Usage Of Fuse For SPD(Surge Protection Device)

Fuse 1 protects the equipment, fuse 2 is just there in case the SPD shorts, so that fuse 2 will clear instead of fuse 1 and the equipment can still remain operating (just without the SPD protecting it any longer).

Yep, F2 protects a Metal Oxide Varistor based surge arrestor device shown on the drawing and is used because the MOVs have a tendency to fail in a short circuit condition when they reach the end of their life. The F2 fuses are there to ensure they are removed from the circuit if they do rather than operating any upstream protective devices (such as F1).

thanks, then fuse 2 does 2 works:

1- protecting spd from short current

2- not stoping equipment

am i right?

and please give me a reference for this for studing

thanks

Well, "protecting the SPD from short current" is not really what is going to happen. There is nothing "using" power in that circuit, so the only time you will get short circuit current is AFTER the SPD fails, so technically, F2 is not protecting the SPD.

thanks a lot. could you give a reference about fuse2 usage please?

Here is a good reference book that is pretty much the comprehensive surge protection and lightning protection design guide (in my opinion anyway). It includes details you are asking about on the fuses and its free.

DEHN

<...a reference for this...> The designer's name will be on the wiring schematic drawing from which the installation was created. Ask this individual.

<...fuse 1...> is the circuit protective device, preventing fires developing in the cabling to the equipment in the event of a fault developing thereon.