Electricity Merit Badge

Electricity Merit Badge
Class 3 – Electric Power We Use Alternating Current (AC) Safety & Conservation Instructor-author Bruce MacAlister, IEEE Senior Member and W4BRU Office: Richmond, VA See instructor aids, next slide 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Electricity Merit Badge Class 3 - 2017 National Scout Jamboree
Classes Class 1 – Basics Electricity Class 2 – Magnetism Class 3 – Electric Power, Alternating Current Generating electricity Step up and step down voltages Safety devices Conservation Class 4 – Safety at Home Instructor demo items: Zero-center microamp meter for magnetic induction demo Coil with iron core of spikes for magnetic induction demo Large magnet on a string for magnetic induction demo 2 alligator clip test leads for magnetic induction demo Wall-wart, small plug-in step-down transformer with or without DC rectifier to show Pole-mount fuse (large) Analog kilowatt-hour meters (large) Set of bulbs, incandescent, CFC (florescent), LED Incandescent flashlight LED flashlight 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

The Electricity We Use – a Quiz
Where does the electricity come from to power these? Clockwise from upper left Desktop PC – plug in 120v “mains” Cell or mobile phone – rechargeable battery Incandescent flashlight – disposable batteries Chocolate chip cookies – a trick to see if they're paying attention Nintendo WII – plug in 120v “mains” TV set – plug in 120v “mains” Laptop PC – both plug in 120v “mains” and rechargeable battery Nintendo DS - disposable batteries Part of requirement 4. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

DC – Mostly Batteries DC means “Direct Current” It doesn't change much Hook a battery to a meter or a bulb See, it doesn't change much Refers back to Class 2 Part of requirement 4. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

AC – What Comes Out of The Wall
AC means “Alternating Current” It's what comes out of the wall outlets It “alternates” from high to zero to low to zero to high... and on and on It alternates very fast + Direction Sine wave from Circular drawn on slide Explain that we can't see flow, so we draw it to understand it There are special machines called oscilloscopes that let us see it Sine wave looks at it over time Circular is how it “looks” to a motor or light bulb Part of requirement 4. - Direction 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Generating AC Spin magnet near coil See energy go from zero to high to zero to low Spin speed is the “frequency” At home it's 60 cycles per second Demonstrate with coil, magnet, and meter that shows plus and minus Slow spinning of the magnet give the widest swings of the needle, up to 20 microamps. Faster spins illustrates increasing frequency. If Internet connection available, search for “video alternating current” and “electric generator video education”, “homemade electric generator” Potential sites as of April 2009: 7 minutes 5 min, a little dull 3 min build it demo 7 min, how to build, entertaining See “AC Generation Demonstrations for Scout Electricity Merit Badge Counselors.pdf” for construction and alternatives using digital mulitmeter Part of requirement 4. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Power Plants Generate Electricity
Electric company power plants work the same way Spin magnets in front of three coils Uses steam turbine or wind or water to spin Coils “make” electricity that’s sent to your home Part of requirement 4. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

