Would it be a good idea to include a Ground Fault Current Interruptor between the mains and the transformer inside a device itself? It seems like it would be a good method for shock prevention and much safer than just a fuse(abit more expensive but...).
AD
Fuses are for fire prevention, not shock prevention. ;-)
--Mac
For shock prevention the usual method is make sure that the live conductor can not come in contact with anything that a user can touch. This is usually done be meeting spacing requirement, insulation requirements and mechanical holding requirements. The requirement are specified in UL specs if you are in the US and IED specs if you are in the EU. A GFI will not releive you of these other requirements.
Dan
-- Dan Hollands 1120 S Creek Dr Webster NY 14580 585-872-2606 dan.hollands@gmail.com www.QuickScoreRace.com
"Abstract Dissonance"
** No !To be effective, a GFCI must be fitted to a *correctly wired* circuit - ie plugged into a regular wall outlet or installed in the fuse box by a sparkie.
If fitted inside an appliance, protection against the most common shock hazard ( live voltage appearing on earth ) is lost.
....... Phil
Why would it matter? Does it just look at the difference between the current going into the device and fault when it gets larger than a tolerance?
i.e.
-------+--- Mains A Device -------+---
A is a special device that adds the to currents together and if its absolute value is larger than some tolerance then it would trip the power to the device. It shouldn't matter what is hot and what is neutral(since it works only on the difference).
like lets suppose I know that the current drawn from my device is only 100mA
+- 10mA's (just a hypothetical) then I could create a GFCI that trips when the difference is more than 10mA's on the high side(so anything less than 110mA's is ok).Ofcourse this supposes that the current drawn from the device is relatively constant and the tolerance is small but for some devices this seems appropriate...
maybe a better method would be to work with the rate of change of the difference so that if it spikes then it would trip. So long as the current difference isn't changing extremely fast then it might be ok too?
it would also seem to me that one can easily make a device that can check for the right hookup so one doesn't have to worry if the wall outlet is hooked up properly(ofcourse I guess if you use a transformer then it doesn't matter though). i.e., one can check the volatage to the ground and find out which one is hot and use some relays to switch to the right configuration... i.e.,
------\\ /--------- \\/ /\\
------/ \\---------
------\\___/---------
___
------/ \\---------
where the two are simply the two possiblities that one has depending if the outlet is wired properly or not and is selected by some relays that depend on the voltage across from the ground and the mains(so it would require the the GND to be hooked up properly though).
AD
"Abstract Dissonance"
** The GFCI must have AC power applied to it in order to work - which is not the case when a wiring error in the AC lead connects *active* onto the metal parts of an appliance. ** No.The name says "ground fault ..."
Ergo, current flow *to ground* trips the device - as little as 20 mA.
........ Phil
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