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Ripple on low voltage

Peterd
I look after a small fairground type railway. It is powered via a transformer and full wave rectifier and runs at around 35 volts. At recent inspections it has been noted that it fails as there is around 24 volt ripple on the 35 volt dc, which is not surprising as there is no smoothing. Apparently according to the person undertaking the inspection, who states it is to bs7671, the ripple should be no more than 10% ripple, however I cannot find any such requirement.

Has anyone got any experience of this type of thing, I am loathe to add a capacitor to smooth the dc - it would have to be probably around 0.1F, and ripple current in it could well be a problem.

Any thoughts on this would be appreciated, is there an actual requirement on ripple, or is it OK to just have full wave rectified dc as long as the peak voltage does not exceed the elv limits of 120v dc or 50 v ac rms .
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    I think that my first question would be what instruments were used to measure the dc and ripple?  The waveform would be non-sinusoidal so could not be measured with average reading rms indicating instruments.  The peak voltage could be estimated by measuring the ac input to the rectifier and calculating.


    By my calculation 35 Vdc from a full wave rectifier would have a peak voltage just under 55 V.


    David
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    I think that my first question would be what instruments were used to measure the dc and ripple?  The waveform would be non-sinusoidal so could not be measured with average reading rms indicating instruments.  The peak voltage could be estimated by measuring the ac input to the rectifier and calculating.


    By my calculation 35 Vdc from a full wave rectifier would have a peak voltage just under 55 V.


    David
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