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Measuring Frequency in a generator
How do you go about measuring frequency in a stand alone generator without a guage?
simonmeridew
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Measuring Frequency in a generator
I'm not an electrician. But there is no way to measure with out an instrument.
If you have a old plug in clock you can time the second hand and get in the ball park. This is based on what I've read can not tell you for sure it works.
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Measuring Frequency in a generator
If you are asking how to obtain 60 hertz power output; the generator armature shaft must be turned at 3,600 rpm. Many small craft marine type generators as well as standby genrators are mated to engines which are governed at 3,600 rpm. Other manufacturers in order to reduce noise, vibration, and fuel consupmtion have gone to a 2:1 gearbox or pulley drive that spins the generator at 3,600 rpm. PTO generators are geared in a variety of drive ratio's but the bottom line is the generator must be spun at 3,600 rpm if you want 60 hertz power.
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Measuring Frequency in a generator
Why not just buy a cheap meter? Something like:
http://store.yahoo.com/tmt/trip2030c.html
Unless your question was just one of curiosity, then frequency is simply 1/time. Equivalently, a Hertz = (1 cycle)/(1 second). You need 60 cycles/second, so if you know that your generator is based on a certain RPM, then you could potentially do things like strobe the drive shaft with a reference frequency or use magnetic pickups. But that is too much work...opt for the meter.
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Measuring Frequency in a generator
There is only one relyable way to do it, you need an oscilloscope. They can be easily found at the electrical engineering department of the local Uni or community college. Many Faculty will demonstrate the use of the device to their students if you are prepared to take the unit down to their location. We were always messing aroung with them in our Elec. Eng. labs at good ole UK (University of Kentucky) - Go Wildcats!!
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Measuring Frequency in a generator
Huh? While it is true that you can view the signal on an oscilloscope, frequency measurement is far more accurate and safer with a ground-isolated (battery-operated portable) frequency counter. Connecting an oscilloscope to a generator or other A/C power source is dangerous since the case of the instrument is grounded to one of the leads. Hook it up wrong, and you'll risk electrocution and equipment damage.
But then, what do I know? I only have an MS in electrical engineering. 
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Measuring Frequency in a generator
Metastable, you have to be kidding, what kind of oscilloscope have you been using. We used a "run of the mill" HP oscilloscope which was insulated to at least 1200 volts. It made no difference which lead was connected to which terminal since neutral (ground) was considered to be floating. There would not be a living elec. eng. student living if that was the norm. Oscilloscope manufacturers would have been sued out of existence?
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Measuring Frequency in a generator
You can measure the frequency easily with a oscilloscope, but it is a bit of over kill. There are plenty of hand held meters available today. A meter or oscilloscope is only as good as it's timing chip. Some of the old oscilloscopes did not have that good of timing chips. Most are quartz today.
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Measuring Frequency in a generator
Thanks for all who are helping me.
So I can get a frequency meter at Radio Shack, and connect across the hot 115 lead and the neutral and read directly? I did have an old analog VOM meter years ago which had a frequency mode in one switch position, but that's long gone. Now I have a digital VOM setup, but it doesn't seem to have any frequency reading capability.
simonmeridew
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Measuring Frequency in a generator
Not every meter is capable of reading the frequency. Mine doesnot either. The better meters are inductive, they just clip over the electrical wire.
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Gas Generator Weather Protecti
10-31-2005, 19:48 
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