Re: Dynamo Voltage (possible) Hazard

Posted by: Anonymous

Re: Dynamo Voltage (possible) Hazard - 05/21/20 07:33 AM

Originally Posted By: ConRAD
... yes that's true, but 30mArms are to be regarded as a sort of an "alert borderline" ... and NOT as a "trustable no-exitation safetyline"[/b]...
This IEC-diagram is only a little part of the electrical safety issue and cannot be taken out alone. The hugh amount of data for this issue is based on animal tests and on recalculation of fatal accidents and started around 100 years ago.
At first all these values are based on probability calculations, furthermore there are attentuation factors for the current path relativ to the standard left hand - left foot. The body resistance is between 500 and 1300ohm but the skin resistance can be around 10kohm - especially for low voltage applications. Therefore IEC defines "extra low voltage" below 50V (ACrms) and below 120V (DC). This is regarded as safe and non-lethal for permanent touch by normal adults.
A bicycle dynamo cannot exceed around 3 - 5W if operated with resistive load (intended use) due to the (high) internal inductance. This can be easily calculted with a AC-circuit ("komplexe Wechselstromrechnung"). Forumslader is not an intended use of a bicycle dynamo because it compensates this internal inductance by an external non-resistive load (a capacitor). But still the voltage limit 50V (ACrms) is normally kept and there is no safety issue. If you plug this dynamo with two needles around the heart area like a cardiac pacemaker then you will have an effect. I would not recommend to do this.