[mythtv-users] HDPVR problems - power supply again?

Jan Ceuleers jan.ceuleers at gmail.com
Wed Aug 14 16:12:39 UTC 2019

On 14/08/2019 17:35, Will Dormann wrote:
> Given the over-current protection (OCP) features that my PSU itself
> advertises, plus the fact that that system is on a properly limited (via
> circuit breaker) circuit, I'm not terribly concerned about the HD-PVR
> bursting into flames.

I don't want to worry you, but I would not draw much comfort from either
of the protective layers you describe. The over-current protection in
your power supply may still allow your HDPVR to draw way more power than
it is supposed to, and the same is true of the circuit breaker.

The fire safety strategy of an electrical/electronic device is described
in its IEC 60950-1 test report. A device is permitted to consider itself
safe if it is certain that it will not be able to draw more energy from
its power supply than it can safely dissipate (i.e. if it is certain
that that power supply will shut down before it provides that amount of

So the designer of the HDPVR would count on knowledge about the design
of the bundled power supply about how much power it would (continue to)
supply under fault conditions, and for how long. An analysis of the
materials used in the HDPVR will then tell you whether that amount of
energy (power x time) could result in the materials catching fire.

Hooking a device to a more powerful power supply than the one that it
came with therefore negates some of the assumptions underpinnign the
device's fire safety.

HTH, Jan

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