A camera will be mounted outside and powered via POE to Aruba 2540 network switch. I don't want indirect lightning surge to travel into the network switch. I don't care if the camera gets destroyed.
The ethernet line to line voltage is 54V, and the requirement that I have is that the TVS should clamp lighting surge upto 2000V or 400Amps.
What kind of circuit would I need for lightning protection with a TVS?
Best Answer
A TVS diode is probably not going to be enough to protect your equipment from a surge caused by lightning. Generally you'll want to use gas discharge tubes to take the brunt of the surge, then either inductors or dedicated Bourns TBU surge protectors, followed by TVS diodes to minimize the residual surge. Here is a fairly standard surge protection scheme that is used all over the place for exactly this purpose:
Obviously you'll need to change the values of the TVS diodes, but this should give you an idea. Also, if your system doesn't mind a slightly higher series resistance, replace the inductors with TBU surge protectors, as I mentioned earlier.
EDIT:
Note that this is a double-sided protection circuit, meaning it can protect against surges from either direction. If this protection circuit is to be placed right next to the device which is to be protected, you may eliminage L3, L4, and SA2. Keep TZ1, TZ3, and the earth connection between them though. The device being protected should then be connected where L3 and L4 used to be, across TZ2 and TZ3.