & Distribution

2. Transformers3. Earthing/grounding4. Power Quality5. Protection

www.eit.edu.au

1.0Electrical Power Generation, Transmission &

Distribution



4www.eit.edu.au

Energy Conversion Process of transforming one form of energy

into another In physics and engineering, energy

transformation is often referred to as energy conversion

Energy of fossil fuels, solar radiation, or nuclear fuels can be converted into other energy forms

Such as electrical, propulsive, or heating that are more useful to us.

www.eit.edu.au

Electrical Energy Electrical energy is undoubtedly the primary

source of energy consumption in any modern household.

Most electrical energy is supplied by commercial power plants.

The most common sources of power plants are:

Fuel energy Hydro-potential energy Nuclear energy



5www.eit.edu.au

Turbine

Rotary engine that extracts energy from a fluid flow

Has a number of blades, like a windmill Blades rotate when a liquid or gas (steam) is

forced through it under pressure. The rotating turbine is connected to a

generatorwhich produces alternating current electricity

www.eit.edu.au

Electrical Generator Device that converts kinetic energy to

electrical energy, using electromagnetic induction.

Reverse conversion of electrical energy into mechanical energy is done by a motor

The source of mechanical energy may be A turbine steam engine, Water falling through a turbine or

waterwheel, An internal combustion engine, Or any other source of mechanical energy.



6www.eit.edu.au

Electrical Generator (contd) The generators are the key to getting

electricity These are very large containing magnets

and wires Power lines are connected to the generator

to carry electricity.

www.loc.gov www.terragalleria.com

www.eit.edu.au

Electrical Generator (contd) A metal shaft connected to a

turbine is being turned by falling water or steam.

As the turbine rotates, the shaft coupled to the generator also rotates

Therefore the generator components also rotate and produces electricity.



7www.eit.edu.au

Coal-Fired Power Plant

www.tva.gov

www.eit.edu.au

Combustion Turbine Power Plant

www.tva.gov



8www.eit.edu.au

Hydroelectric Power Plant Hydro-electric power plants convert the

kinetic energy contained in falling water into electricity.

There are two types: Hydroelectric dam Pump-storage plant

www.eit.edu.au

Nuclear Power Plant (contd)

www.snapshot-net.eu



9www.eit.edu.au

Modern Power Station Overview

www.eit.edu.au

Alternative Energy Sources Renewable energy sources are the

alternative sources to generate electricity Solar energy Geothermal energy Biomass energy Ocean energy Wind energy



10

www.eit.edu.au

Transmission of Electric Power

Generated electricity at power plant is sent out over a power grid through transmission lines.

Transmission Transporting high-voltage electricity using a giant network of cables (the National Grid)

Power transmission is between power station and substation.

Transmission is carried out by bare overhead conductors strung between tall steel towers.

www.eit.edu.au

Transmission (contd) When electricity leaves the power station, it

is transformed upwards to 400,000 volts (400kV)

Transmission takes place at very high voltages to minimise losses.

Super Grid is a giant network of overhead lines and underground cables

It transports the electricity to substations and then distributed.



11

www.eit.edu.au

Transmission Losses Lightning strokes cause huge current flow,

therefore produces I2R losses. Tree limbs falling across the power lines

cause short circuits. Due to the interference of the

communication cables losses occur. Accumulation of ice on the conductors in

cold countries cause damage to the conductors.

Environmental conditions also effect the transmission efficiency.

www.eit.edu.au

Distribution of Power

Taking electricity to homes, industries and schools in towns and cities in different areas.

Then supplied to homes at 230V,50Hz or 110V, 60Hz by local distribution

Power is transformed down from the ultra high transmission voltages to lower voltages by series of substations

When higher voltages (132kV) are used, this area of supply is called 'Sub-Transmission.



12

www.eit.edu.au

Distribution (contd) Typical distribution voltages vary from

34,500/19,920 volts to 4,160/2400 volts. The end point of this supply is a "Zone"

Sub-station Here the electricity is transformed down to

11kV or 22kV for distribution to the immediate vicinity of customers.

