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PowerNex Associates Inc. Module #1 Basic Electricity www.pnxa.com

Module 1 Learning Objectives To gain an understanding of the following: • Basic Electricity (1A) • Units of Measurement • Energy and Power • Ohm’s Law and Joule’s Law • Electrical Losses, Parallel Paths • AC and DC • Frequency • The Transformer • Real and Reactive Power • Power Factor • Three Phase Power • Geography and History related to the Ontario power system (1B) • History and Growth of Ontario’s Power System • Functions performed by Ontario Hydro and where they now belong • The world outside Ontario, the interconnected system • NERC/NPCC

Module 1ABasic Electricity Units of measurement Voltage (volts) v (Kv) Current (amps) I or A Resistance (ohms) Frequency (hertz) Hz Power (watts) w (Mw) Reactive Power var (Mvar) Apparent Power va (Mva)

Basic Electricity Units of measurement Kilo (K) 1,000 Mega (M) 1,000,000 Giga (G) 1,000,000,000 Tera (T) 1,000,000,000,000 Typically Volts in Kv eg 230 Kv Watts in Mw eg 500 Mw Current as is eg 100 A

Basic Electricity Energy and Power

Basic Electricity • Energy is the ability or capacity to do work. • Energy and work are measured in the same units: eg joules. There are two main types of energy viz; • Potential energy (stored energy, eg gravity, coal, oil, gas, the atom). • Kinetic energy (motion energy, eg electrical energy, wind, sound) • Energy can be neither created nor destroyed (law of conservation of matter and energy), but it can be changed from one form into another • From potential energy to mechanical energy to electrical energy (as is the case with a hydro electric facility) • From heat energy in coalto mechanical energy to electrical energy (as is the case of a fossil fired facility)

Basic ElectricityEnergy and Power • The basic energy unit is the Btu. This stands for British thermal unit. A Btu is defined as the amount of heat energy it takes to raise the temperature of one pound of water by one degree Fahrenheit, at sea level. • One Btu roughly equals: • An average candy bar • One match • It takes, for example, about 2,000 Btus to make a pot of coffee. • 1,056 joules = 1 Btu • In most countries (except for the USA) energy is measured in joules rather than Btus.

Basic ElectricityEnergy and Power BTU Content of Common Energy Units • 1 gallon (imp) of gasoline = 149,000 Btu • 1 litre of gasoline = 33,000 Btu • 1 gallon (imp) of diesel fuel = 167,000 Btu • 1 litre of diesel fuel = 37,000 Btu • 1 barrel(42 US gallons/ 34 imp gallons) of crude oil = 5,800,000 Btu • 1 cubic foot of natural gas = 1,031 Btu

Basic ElectricityEnergy and Power • Power is a measure of how much work can be performed in a given amount of time or how rapidly a standard amount of work is done. • American cars for example are rated in "horsepower". In Europe many cars are rated in Kw. (1 horsepower = 0.746 Kw) • The power of a car's engine won't indicate how high a hill it can climb or how much weight it can tow, but it will indicate how fast it can climb a specific hill or tow a specific weight

Basic ElectricityEnergy and Power

Basic Electricity Ohm’s Law and Joule’s law

Voltage (V)equivalent to water pressure Current (I) equivalent to water flow Resistance (R) equivalent to restrictions in pipes Basic ElectricityOhm’s Law and Joule’s lawWater analogy for Voltage, Current and Resistance

Basic ElectricityOhm’s Law and Joule’s law • Electrical energy is governed by Ohm’s Law and Joule’s law • I = V/R (Ohm’s law) • where I is Current (amps), V is voltage (volts) and R is resistance (ohms). • P = V*I (Joule’s law) • where P is Power (watts) • Electrical energy is expressed in watt hours (power expended over a given amount of time)

Example Circuit must be complete for current to flow, if switch is open nothing happens. Current (I) = 12/3= 4 amps Power = 12 x 4 = 48 watts Energy over an hour = 48 watt hours Basic ElectricityOhm’s Law and Joule’s law

The lamp will light 1 second after throwing the switch! Basic ElectricityOhm’s Law and Joule’s law

Basic ElectricityOhm’s Law and Joule’s law • Now we can use these two formulae to show that : • P = V2/R • In other words power is proportional to the square of the voltage. • We can theoretically transfer four times the power if we double the voltage (important concept)

Basic Electricity Electrical Losses and Parallel Paths

Basic ElectricityElectrical Losses and Parallel Paths • Power losses occur when current flows though a resistance • P = V x I (Joule’s Law) • But V = I x R (Ohm’s Law) • Therefore P = I2 x R or I2R • These losses appear as heat – example is the electric kettle • In a transmission line the resistance of the line causes losses based on this formula, the higher the resistance and the current the greater the power losses.

