I need some help in designing an intrinsic safe power supply. the specification of the PSU is: Input voltage = 18Vdc; Output Voltage = 15Vdc; Output Current = 20mA dc. The intrinsic safe group is Group 1 and the category is "ia". Any help will be appreciated.

 

You might want to indicate the standards that you are following. While there may be some generic meaning to "intrinsically safe", you may be held to a very specific meaning or definition.

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stevez

 

The standard is IEC 0079-11 standard

 

Could you post a link or attachment giving the specification?

I would use a simple 78L15, cheap and compact.

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I've worked with several of these standards, specifically intrinsically safe, nonincendive and explosion proof.

Intrinsically Safe devices cannot cause enough spark energy to ignite a gas in a class I division II environment (division I would be explosion proof). Specifically, to be approved for CL I div 2 environments require approval from appropriate safety agencies here in the USA. It is not simply good enough to do an in-house design and say that "it is good", because (at least here in the USA), requires approval so that insurance companies will cover a loss. The minute they find out that an in-house design was used without agency testing and approval, all bets are off. So basically what I'm saying is that the design is not a big deal, its the approval process and being accepted by the insurance to be truly labeled as "intrinsically safe".

Hope that helps...

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