Power is carried through overhead wires or through underground cables.

www.eit.edu.au

Distribution (contd)

For supply to residential consumers -- the voltage has to be transformed down again to 415/240 volts

This occurs at local sub-stations which are located close to customers.

Padmount Transformers are transformerswhich supply small voltages at this local sub-station.

From here power is carried directly to the customer's premises



13

www.eit.edu.au


www.eit.edu.au


www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation.html#Distribution



14

www.eit.edu.au

AC Power AC power flow has the three components:

Real power (P) It is in phase with the applied voltage

(V)Also known as the active component.Measured in watts (W)

Reactive power (Q)It is not in phase with the applied

voltage (V)Also known as Idle or wattless powerMeasured in reactive volt-amperes (VAr)

www.eit.edu.au

Power Factor It is the ratio of the real power to the

apparent power.

An ideal power factor is unity or 1.



15

www.eit.edu.au

Fig.1 Fig.2

Fig.3

Power Factor (Contd)

www.eit.edu.au

2.0 Transformers



16

www.eit.edu.au

Transformers A transformer efficiently raises or

lowers AC voltages It cannot increase power so that if the

voltage is raised, the current is proportionally lowered and vice versa

For an Ideal Transformer The voltage ratio is equal to the turns

ratio Power In is equal to Power Out

www.eit.edu.au

Transformers

Internal losses reduce the power OutVsVp

NsNp

=

Pp = Vp Ip = Vs Is = Ps



17

www.eit.edu.au

Large power transformers

www.eit.edu.au

Distribution Boards Serve as the point at which electricity

is distributed within a building. Usually consists of breakers or fuses .



18

www.eit.edu.au

3.0Earthing/Grounding

www.eit.edu.au

Need for Earthing The primary goal of earthing system is

SAFETY. Secondary goals are effective lightning

protection, diminishing electromagnetic coupling (EMC), and the protection against electromagnetic pulses (EMP).



19

www.eit.edu.au

Earthing reduce the risks of fires and personnel injuries.

To provide a low impedance route for high frequency leakage currents.

Need for Earthing

www.eit.edu.au

Electric shock (Direct and indirect)

An electric shock occurs when electric current passes through human body

Two categories of electric shocks are: Direct contact shock Indirect contact shock



20

www.eit.edu.au

Direct contact shock A direct contact shock occurs when conductors

that are meant to be live such as bare wire or terminals are touched.

www.eit.edu.au

Indirect contact shock Indirect contact shock is touching an exposed

conductive part that has become live under fault conditions.



21

www.eit.edu.au

Effects of electrical shockThe effects depend upon the following: The amount of current The path of the current The length of time the body remains in

contact with the circuit The frequency of the current

www.eit.edu.au

Muscular contractions freeze the body when the amount of current flowing

through the body reaches a level at which person cannot let go

increases length of exposure current flow causes blisters, reduces

surface resistance to current flow, increases current flow, causes severe injury or death

Effects of electrical shock



22

www.eit.edu.au

Extensor muscles fling the body Jerk reaction results in falls, cuts, bruises,

bone fractures, and even death

Effects of electrical shock

www.eit.edu.au

Touch and Step voltage



23

www.eit.edu.au

Protection From the Hazards of Ground-Potential

Gradients

www.eit.edu.au

The use of insulated equipment can protect employees handling grounded equipment, and conductors.

Restricting employees from areas where hazardous step or touch potentials could arise can protect employees not directly involved in the operation being performed

Protection From the Hazards of Ground-Potential

Gradients



24

www.eit.edu.au

Earth conductors and Electrodes

There are two main types of earth conductor, "bonding" conductors and earth electrodes.

Bonding and Protective Conductors are two types:Circuit Protective Conductor (CPC)Bonding Conductors

www.eit.edu.au

Bonding Conductors These ensure that exposed conductive parts

remain at the same potential during electrical fault conditions.

