Surge protector

Somehow you think a little ferrite is going to stop a destructive surge? Start with specs for that ferrite bead or rod? At what frequencies does it even start working? And how much impedance? Up front, you must put numbers to your transient and to what is going to stop or block that transient.

Lets use a toggle or keyed panel switch as example. Typically, switches are rated for 20K volts. However I touched one, static shocked it, and crashed the computer. Human body should not generate more than 20K. But that 20K isolation spec has conditions - default knowledge. One does not typically stop or block transients. Transients are diverted. If the static shock or transient occurs, nothing was going to stop it. We avoid failures by diverting.

That switch body was isolated from metal chassis by epoxy paint. Solution - an internal washer was required to ground that key switch, through paint, into metal chassis so that switch could withstand 20K volts.

Same applies to your sensor. Solution is to divert a transient so that transient does not have both an incoming and outgoing path through sensor. That means incoming path must make some path to what the surge seeks - ground. This path is either by a direct connection (ie the internal washer and metal chassis) or by making same connection via a surge protector. The latter is necessary when a direct (hardwire) connection cannot be made. The latter must also consider other parameters such as let-through or threshold voltage, parasitic capacitance of that protector device, and isolation voltage at sensor so that voltage will pass through protector and not through sensor.

Basic concept. One can build a dam and see transients (floods) overwhelm and destroy same. Or one can build dikes to divert flood downstream. That is how transient protection is installed. Any transient that has an incoming path to sensor, but does not have a good outgoing path from sensor, will not pass through or damage sensor. You must provide path for destructive transients that does not pass through sensor. Trying to stop a transient with a ferrite rod and looped wire is - well look at the numbers. You would be only fooling yourself - and not the transient.

Your sensor must be pr> How do i add a surge protector to a sensitive device (AC powered

thanks tom, for the point, I'll look into it...

Thanks!