Surge Protector UC Value

[MJCM]

I have a question about the UC Value of Surge Protectors.

 

You can get UC = 400 or UC > 420 but also UC = 275V

 

Which one is better to protect your equipment?

 

Or is the kA value leading in this? The higher the kA the better?

[Crossy]

The Uc is the maximum operating voltage (RMS or DC), Littelfuse recommend that it is at least 110% of the maximum expected voltage.

 

275V would be right on the line in Bangkok (MEA is nominally 230V).

 

Choosing a Uc that's too low would mean that the device triggers more readily which really isn't the best idea because they do wear out.

 

All our AC ones are actually 385V which seem to be doing their job adequately.

 

The kA rating is an indication of the amount of surge energy the beast can absorb, generally the higher the better.

BUT

The bigger devices tend to have a higher clamping voltage (Up) so it's advisable to employ smaller ones on your branch circuits (or plug-in ones) to mop-up any remaining dregs that the big chap has missed. 

 

 

[MJCM]

Thx.

 

16 minutes ago, Crossy said:

All our AC ones are actually 385V which seem to be doing their job adequately.

But wouldn't that, in case of surge higher then let say 300V, be disastrous for your AC equipment in theory?

 

Edit: I am looking for 275V ones but the ones I find are only 20kA and I would like 40kA>

(Maybe my Google f.u. isn't that good ????

[bluejets]

On 9/18/2022 at 9:59 AM, MJCM said:

Thx.

 

But wouldn't that, in case of surge higher then let say 300V, be disastrous for your AC equipment in theory?

 

Edit: I am looking for 275V ones but the ones I find are only 20kA and I would like 40kA>

(Maybe my Google f.u. isn't that good ????

Read Wiki on the subject, plenty of details there on what is what.