The two forms of bonding conductor are:- Main equipotential bonding

conductors Supplementary bonding conductors




25

www.eit.edu.au

Bonding Conductors The conductor size is capable of dealing

with anticipated fault current. If a fault develops, the whole of the fault

current may flow through via the earth conductor through to the "in ground" electrode system.

Once there, it will normally be split up between the various electrodes.


www.eit.edu.au

Earth Electrodes Direct contact with the ground provides a

means of releasing or collecting any earth leakage currents.

Earthed systems requires to carry quite a large fault current for a short period of time and,

It has a cross-sectional area large enough to carry fault current safely.




26

www.eit.edu.au

Electrodes must have adequate mechanical and electrical properties.

To meet demand for long period of time. During which actual testing or inspection is

difficult. The material should have good electrical

conductivity and should not corrode in a wide range of soil conditions.


www.eit.edu.au

Materials used include copper, galvanized steel, stainless steel and cast iron.

Copper is generally the preferred material

Aluminium is sometimes used for ground bonding.

The corrosive product - an oxide layer -is non-conductive.

Corrosive product reduce the effectiveness of the earthing.




27

www.eit.edu.au

4.0 Power Quality

www.eit.edu.au

Power Quality

It is defined with respect to three primary components

Continuity Quality Efficiency



28

www.eit.edu.au

Causes of Power Quality Problems

Voltage fluctuations (flicker) Voltage dips and interruptions Voltage Imbalance (unbalance) Power frequency variations Harmonics

www.eit.edu.au

Voltage Variations Short duration (sag, swell) Long duration

Undervoltage Overvoltage

Voltage Imbalance Voltage Fluctuations.



29

www.eit.edu.au

Voltage Sags (dips):

Causes:

Decrease between 0.1 and 0.9 p.u. in rms voltage or current at the power frequency for duration from 0.5 cycles to 1 min.

Local and remote faults.

Short Duration Voltage Variations

www.eit.edu.au

(contd)Impacts: Dropouts of sensitive customer equipment

such as Computer crashes Bulbs glow dim Fan speed reduces Effect on motor speed Poor video quality of televisions etc.



30

www.eit.edu.au

Voltage Swells (surges):

Causes:

Increase to between 1.1 and 1.8 p.u in the rms voltage or current at the power frequency for durations from 0.5 cycle to 1 min.

Single-line-to-ground faults.

Equipment over voltage.

www.eit.edu.au

(contd)

Impacts: Electronic equipments such as

television, computers will mis-operate Small fuses in electronic equipment

will blow off Bulbs of low power rating will blow off Failure of MOVs forced into

conduction etc.



31

www.eit.edu.au

Overvoltage:

Causes:

Increase in the rms ac voltage greater than 110 percent at the power frequency for a duration longer than 1 min.

Load switching off Capacitor switching on System voltage regulation.

Long Duration Voltage variations

www.eit.edu.au

(contd) Impacts:

Electronic devices will burn Refrigerator will blow off Winding of motors of fan mixers and

grinders will burn Over heating of equipment Bulbs will blow off Fuses will blow off Causes short circuits which will result

sparks in the circuit etc.



32

www.eit.edu.au

Under Voltage (Brown out)

Causes:

Decrease in the rms ac voltage to less than 90 percent at the power frequency for a duration longer than 1 min.

Load switching on Capacitor switching off System voltage regulation.

www.eit.edu.au

(contd)

Impacts: Video on the TV will not appear but one

can still hear the audio Mixers and grinders may not start Computer crashes Filament bulbs will glow dim but

fluorescent bulbs may not glow. Mis-operation of refrigerators etc.



33

www.eit.edu.au

Variation of frequency

The deviation of the power system fundamental frequency from its specified nominal value (e.g. 50 or 60 Hz).

www.ackadia.com/computer/images/ups_power_sag.gif

www.eit.edu.au

Causes: Poor speed regulations of local

generation Faults on the bulk power system Large block of load being disconnected Disconnecting a large source of

generation.

