[SystemSafety] Comment on Risks note on "Smart Power Outlets" (RISKS 29.72)

ECHARTE MELLADO JAVIER javier.echarte at altran.com
Fri Aug 26 10:00:58 CEST 2016

There is a safety normative for domestic household appliances (IEC 60730), including 3 categories of equipment's (A, B, C) like cooking, boiler and heater control, vacuum cleaners, washing machines...
This normative defines a set of internal testing for uC. Main chip manufactures provides SW libraries to implement these tests.
This normative is a very good complement for the 61508. It  surprises  me that domestic appliance manufactures are applying, in theory,  this normative (internal CPU testing, watch dog....) and some "SIL2 61508" or even "SIL4" developers... are very reluctant to include some of these internal tests and safety criteria...
Maybe the main internal test is the timer (clock test). If you programme a 10 minutes microwave oven and the oven is working for 100 minutes, you will have a problem...So, you need to implement and external  reference (quartz crystal) and compare it with the MCU internal oscillator. More cost and development time...

Javier Echarte

-----Mensaje original-----
De: systemsafety [mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de] En nombre de Peter Bernard Ladkin
Enviado el: jueves, 25 de agosto de 2016 17:40
Para: systemsafety at lists.techfak.uni-bielefeld.de
Asunto: Re: [SystemSafety] Comment on Risks note on "Smart Power Outlets" (RISKS 29.72)

On 2016-08-25 17:05 , Martyn Thomas wrote:
> It's not impossible (though culpably stupid) that someone would leave 
> a radiant heater plugged in somewhere that could cause a fire if it 
> was left on for a while. The electrical protection might cut in when the fire finally caused the cable to melt, but it would be too late ...

10 people died of this in 2011/12, apparently. Section 3 of http://www.electricalsafetyfirst.org.uk/news-and-campaigns/policies-and-research/statistics/
25 died in fires through faults, and 11 fires through misuse. I have no idea how these categories were determined.

Of course, it could only happen in countries which use electrical radiant spot heaters. I've not seen one in Germany. I once told my heating engineer's wife that I was using a Dyson blower for spot heating and she lectured me. Then her husband lectured me. Then his senior techie lectured me. I was worried the friendly neighborhood policeman was going to drop by..........


Prof. Peter Bernard Ladkin, Bielefeld, Germany MoreInCommon Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de

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