How to Spin a Generator Steam Turbine Spins because steam pressure presses against turbine blades Spinning turbine spins a generator Used more than any other form of generation Top, turbine blades being repaired Example: Small fan to blow into with small motor as generator Bottom, turbine in its large silver-colored enclosure Round yellow enclosure on the right is the generator spun by the turbine Part of requirement 4. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Steam from ... Coal The machines are so big it's difficult to show a picture of each Diagrams show how they work Top is coal, left to right coal comes in from railroad cars, is crushed, put in furnace and burns, heats water to high pressure steam, steam spins turbine, turbine spins generator, electricity leaves on wires at the right Left, nuclear reaction in uranium rods gets very hot, heats water to high pressure steam, steam spins turbine as with coal Bottom is “dual cycle” gas turbine Gas at bottom burns, spins turbine like jet engine, turbine spins generator same as coal and nuclear Left over hot gases from gas turbine heats water into low pressure steam, steam spins a second turbine just like coal and nuclear Part of requirement 4. Nuclear Natural Gas 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Very Old & Very New Forms of Generation
Hydroelectric, falling water Wind where it is windy Solar where there is much sun Dams hold water, it falls against turbine blades and spins generators; oldest form of electric generation Wind spins blades like a fan and it spins a generator; new for electricity but old windmills used to pump water Strong sunlight falls on photo-voltaic cells, pushes electrons and starts a wave of energy through the wires attached to them; very new Part of requirement 4, 6, 9b. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Getting the Power to the Consumers
Power generation plant to… High Voltage transmission lines to… Substation to … Distribution lines to … A house or business 125,000 to 750,000 volts 25,000 volts 7,500 to 35,000 volts Voltages: (1) about 25kvolts out of generator (2) raised to 125k to 750kvolts to make transmission more efficient to (3) neighborhood substation where it's dropped to 7.5k to 35kvolts and sent overheard or underground to house where (4) a transformer drops it to 120 and 240volts for the home. Part of requirement 4. 120 & 240 volts 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Why Change Voltages? Power company sends 120,000 watts to a shopping center At 120 volts that’s: 1,000 amps BIG wires BIG pole to hold the BIG wires At 125,000 volts that’s: 1 amp small wires little pole to hold the little wires Explain why voltages change on prior slide; to reduce the amount of current that must be transported long distances. Big wires = big pole Also: High current means lots of energy lost to heat. Heat is a waste, so this conserves electricity for everyone Part of requirement 4, 9b 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Remember Power Formula?
P (watts) = I (amps) x E (volts) so I (amps) = P (watts) / E (volts) I = 120,000 watts / 120 volts so I = 1,000 amps Remind students of formula; probe for questions or confusion on doing formula Memory Jog: “Easy as PIE” in that P = I x E Part of requirement 4, 9b I = 120,000 watts / 125,000 volts so I = .96 amps 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

But Not High Voltages Everywhere
Very high voltages near people are dangerous Voltages are reduced closer to people and buildings That’s what you see here 125,000 to 750,000 volts 25,000 volts 7,500 to 35,000 volts Reiterate what voltages are used where Part of requirement 4 120 & 240 volts 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Voltage Changed by a Transformer
Primary coil (windings) is input Secondary coil (windings) is output Step-up or Step-down Ratio of windings determines up or down voltage Remind students of the electromagnet, how electricity through the coil made a magnet If two separate coils are put near each other and alternating current is sent through one, it will act like a moving magnet The “moving magnet” coil will put electricity into the coil near it Iron core or “square donut” helps the magnetic forces work more efficiently. Top diagram is how to Bottom picture is a plug-in transformer; 120 volts AC down to 16 volts AC Hold up a Wall-Wart as an example they see lots of Part of requirement 4 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Transforming Power With AC, transformers change the voltage up and down Step up transformers increase the voltage (electrical pressure) so power companies can use smaller wires to carry the current (energy) Wires on the poles or underground near your house carry 7,000 to 35,000 volts Step down transformers reduce it to 240 volts (for your stove and A/C) and 120 volts (for your lights, TV, etc.) Remind students of the electromagnet, how electricity through the coil made a magnet If two separate coils are put near each other and alternating current is sent through one, it will act like a moving magnet The “moving magnet” coil will put electricity into the coil near it Part of requirement 4. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Where Transformers are Found
Dialog What runs in the high voltage part? (7 to 35kv) Point out that the wires on the poles could run underground instead What runs in the low voltage part? (240 and 120v) Part of requirement 4. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

What Transformers Look Like
Have students tell which transformers are for what and relate to prior slide Upper left: step up transformers at power station (typically 20-some kv to 250 to 1,000 kv) Upper right: step down transformer for overhead electric lines (typically 7 to 35kv dropping to 240 and 120v) Bottom: step down transformer on the ground for underground electric lines ((typically 15 to 35kv down to 240 and 120v) Ask students what they've seen near their houses Part of requirement 4. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

What Happens When Power Lines Go Bad
Source with videos When they touch each other or touch the ground or touch a piece of equipment on the ground they short out with these results and things burn Using too much power for a line and the line can burn setting buildings and fields on fire. Part of requirement 1. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Preventing Power Accidents
Too much current (amps) on the line trips: Big circuit breakers in substations Fuses on poles Fuses in transformer cabinets That turns off power in the lines Make the point that just like your home, power companies use circuit breakers and fuses Part of requirement 1. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

