Supplying S7-300 with 230 V

[Maksio]

I guess there's no hope for me, but it's a long shot...

By accident I connected a S7-300 (CPU314C-2 DP) to 230 V AC power supply instead of 24 V DC. Obviously I damaged my hardware and my question is how bad it is...

Is there any way of replacing some fuse/diode on the PLC circuit board? I put the whole thing apart, but it seems there's no internal fuse. Now when I connect it to 24 V DC nothing happens...

Any suggestions/advices?

 

[Davek0974]

I would suggest it was toast

 

[shooter]

so you connected the good 24 Volts to the board, it will go to a diode and a resistor, and a big transistor.
just check where there is no 24 volt anymore. first to check is components with F (it is a small resistorlookalike fuse)

 

[dlweber]

Every experience I have had with ac being applied to dc circuit has been expensive disasters. I am thankful that I was not responsible in anyway for them.

Chances are it is dead, AC tends to flow at fairly high currents through many DC circuits. A main reason is Capacitors do little to nothing to slow down AC, but capacitors all but stop DC. That and almost 10x voltage thru anything that is purely resistive (resistor) will give you almost 10x current. I would assume that most parts inside the controller are rated for only 50V.

EDIT: by expensive the one was $30k the other was almost $1.5Mil. For your sake I am hoping you are not looking at a situation similar to either of these.

 

[Maksio]

 

[Maksio]

Anybody has a circuit diagram of this...

 

[dcp325]

Hi,

It looks like the small component on the right of the power connector would be the internal fuse, it's labelled as OMF 125 4A. It's a fast acting fuse, maybe the fuse protected the rest of the circuit.

 

[dlweber]

Circuit diagrams are becoming harder and harder to find especially for stuff like this. The companies don't make repair money if everyone can fix there own stuff, not saying it can't be found but I wouldn't get my hopes up to far.

I hope that fuse did its job (and more since it is only guaranteed to protect against 125V.) Let us know if that is the case.

 

[shooter]

hopefully it is indeed only fuse, so bridge it as you probably do not have it in workshop, and use external fuse (glass 5x20) of 2 amps
if it blows there is probably more broken like the capacitor
repair this one and try again.
and give the numbers on the both components for voltage control.

The interface is optoisolated from the rest so no worries .