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It’s likely a negative temperature coefficient device used to limit inrush current into the bulk storage capacitor and prevent fuses blowing or breakers tripping. It’s quite a common thing to implemen …

they have not mentioned the value like 4kV, 6KV No they don't need to. EN 61000-4-5 specifies various different voltage levels and it is down to the designer to select the one that is appropriate an …

Who says it's a class 2 device? Who says class 2 is 2 kV? EN 61000-4-5 says this about the voltage impulse: - So a level 1 device would survive a 500 volt surge and this translates to a surge curr …

What does this symbol mean in the internal circuitry of a surge protector device? It's a spark-gap or gas discharge tube (GDT): - Image from here bonus love for its functionality in this circuit a …

Not really - it all depends on the state your battery was in at the time. If the battery had been previously discharged to some degree then plugged in, it is likely that the laptop will exhibit a diff …

Since this is indirect lightning and has a fast waveform, should the tvs diode be slightly above the Impulse Sparkover voltage? If the TVS breakdown voltage was above the GDTs impulse sparkover …

The data sheets are telling you this: - The device will conduct 1mA somewhere between 47-10% and 47+10% at 25ºC At 5A the voltage across the device will be no more than 93V (this is a pulse test) Th …

I'm not sure you are comparing apples with apples on this. The RS485 device is undoubtedly more powerful and clamps to a lower voltage than the USB device: - SM712 clamp voltage at 5A = +20V and -10 …

A few pointers: - The surge generator will have a defined output resistance that is stated in the specification of the surge you are trying to meet. This output resistance may be enough to avoid addi …

Something else I've not considered? Think about what ethernet has that most other data comms don't have; namely, the magnetics: - They provide surge voltage isolation. Picture from this Farnell dat …

So what am I missing? How can a transformer protect against high voltage surges from the outside? That is not how lightning generally inflicts itself on telecom cables (for instance). Typically …

Using the data sheets of a more reputable supplier (Littelfuse for instance): - What does it mean that MOV has Varistor rms voltage of 680 V It doesn't have an RMS voltage rating of 680 …

Yes the device's being tested in regards to IEC61000-4-5 surge testing In that case you need to know the surge voltage series impedance that is appropriate for your device. The appropriate series …

It's called inrush current limiting and works by allowing the capacitors to charge to close to their peak voltage value via the 10 ohm resistor. This limits inrush current when the capacitors are full …

This didn’t fix the issue. Is a varistor with a crack in the case a sign that it’s also toast? It's not a good sign and it may well be broken but, given that both varistors mentioned are across the …