Need a hermetic sealed high current relay

Kilovac. Or Gigavac. Big bucks.

Or a power reed, although I don't really trust them for reliability.

Why not a solid state relay?

John

How about this one ?

Just put the relays in a plastic bag. Silicon seal where the wires come out. Recall that leakage requires a pressure differential, and none occurs through the seal. The bag shinks to equalize the ambient pressure. Ken

We have been using a solid state relay (two N-channel MOSFETs in anti series connection), but they get too hot and we need terrible derating if they are to survive a high current surge.

So our approach may be to use a Triac to turn on the product (motor) and energizing the relay at the same time (so the relay takes all the current after 1 mains half-cycle (10ms). Likewise when the motor is turned off, the triac is turned on, the relay turned off and the the triac turned off again (so the relay never actually breaks a current)

Moreover the solid state relay costs 8 USD, so we hope to find a cheaper relay than that

regards

Klaus

On a sunny day (Thu, 6 Dec 2007 13:57:22 -0800 (PST)) it happened Klaus Kragelund wrote in :

I have seen potted electronics that had water in them (porous), they failed. Copper oxide, all green, traces broken, a big mess. Unless it is for very shot duration (some hours, and not even salty water, or any not purified water sounds like asking for disaster to me.

I don't know how well these would perform but they cost above $20:

Digikey has them. Theirs are not rated for EU voltages though, all US (120V). I would contact them about it, plus maybe some other relay companies like Weidmuller, Panasonic Electric Works, Phoenix, Potter&Brumfield (now a Tyco division), etc.

Also, you could check with folks from undersea exploration businesses (submarines) and oil/gas exploration suppliers.

These guys know a whole lot about this stuff:

We have field test trials submerged under pressure that has run for about a year now. No problems yet :-)

its a matter of finding the optimum potting compound that will glue onto the parts and PCB (VDE demands a sticky test - if I use the correct termI hope)

Regards

Klaus

Reed or Vacuum relays.

Most likely a Reed type will work for you.

As others have stated, reed relays are usually glass/metal sealed and can be potted without mechanical interference. There are also mercury relays that have all moving parts inside a glass capsule.

Reed relays that are suitable for motor switching might exist, but the usual uses are small-signal; a 2A motor will require contacts rated at higher than 2A...

I've seen mercury contactors, but they have to be kept vertical, and I'm only ass-u-me-ing that they're waterproof, since they seem to manage to keep the mercury inside. :-)

Good Luck! Rich

Those might be off limits by now. Probably even more so in Europe.

On a sunny day (Thu, 6 Dec 2007 15:40:05 -0800 (PST)) it happened Klaus Kragelund wrote in :

Oh, I see, if it sticks then it is like a coating. Still personally I would avoid it :-)

Klaus Kragelund snipped-for-privacy@hotmail.com posted to sci.electronics.design:

Probably a tad expensive but would something like this do what you want?

From an item on the first page of a google search of: hermetically sealed relay

Oh boy! It is rated at a whole TEN AMPS!

Why not try a SOLID STATE relay, and pot the thing in something that will NOT allow water to infiltrate, like a polyurethane potting compound, like Conap EN-12 or such.

Water still creeps between the silicone and the wires (IFAIR a remark from a mechanic that maintained well logging equipment, although we are talking 300-400 bar @100 degrees Celcius here)

Wim