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Is it "Touch Safe" at Output Ground Terminal of Non-Isolated 415Vac-to-5Vdc ?

Posted by: Ravi Prasad P on

I am working in 3Phase-3Wire environment.
I have only option to use phase-to-phase voltage.
My extreme Mains Input conditions are:
Vmin(ph-ph) : 150Vac
Vmax(ph-ph): 459Vac
Vnom(ph-ph): 415Vac

My Output requirement is 5V@250mA.

I am planning non-isolated power supply similar to the one referred in RDR-737 suitably modified for 5V output.
Even I can choose Fail-safe configuration alternately.
I have only Ground Pin exposed outside my module.

In either of the cases, would it give Electric shock if my exposed ground is touched by humans?

Comments

Submitted by PI-Yoda on 07/23/2020

Dear Ravi,
From safety prospective, in any case exposing externally part of the primary mains other than Earth is unacceptable. It is because your GND is connected to mains Neutral, (I refer to DER737 as you mention).
Mains input voltages, output voltages and current, and Fail-safe configuration option are completely irrelevant in this case.
The "fail-safe" concept in a SMPS is an approach to prevent danger from a none-save condition appearing as a result of a single component failure.
If you expose the Neutral line outside your power supply the danger is already there, and "fail-safe" cannot do anything to prevent it.
Please, you MUST refer to the safety standards in your country, or IEC60950!
Best Regards,

Submitted by Ravi Prasad P on 07/23/2020

Thank you Yoda!