How You Can Prevent Power Accidents
Why are these dangerous? Left; ladder is close to power lines, so if it falls backwards, it hits the line. This picture is from a news article and that’s what happened! Center; even digging to plant flowers can be dangerous. You need to know where the underground wires are. You can call a free service to have the underground lines marked. Right; same problem as center. People get killed this way! Part of Requirement 2. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

What Happens When You Touch a Power Line
Yuck! This slide is designed to shock. If your ladder touches a power line, you can burn like these pictures If a metal pole touches the power line you can get burned If your hand or any part of your body touches the power line you can get burned What is really scary is it will burn your insides, your guts, as it passes through you. That can make you sick for years! Sometimes it kills the person holding the ladder or touching the wire From Part of requirement 1. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Keep Safe Around Power lines Above You and Under You
Scouts should be alert to power lines above them Kites, ladders, antennas, wires, ropes can all come in contact with 7,000 to 35,000 volts That kills people! Scouts should know there are power lines buried in the ground below them Digging holes, putting in fence posts, driving stakes can touch a power line if you don’t know where they are. Part of Requirement 2. Don’t let anything get near the electric wires Call 811 before you dig to have underground wires marked 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Marked Underground Power Line
This man called 811 for marking Red stripes mark the underground line Dig at least 2 feet away from marked line Underground marking crew finds the lines Dashes of red paint mark the location of the underground electric conductors Part of Requirement 2. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Conservation – Saving Energy
Measuring the Electricity Used Read meter from left to right Notice some numbers go clock-wise, some go counter clock-wise Read two months, subtract to find kilowatt hours used If meters are available, pass them around Part of Requirement 9. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Calculating Consumption
If last month was 14840 And this month is 15964 Then – = 1124 kilowatts-hours used At $0.10 per kilowatt = $112.40 Reduce the kilowatt-hours used and you reduce the cost Probe for confusion by students Part of Requirement 9. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Reducing the Power You Use
How much power do these use? How is a lumen different from a watt? Lumens measure the light output; watts measure the power consumed. Incandescent on left, 850 lumens, 60 watts, 0.5 amp CF (compact fluorescent) in middle, 800 lumens, 13 watts, 0.1 amp LED on right, 600 lumens, 10 watts, 0.08 amp CF bulbs are usually cheaper to own. They're more expensive to buy but use very little electricity and run for years before they burn out LED are new, much more expensive and don't save much more than CF bulbs but may last 10 to 20 years! With more engineering, they're expected to be less expensive to own than CF bulbs. Part of requirement 9. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Finding Lower Powered Stuff
More power consumed means more coal burned, more natural gas burned, more nuclear fuel used EnergyStar label on an appliance means it uses less power than others Check the label for power usage Part of requirement 9. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Give 5 Ways Your Family Can Conserve Energy
From Electricity Merit Badge booklet 35886,ISBN , page 51 Turn off lights and electronic equipment after use Clean or replace heating and air-conditioning filters at least once a month Install low-voltage outside lights Do full loads of laundry. Grill food outside. Requirement 9B 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

Reducing Power on the Small
LED flashlights save batteries Fewer batteries means less in land- fills LEDs work especially well with small batteries because they use so little power. Thus the flashlight is smaller. LED flashlights don’t focus as well as incandescents, so they’re not very good searchlights. (LEDs don’t have a small point-source to be focal point, but they probably will soon.) Optional: run ammeter test comparing the two flashlights to show lower current flow from LED flashlight Part of requirement 9. 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

What We Learned AC means alternating current AC is what we use in our homes for lights, etc. Spinning magnets near coils of wire is how power companies make most of the electricity Transformers step up and step down voltage for efficiency Electricity can burn and cause fires if not handled properly Circuit breakers and fuses prevent fire 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

What We Learned Stay away from power lines above and below you New bulbs can save electricity Lumens measure amount of light Watts measure the power consumed EnergyStar means less power consumed LED means Light Emitting Diode LED flashlights use less power so batteries last longer 8 May 2018 Electricity Merit Badge Class National Scout Jamboree

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