Hopefully someone can help.
I have a pure sine wave inverter and it runs everything I throw at it fine.
However I have a few questions. I live in Australia, 240vac @ 50hz, and I
have a small multimeter that has a HZ measuring function. when I put the
test probe in the power outlet at home, it shows a rock steady 50 hz. When
I put it in the inverter, is show something like 60 khz.
When I have an AC/DC adapter (for a laptop) attached to the power point, and
I put the Hz probe on the 12 volt output it shows 50 hz?? (Even though this
is the DC end of the adapter)
But when I use the AC/DC adapter on the inverter, the DC output also shows
I would love someone with technical knowledge to explain this to me... when
I test the inverter on an oscilloscope, it shows a nice clean 50 hz sine
wave, even though the multimeter show 60 khz.
I emailed the manufacturer of the inverter and this is his reply...
THE SINE WAVE PRODUCED IN THESE TYPES OF INVERTERS IS PRODUCED USING HIGH
FREQUENCY PULSE WIDTH MODULATION (PWM) TECHNIQUE. IT IS NOT 100 % SINEWAVE
BUT HAS APPROX. 3% THD. I AM NOT SURE HOW YOUR FREQUENCY METER WORKS. IT IS
LIKELY THAT IT IS READING THE HIGH FREQUENCY PWM CONTENT. THE 50 HZ
WAVEFORM MAY BE SEEN USING AN OSCILLOSCOPE.
Now I have two more questions, even though everything seems to work well on
the inverter, is there anyway that it is producing sub standard AC, and is
there any way the 60khz coming through the dc end of the adapter could
One final question, does anyone know a brand of pure sine wave inverter
that will definately produce AC power completely identical to a normal power
point outlet? (IE something that would show up as 50 hz when tested with my
Thanks in advance for any advice.
18 years ago