The article mentions 8/20 surge pulses as 8ms/20ms. That's wrong. The time scale is in microseconds. A pulse of 8kV with 20ms decay is a *very* large energy. TVSes are capable of absorbing power up to 400~5000W, depending on the model, but a 20ms pulse would require a much larger device.
Surge? "An uninterrupted voltage increase that lasts more than a few seconds is usually called a "voltage surge" rather than a spike."
Nice article about Transient protection, what about the surges. Try 150% for 1/2S (with a profile). Now thats a surge.
Personnally, I like my circuits fried with a touch of tobasco sauce.
Seriously, you need to put protection on all of your inputs or pay the consequences. Regardless of surge or spike, over voltage destroys semiconductors in femtoseconds.
Anyone remember the old UV erasable proms? I could destroy one from five feet away just from the static charge I would build up walking over the tile floor.
Zaap! It's done.
Only thing missing is an inductor in place of or in series with the resistor. Allows for much more energy withstand. fulcrums energy from (referenced in voltage)shunt protection downstream to GDT via inductor voltage rise due to di/dt. Care must be taken to not saturate core, air gap recommended.
I have found that allowing the entire voltage supply (including 0 Volts) to float enables the circuit to float around any surge/spike.
In this case, there are a number of capacitors connecting various voltages, inputs and outputs to the real ground.
A device I use lots of is the good old Pi Filter (or capacitor input filter) on every power supply rail, input and output, along with extra series inductors - everywhere.
To date, I have protected uProcessors, and low voltage electronics (5 Volt, 12 Volt) successfully against voltage discharges around the 8 MV mark (we have electronics inside an Ion Accelerator).
Warning - do not use MOVs as when they fail, they fail short which will require replacement. Use protective devices that are self recovering so the protective components do not become part of the problem.
Point taken about MOVs, but they are capable of absorbing a LOT of energy, even if they fail shorted. I used to live in Zimbabwe, which has bad lightning during the summer. A company I dealt with there used big MOVs in their mains surge arrestors and they worked a treat. Better to replace a $ 35 mains surge protector than a TV/Video installation.
Same company did some tests and found that a knot in the 3-core mains supply cable provided a lot of protection as well - added inductance. I used to knot all my cables after that and never had a problem with my mains inputs.
Good. Is there any difference between putting 2 unidirectional TVS and a single bidirectional TVS? I usually use 2 uniderectional but frankly have no idea if a single bidirectional has poorer. Agree also to add air core inductor in series with the resistor,
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