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About cleggsan
Expertise
All technical areas of Electronics Engineering.

Experience
BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.

Organizations
IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.
 
   

You are here:  Experts > Computing/Technology > Job Searching: Technical > Electrical Engineering > DC generator output at variable RPM

Topic: Electrical Engineering



Expert: cleggsan
Date: 12/16/2006
Subject: DC generator output at variable RPM

Question
I have a self-made wind turbine (daughter's project) with a 12VDC 10amp motor/generator attached to a resisitve load of 3V - 300mA.  Have taken alot of readings to calculate mean power output at given speeds. For example, at 6 m/s mean v=3 and mean amp=3.5.  Is the power it is producing simply p=v*i and how does changing the load effect determining the power output?

Answer
Resistive load would be in ohms.  Is the load a 10 ohm resistor?  (E = I*R, or R = E/I = 3v/.3a = 10 ohms)

If the load is a fixed resistor, then increasing the rotational speed will increase the voltage (and the power) output and decreasing the speed will decrease the voltage (and power).

Power output it calculated by P = E*E/R  or voltage squared divided by R.  At 3v out, for example, the power into a 10 ohm load would be 3*3/10 = .9 watts.  If speed increased to produce 4 volts out, then power out is 4*4/10 = 16/10 = 1.6 watts.  Conversely, if voltage drops to 2 volts, power out is 2*2/10 = 4/10 = .4 watts.

Does this help?  If I did not understand the scenario properly, please let me know.

Cleggsan


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