Hi,
Ah, I hadn't looked at the data sheet, and it does make a few "strange" statements*, but the formula should tell us what we need. The number of pulses per revolution is not important as such, although it's useful to tell us if the other figures look "sensible".
Personally, I worked backwards from a typical windspeed of 5 m/s (or around 11mph, 18 km/hr in units I'm more familiar with). For 5 m/s the formula says that the frequency F (which is the same as pulses per second) will be 4.9 / 0.0875 = 56 Hz, which is unusually high for an anemometer. So it clearly is generating quite a lot of pulses per revolution. If we assume 16 pulses/revolution then the rotational speed at 5 m/s would be 56 / 16 = 3.5 revs/sec.
I can't actually see the diameter/circumference (for the centre of the cups) in the diagram of #10, but 413mm could be "about right" (I estimated slightly less from the figures shown). So 3.5 revs/sec would give 1.445 metres wind run per second and an Anemometer Factor of (5.0 / 1.445) = 3.46. That's slightly higher than the values suggested by Wikipedia (the Fine Offset anemometer is also towards the higher end) and this particular anemometer doe have quite short "arms", so I think these figures are all "believable".
Therefore 16 pulses/rev may well be correct, but of course a more usual number of 1 or 2 could be used by changing the scaling or calibration factors as appropriate.
*A few of the parameters may have "lost something in translation" (from Chinese?). For example "Mechanical life: more than 20 million times" may look impressive, but I make that only ~4 days of 56 Hz pulses (5m/s windspeed) or ~66 days if "times" is interpreted as "revolutions". And "Electrical life: more than 70,000 times" must mean something very different.
Cheers, Alan.
Ah, I hadn't looked at the data sheet, and it does make a few "strange" statements*, but the formula should tell us what we need. The number of pulses per revolution is not important as such, although it's useful to tell us if the other figures look "sensible".
Personally, I worked backwards from a typical windspeed of 5 m/s (or around 11mph, 18 km/hr in units I'm more familiar with). For 5 m/s the formula says that the frequency F (which is the same as pulses per second) will be 4.9 / 0.0875 = 56 Hz, which is unusually high for an anemometer. So it clearly is generating quite a lot of pulses per revolution. If we assume 16 pulses/revolution then the rotational speed at 5 m/s would be 56 / 16 = 3.5 revs/sec.
I can't actually see the diameter/circumference (for the centre of the cups) in the diagram of #10, but 413mm could be "about right" (I estimated slightly less from the figures shown). So 3.5 revs/sec would give 1.445 metres wind run per second and an Anemometer Factor of (5.0 / 1.445) = 3.46. That's slightly higher than the values suggested by Wikipedia (the Fine Offset anemometer is also towards the higher end) and this particular anemometer doe have quite short "arms", so I think these figures are all "believable".
Therefore 16 pulses/rev may well be correct, but of course a more usual number of 1 or 2 could be used by changing the scaling or calibration factors as appropriate.
*A few of the parameters may have "lost something in translation" (from Chinese?). For example "Mechanical life: more than 20 million times" may look impressive, but I make that only ~4 days of 56 Hz pulses (5m/s windspeed) or ~66 days if "times" is interpreted as "revolutions". And "Electrical life: more than 70,000 times" must mean something very different.
Cheers, Alan.