UK RCD before a 230v/24 PSU?

[bob6459]

Hi all

I have seen a schematic drawing for a control panel recently where they (whoever drafted the drawings, designed the panel) show a RCD before the 230v/24v dc PSU, and the PSU is the only device downstream of the RCD

in my mind this has no merit. The 24v secondary d.c side of the PSU supplies electronic circuits

would you guys agree that the RCD is this instance serves no valuable function?

thanks

 

[pc1966]

would you guys agree that the RCD is this instance serves no valuable function?

It depends, but in many cases no.

If the power supply has full safety separation (PELV, etc) then probably not, but it also might depend on any other risk factors that might impact on isolation: such as operating in an environment with the risk of water leaks, extreme condensation, or conductive dust, etc.

Also in might depend if the RCD is for the whole system and in a separate double-insulated box as it is part of TT earthing for the control panel, and serves to protect against cable damage on route to the PSU, etc.

TL;DR it needs a bit more context

 

[bob6459]

It depends, but in many cases no.

If the power supply has full safety separation (PELV, etc) then probably not, but it also might depend on any other risk factors that might impact on isolation: such as operating in an environment with the risk of water leaks, extreme condensation, or conductive dust, etc.

Also in might depend if the RCD is for the whole system and in a separate double-insulated box as it is part of TT earthing for the control panel, and serves to protect against cable damage on route to the PSU, etc.

TL;DR it needs a bit more context

many thanks

the earthing system is TN-S

the RCD is inside the control panel and has only the 230v/24v PSU connected to it

my other thought is the RCD nuisance trips and then the 24v d.c is lost. There are solenoid valves, pressure sensors etc in this design along with PLC control for such sensors.

I just do not see the reason the placing an RCD at this location (electrically speaking)

thanks