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PHS Mark: / 30
AST406 Wind Powered Generator (WPG)Electrical Efficiency LabName: ____________
Problem:Determine the electrical efficiency of the WPG propeller system.
Materials: Power supply with voltmeter, ammeter, WPG, clock, toolbox, timer, balance, wire
1 Use the cables and set up the power supply so that it powers the WPG in a series circuit – NOT the light.
2 The voltage MAXIMUM is 4.0 Volts – any more will burn out the motor.
3 Starting at ZERO voltage, increase the voltage SLOWLY (4.0 V MAXIMUM) until the wheel turns one
complete rotation every 1-2 seconds – so you can count it. Keep the voltage at this level.
4 Determine and record the potential difference (voltage) at the power supply and the current intensity at
5 Determine how long it takes for the WPG propellers to make TEN (10) complete rotations – EXACTLY.
6 Repeat Step 5 twice more.
7 Measure and record the diameter of the WPG propeller blade system.
8 Carefully remove the WPG propeller, shaft and driver gear from the platform.
9 Determine and record the mass of the WPG propeller system, using the balance.
10 Separate out the different parts of the WPG. Wear safety glasses.
11 Clean up the lab site. Failure to do so will result in marks being deducted.
Voltage (V) Current (A) Diameter of
Propeller & Gear
Propeller & Gear
Time Trial 1 (s) Time Trial 2(s) Time Trial 3 (s) Average of 3 Trials (s)
Diagram of Circuit
Calculations: SHOW ALL WORK ---- Use a pencil – erase your mistakes – be neat. Include units. /18
1. Circumference (m) of WPG propeller blade system.
d – diameter (m)
2. Average time (s) for one complete rotation
= Average time for 10 rotations
3. Calculate the velocity (m/s) of the WPG propeller blades to make one complete rotation.
V = _d _(m/s)
d – distance – circumference (m)
t – time (seconds)
4. Kinetic Energy (Joules) is the energy of motion of an object.
Calculate the Kinetic Energy (KE) of the WPG propeller system.
KE = 1/2 m v 2
m – mass of fan (kg)
v – velocity (m/s)
5. Calculate the Electrical Energy (Joules) used during one rotation.
P = VI
E = Pt
6. Calculate the % Efficiency
= Kinetic Energy to turn WPG propeller system x 100%
Electrical Energy used
Conclusion: Answer the Problem. Did the WPG operate at 100% Efficiency? Why/Why not?
Sources of Error: