0
\$\begingroup\$

I am looking for a small relay to help me with network cables. The system needs to be able to withstand a reasonable electrostatic discharge on the cables. I am using MAX485 network chip, which has 15kV ESD protection so I guess that is a reasonable threshold. The relay I am looking at is Omron G5V-1-5VDC (non-latching). Its datasheet doesn't mention ESD. In fact, I looked at several similar relays from other manufacturers and they don't mention ESD either. I am guessing it is not an issue for such relays? Would it let a 15kV ESD through without burning down?

\$\endgroup\$
4
  • 1
    \$\begingroup\$ Dielectric strength is 1,000 volts AC between coil and contacts. Could an ESD discharge damage the dielectric properties? Not sure. \$\endgroup\$
    – Andy aka
    Feb 5, 2020 at 12:12
  • \$\begingroup\$ I'd be very surprised if a normal ESD event damaged a relay. It's a coil of wire and a switch - can you damage inductors and switches with ESD? \$\endgroup\$ Feb 5, 2020 at 12:22
  • 2
    \$\begingroup\$ @user253751 it's possible for a high voltage breakdown between coil and some other metalwork (frame, switched circuit) to compromise the insulation on the coil. Unlikely there's enough energy in an ESD test; hopefully something else (varistor? ) defines a charge path that breaks down first. Which is probably why datasheet doesn't mention it. Using relays for HV applications is a different matter of course. \$\endgroup\$
    – user16324
    Feb 5, 2020 at 12:58
  • 1
    \$\begingroup\$ That is why I specified "normal". I'm sure you can damage anything with enough gigavolts. You won't break it by touching it with your finger, no matter how long you rub your shoes on nylon first. \$\endgroup\$ Feb 5, 2020 at 13:02

2 Answers 2

2
\$\begingroup\$

The coil is fairly invulnerable to normal levels of ESD because its impedance is low enough to offer an easy path to ground for the miniscule currents in a typical ESD discharge. The contacts would likely take some ESD damage if they were to arc, but it would be negligible compared to the arcing they would see in normal operation...relay contacts are designed to tolerate a whole lot of arcing before they start to show serious negative effects from it. So ESD tolerance isn't usually included on mechanical relays, since it generally has little effect on their operation.

Solid state relays are another matter.

\$\endgroup\$
0
\$\begingroup\$

A mechanical relay is basically a piece of steel and copper so no, something with the power level of an ESD discharge would not be able to damage it. You take ESD discharges all the time and you are just a blob of flesh. The type of arcing discharge that would damage steel and copper would be the kind that would burn you. When was the last time you had an static shock burn you?

\$\endgroup\$
1
  • 2
    \$\begingroup\$ A relay may be damaged without damaging steel and copper. Punching a hole into the thin isolation of the copper wire may do. Low voltage relay coils are not built the same way as high voltage transformer windings. \$\endgroup\$
    – Uwe
    Feb 5, 2020 at 16:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.