(contd)



34

www.eit.edu.au

(contd)

Impacts: Equipment Failure Black outs Transformers will blow off Motor windings will burn due to over

heating. Motors in mixers, grinders, fans will

burn.

www.eit.edu.au

Interruptions

Momentary Interruption: 1/2 - 3secs

Temporary Interruption: 3 - 60 secs

Long-Term interruption (outage): >1 min



35

www.eit.edu.au

(contd) Causes:

Temporary faults. Lightning stroke. Tree limbs falling across conductors.

Impacts: Operation interruption. Production losses. Revenue losses.

www.eit.edu.au

Surge

An unexpected increase in voltage i.e. a increase of 110% of normal voltage for more than three nanoseconds is considered a surge.

www.ackadia.com/computer/images/ups_power_sag.gif



36

www.eit.edu.au

Surge Protector A device that shields electronic devices from

surges in electrical power, or transient voltage, that flow from the power supply.

www.eit.edu.au

Switching Surges A transient disturbance caused due to

switching on/off of reactive load. Load switching Oscillatory switching Capacitor switching Multiple re-strike switching Power system switching Arcing faults Fault clearing Power system recovery.



37

www.eit.edu.au

Lightning Surges A high voltage transient in an electric circuit

due to lightning.

www.leonardo-energy.org

www.eit.edu.au

Lightning surges in electrical systems can in general be classified according

to their origin as follows: Direct flashes to overhead lines Induced over voltages on overhead lines Over voltages caused by coupling from

other systems.

(contd)



38

www.eit.edu.au

Effects of Surges Electronic devices may operate erratically.

Equipment could lock up or produced garbled results.

Electronic devices may operate at decreased efficiencies.

Integrated circuits may fail immediately or fail prematurely. Most of the time, the failure is attributed to "age of the equipment".

www.eit.edu.au

(contd)

Motors will run at high temperatures resulting in motor vibration, noise, excessive heat, winding insulation is lost.

Degrade the contacting surfaces of switches, disconnects, and circuit breakers.

Electrical and electronic appliances will blow



39

www.eit.edu.au

Lightning Arrestors A device that protects from lightning surges.

Lightning arrestors

www.eit.edu.au

5.0 Protection of Electrical Systems



40

www.eit.edu.au

Incipient faults A fault that takes a long time to

develop into a breakdown of insulation caused by: Partial discharge currents Normally become solid faults in

time.

Breakdown of Insulation

www.eit.edu.au

Solid fault Immediate, complete breakdown of insulation causing: High fault currents / energy Danger to personnel High stressing of all network

equipment due to heating and electromechanical forces and possibility of combustion

Dips on the network voltage affecting other parties

Faults spreading to other phases



41

www.eit.edu.au

Need for protection Protection is also needed to avoid

Electric shocks Electrical burns Arc blast injuries Fire

www.eit.edu.au

THANK YOU FOR ATTENDINGIf you are interested in further training please visit;

IDC TechnologiesTwo-day practical workshops available to the public:

www.idc-online.com/course_schedule/On-site customised workshops:

www.idc-online.com/training/Technical Manuals:

www.idc-online.com/products/Conferences:

www.idc-online.com/cons/

The Engineering Institute of TechnologiesPractical online Certificate, Advanced Diploma and Graduate Certificate

programs:www.eit.edu.au



42

www.eit.edu.au

If you are interested in further training in the area


UKManchester 3 & 4 November

Birmingham 7 & 8 NovemberLondon 10 & 11 November

http://www.idc-online.com/training_courses/electrical_engineering/?code=EN&

South AfricaJohannesburg 8 & 9 September

www.idc-online.com/training_courses/electrical_engineering/?code=EN

CanadaToronto 28 & 29 November

Calgary 1 & 2 Decemberhttp://www.idc-

online.com/training_courses/electrical_engineering/?code=EN

New ZealandAuckland 5 & 6 December

www.idc-online.com/training_courses/electrical_engineering/?code=EN



Documents

EIT IDC Electrical Power System Fundamentals