Another Question From Me

[Dairyspark]

Hi everyone, in my never ending quest to find knowledge I have a question for you smart lot

What are Triple harmonics?

Cheers

Bobby

 

[Sidewinder]

It's not triple, it's triplen.

Have a look see and let us know what you think it is about, and more to the point, why are mentioned.

i.e. why you asked in the first place...

 

[steptoe]

my toes are still sore

:coat

 

[Phoenix]

In a simplified way.

If you imagine a simple resistive load such as a heating coil, the current waveform follows the voltage waveform of the supply, ergo if you have three the same, one on each phase, they balance and you have no neutral current.

3ph motors are also balanced loads, however they current waveform lags behind the voltage waveform.

Now if you look at electronic loads containing a switch mode PSU, the input stage generally consists of a bridge rectifier feeding into a capacitor bank. The behavior is of these are that they draw high currents when the voltage of the supply exceeds the voltage in the caps. The result is that have a none sinusidual current wave form, consisting of a sharp peak co-inciding with the peaks of the voltage waveform. Because these are so narrow they do not cancel but rather add together and the neutral current could be a lot higher than you expect it to be based on RMS readings of the phases. As there are three phases all putting these peaks onto the neutral, you start to get frequencies of 150hz introduced.

 

[kerching]

3,9,15,21 etc

I like 5 and 11 myself

i prefer all prime numbers!

watched a prog this afternoon on ''''unraveling the worlds first computer'....it was a brass cog wheel affair discovered by some divers off Greece.

amazing, all based on 2000 year old cog wheels configured around prime numbers

absolutely fascinating

 

[Dairyspark]

I was just wondering lol and as far as I read it's something to do with 3 phase circuits and the neutral and something to do with traveling currents down the neutral

 

[kerching]

I was just wondering lol and as far as I read it's something to do with 3 phase circuits and the neutral and something to do with traveling currents down the neutral

in a similar way to the disgraced Liberal MP Cyril Smith

you have mail

 

[binky]

Bit of education for me! If you have a balanced 3 phase output from say a 3 phase inverter, is the neutral current basically bugger all?

 

[NozSpark]

Not on the single phase side

 

[binky]

or the dc side :slap

My software always comes up with cable sizes that suggest neutral is basically unloaded, but i've always wondered how true this is. All inverters (solar) have a small overnight load and claim 0.95 max out of balance,(excuse lack o tecnical terms cos it's late and brain is addled by wine) but i've always wondered how true this is. I need to do some reading when I have time

 

[SLIPSHOD & SLAPDASH]

So its nothing do do with this lot then

https://www.youtube.com/watch?v=51N4F6FyI40

:coat