# Rectifier Ripple Factor Formula



## EEVA PE (Sep 25, 2011)

I have run across two different formula's for ripple factor, not sure which is correct.

Formula 1: which I think is correct:

r = (Vrms/Vavg) X 100

Formula 2: I stumbled across in the Complex Imaginary stuff exam #2 prob 35

r = (sqrt((Vrms/Vavg)-1)) X 100

What do others think is correct?


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## Jonjo (Sep 26, 2011)

EEVA said:


> I have run across two different formula's for ripple factor, not sure which is correct.
> Formula 1: which I think is correct:
> 
> r = (Vrms/Vavg) X 100
> ...



EEVA : r = (Vrms/Vavg) X 100 the Vrms is the value for AC components

and the

r = (√((Vrms/Vavg)²-1)) X 100 , missing the power of 2 and do not requiere the Vrms for the components .

Both are equavalent just wacth what number you put on it


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## Jonjo (Sep 26, 2011)

Jonjo said:


> EEVA said:
> 
> 
> > I have run across two different formula's for ripple factor, not sure which is correct.
> ...


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## xd-data-ii (Sep 27, 2011)

EEVA said:


> I have run across two different formula's for ripple factor, not sure which is correct.
> Formula 1: which I think is correct:
> 
> r = (Vrms/Vavg) X 100
> ...


That is not #35 in exam 2. It is a NEC overload protection question.

Which exam book do you mean?


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## EEVA PE (Sep 27, 2011)

xd-data-ii said:


> EEVA said:
> 
> 
> > I have run across two different formula's for ripple factor, not sure which is correct.
> ...




In mine it is, there must be multiple version releases. I got mine in June. Looks like poor Configuration Management, along with the errors.


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## EEVA PE (Sep 27, 2011)

I just threw my 4 Complex Imag exam books in the trash. They are causing me more harm than good.


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## Complex Imaginary (Sep 27, 2011)

I don't believe this problem contains an error. As explained above, there are two ripple factor formulas. The difference in the two formulas is which Vrms are you going to use: the rms value of the AC supply components; or the rms value of the outputted rectified waveform. In this particular problem, the waveforms are both given at the load, which means you have to use the formula of the latter.

As for the comment about poor configuration management, we performed a complete overhaul to all our tests in July to do our best to ensure as few errors as possible would be in the tests. This overhaul reconfigured the tests. We produce the books as they are ordered and alter the content to bring what's provided to the customer up to the latest, most accurate version. Errata has been sent to all previous customers. If you have not yet received it, please check your email (and spam filter) or email me at:

[email protected]

Thank you very much for the detailed analysis of this problem. Please understand that we are doing everything we possibly can to provide the most effective and accurate PE test prep. We can't be perfect, but we can be fair. Please contact me with your concerns and hopefully we can work something out.

Josh


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