Re: [PSES] IEC60950-1 Limited Power Source via IC current limiter

Thu, 08 Mar 2018 14:34:50 -0800

I regard North American household GFCIs and industrial shunt trip GFCIs to not be fail safe because they can fail silently and therefore require period testing to verify continued functionality.  I believe that the UL standard for GFCIs has recently been updated to require some periodic self testing to address this issue.
Mike Sherman
Graco Inc.

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------ Original Message ------

From: John Woodgate
To: EMC-PSTC@LISTSERV.IEEE.ORG
Sent: March 8, 2018 at 3:57 PM
Subject: Re: [PSES] IEC60950-1 Limited Power Source via IC current limiter

Probably some fail-safe, some reliable. I think that this is why 'safety' involves risk-assessment, not just meeting standards.

John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2018-03-08 21:41, Richard Nute wrote:

 

In my early days in product safety, safety was prohibited from relying on conduction in a vacuum, gas, or semiconductor. 

 

Today… we rely on semiconductor current limiters and similar devices, e.g., GFCI control circuits. 

 

Are such limiters and control circuits fail-safe devices?  

 

Or, are they “reliable” devices and circuits where their lifetime is expected (proven) to be greater than the host equipment?

 

Rich

 

 

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