If you have an inverter at home, then you must have noticed that a fan runs faster when mains fails, and slows down when mains supply returns, but why?
2006-08-15 06:46:02 · 8 answers · asked by logikal 2 in Science & Mathematics ➔ Engineering
Short answer: Best guess is that your mains are 50 Hz but your inverter is 60 Hz.
If you are referring to the "mains", then you are likely in the UK. Where electrical service is 50 Hertz.
Invertors can come for 50 Hz or 60 Hz (as is used in North America). All that I have seen are 60 Hz (I'm in the USA).
Most everything works on either (if the voltage is right! - 120 versus 220 volts), but motors spin 20% faster on 60 Hz.
A few things have problems at a different frequency - especially clocks that derive their timing from the mains and old vinyl record players. Also some water and air pumps have more a limited range of allowable flow rates at 50 Hz.
You could get fancy and put an oscilliscope on the inverter output. But you've essentially already done that with the fan - its speed is proportional to the frequency of its power source.
2006-08-15 07:45:26 · answer #1 · answered by David in Kenai 6 · 1⤊ 0⤋
Never noticed a speed change. My inverter is a modified square wave type so fans and motors in general make a bit more noise. But since most all common fans use induction type motors the speed is directly related to the frequency of the power you feed them.
Are you sure your inverter is running at the same frequency as the grid in your area. If you are someplace on the planet where the grid is 50 Hz and you have a 60 Hz inverter you will notice a speed change, but I would think you would be having a lot of other problems.
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Andre' B.
2006-08-15 06:55:58 · answer #2 · answered by Andre' B 2 · 1⤊ 0⤋
Real motor speed is based partly on %slip. If the inverter is slightly higher in voltage then there may be a lower percentage of slip. Houses in Australia often have 235V after distribution lossses (Ideally should be 240V) some inverters are 250V (to cater for length of run losses as well). This might explain it and at least it is easy to check with a voltmeter. Failing that I would be looking at frequency; as others have said.
2006-08-15 19:14:16 · answer #3 · answered by slatibartfast 3 · 0⤊ 0⤋
The speed of a fan depends on the frequency and to some extent on the voltage of the electricity on which the fan is run.
The frequency and voltage of the inverter output are controlled by its circuit elements and it would appear that these are higher than those of the mains supply and may account for the higher speed of the fan when run on an inverter.
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2016-09-29 07:24:37 · answer #5 · answered by laseter 4 · 0⤊ 0⤋
The mains have stable freq. 60 cycles
But the inverters comes in all flavors. I don't know which one you used. It may be outputting a square wave. Then the freq effects the RPM. If you use true-sine wave inverters then it shouldn't vary at all. They are more expensive.
2006-08-15 06:56:57 · answer #6 · answered by Dr M 5 · 0⤊ 0⤋
probably because you're on the verge of a brown out to a black out
2006-08-15 06:55:18 · answer #7 · answered by shclapitz 3 · 0⤊ 1⤋
.where do you live where you get wierd shlt like this
2006-08-15 06:51:24 · answer #8 · answered by Anonymous · 0⤊ 2⤋