R1 = 1 Ohm I = 9.09 amps R2 = 10 Ohms V = 100 Volts Basic Electricity Series Path • Total Resistance R = R1 + R2 = 11 ohms • Therefore I = V/R = 100/11 = 9.09 amps • Line Losses = I2 R1 = 82.6 x 1 = 82.6 watts Transmission Line Load (Customer)

RA = 1 Ohm RB = 1 ohm RC = 1 ohm I =9.7 amps R2 = 10 ohms V = 100 Volts Basic Electricity Parallel Path • I/R1 = 1/RA +1/RB + 1/RC = 1/1 +1/1 +1/1 = 3/1 • Therefore R1 = 1/3 ohm = 0.333 ohms • Therefore total Resistance = R1 + R2 = 10.333 ohms • Therefore I = V/R = 100/10.33 = 9.7 amps and line losses = I2 * R1 = 31 watts R1 Load (Customer) Lines

Basic Electricity Calculation: electrical voltage, current, resistance, and power

Basic Electricity Alternating Current and Direct Current

Basic ElectricityAlternating Current and Direct Current • DC stands for "Direct Current," meaning voltage or current that maintains constant polarity and direction over time. • AC stands for "Alternating Current," meaning voltage or current that changes polarity and direction over time.

Basic ElectricityAlternating Current and Direct Current

Basic Electricity Why Alternating Current (AC) is used and not Direct Current (DC) • The transformer's ability to step AC voltage up or down with ease gives AC an advantage unmatched by DC. • When transmitting electrical power over long distances, it is far more efficient to do so with stepped-up voltages and stepped-down currents, then step the voltage back down and the current back up for industry, business, or consumer use. • Cannot run induction motors with DC, most industrial motors are induction motors (simple and versatile). • DC is used to transmit power over very long distances but it is then converted back to AC for end use

Basic Electricity How AC Power is Produced Magnetism and Electricity are completely intertwined • Electric current (moving electric charge) creates magnetism (discovered by Andre-Marie Ampere in the 1820’s) • Moving magnets create current in nearby conductors (discovered by Michael Faraday also in the 1820’s)

If the magnet does not move there is no attraction If the material is not a conductor there is no attraction Basic ElectricityHow AC Power is ProducedMagnetism and Electricity are completely intertwined

When the magnet is moved a current is induced in the coiled wire. Basic ElectricityHow AC Power is Produced Magnet

Basic ElectricityHow AC Power is Produced

Magnetic lines of force are stronger (more numerous) at the two poles of the magnet When a rotating magnet passes a stationary conductor (wire) the induced current in the wire is greatest when each of the poles pass. This is why we get a sine wave N S Basic ElectricityHow AC Power is Produced

The rotor of an AC generator is a rotating magnet(s). The stator of an AC generator is a series of stationary windings and electric current is induced in them by the rotating magnet(s) Basic ElectricityHow AC Power is Produced

Basic ElectricityHow AC Power is Produced

A rotor and stator for a hydro-electric generator (note the number of poles) Basic ElectricityHow AC Power is Produced

Basic Electricity Frequency

Measured in cycles per second or Hertz. 60 Hertz in North America 50 Hertz in Europe Time for 1 cycle = 1/60 = 16.66 milli secs Basic ElectricityFrequency

Basic ElectricityFrequency At what rotational speed must an AC generator spin at to produce a frequency of 60 Hz? • RPM = frequency x 120 divided by number of pole pairs, where • RPM = revolutions per minute • f = frequency in hertz • Therefore the rotor of a machine with two pole pairs (typical fossil fired unit) rotates at 3600 RPM • Hydroelectric units rotate at much slower speeds, they have more pole pairs.

Basic ElectricityFrequency • Frequency is the basic metric used to ensure that there is sufficient generation to meet customer demand. • Lower frequency (< 60 Hz) means customer demand not being fully met • Higher frequency (> 60 Hz) means that customer demand is being oversupplied

Basic Electricity The Transformer

Basic ElectricityThe Transformer Np x Ip= Ns x Is Vp/Np = Vs/Ns

Basic ElectricityThe Transformer

Basic ElectricityReal and Reactive Power • The concepts of • Watts (real power) • Volt ampere reactive, Var (reactive power or imaginary power)

Basic ElectricityReal and Reactive Power • Reactive power is a concept used to describe the loss of power in a system arising from the production of electric and magnetic fields. • Although reactive loads such as inductors and capacitors dissipate no power, they drop voltage and draw current, which creates the impression that they actually do. • This “imaginary power” or “phantom power” is called reactive power. It is measured in a unit called Volt-Amps-Reactive (VAR). • The actual amount of power being used, or dissipated, is called true power, and is measured in the unit of watts. • The combination of reactive power and true power is called apparent power, and it is the product of a circuit's voltage and current. Apparent power is measured in the unit of Volt-Amps (VA).

Power in a purelyresistive AC circuit All the power is positive V = Basic ElectricityReal and Reactive Power

Power in a purely inductive AC circuit Note that the power is pulsating, no power is absorbed by the load. V = Basic ElectricityReal and Reactive Power

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