over voltage protection

[andyf97]

Hi Guys, recently we serviced a few dead lasers after they had been some way connected to 380v ac.

is there a simple unit available that can sit and prevent anything other than 220 - 240 reaching the lasers.

I know there are power distribution boxes for current and earth leackages but I didnt see one for voltage?

let me give some examples:

380v connecting to the chasis of an another equipment
380 being fed into a 220 device directly or by earth and one phase

[Doc]

It would be much easier to invest some money in one of these

[Pitts]

Andy I think AOC make one, I have used them on highly sensitive equipment. They just look like a UPS.
I think its AOC I will need to look it up again. PM me if you need details.
Cheers
Ray
NZ

[heroic]

You can use MOVs in conjunction with miniature circuit breakers to produce this effect. If you put the MCB before the MOV (across the phases) then when the MOV goes into conduction above its protection voltage the MCB will trip.

[buffo]

Out of curiosity, who the heck uses 380V power these days? Isn't that left over from the early days of elevators?

I've seen 208/220/240 3 phase, and 440/450/480 3 phase, but where the heck do you get 380 from?

Adam

[Things]

Apparently 380V was old 3 phase?

And yes, MOV's are designed to do just this. Although usually they sacrifice themselves by conducting current, which in turn blows the fuse in your laser to stop the power. You have to replace the MOV every time it does this however.

[Doc]

Out of curiosity, who the heck uses 380V power these days? Isn't that left over from the early days of elevators?

I've seen 208/220/240 3 phase, and 440/450/480 3 phase, but where the heck do you get 380 from?

Adam

380v is the phase to phase voltage of a 220v system.

[buffo]

Ahhh... It's a 50hz standard... That's why I hadn't heard of it before.

Adam

[Things]

There's no 380V in a 50Hz system. Our 3phase is 415V.

[buffo]

Upon further research, it appears that the 380 volt system is only found in parts of Europe these days. It's a 50Hz standard, that much is certain. I can't tell if it's a delta-connected secondary with a neutral tap on one of the phases or a simple wye connected secondary where the phase-to-phase voltage is 380 though.

The delta configuration makes sense to me, as the 380 could be the top phase to neutral voltage - what we would call the "stinger leg" here in the US - on a 440V 3-phase delta system. But I guess it could also be the phase-to-phase voltage on a 380V 3-phase wye configuration, though in that case the single phase voltage would be rather low - around 208 or so... (Maybe that's why it's so uncommon?)

Adam