(6) New Crydom 25 Amp Solid State Relays - $22 each w/free shipping

[brads]

I have 6 new Crydom Model D2425 Solid State Relays for sale. These are rated for 25 amps at 24-280 Vac, and take a logic (on/off) input signal of between 3 and 32 Volts DC. They are brand new in their original boxes. The boxes are a little scuffed up from being on a shelf for years, but they aren’t bad. The SSRs inside are perfect.

$22 each with free shipping, or a flat $100 gets you all 6. I paid twice as much when I bought them years ago, but I don’t use this size any more, so my loss is your gain. Both Allied and Newark Electronics sell this model for $41 each.

Brad

[neddowerx]

What would one use these relays for? Kilns?

[brads]

Yes. They work pretty much like a standard contactor or relay but are much more reliable as long as you don't mount them where they can overheat. In other words don't mount one on the side of your annealer. There are also some other considerations that I won't get into right now.

As an illustration of the difference in reliability when installed right, a normal electro-mechanical relay running at 50% power, 24/7 on a 30 second cycle time (about the shortest they should be run at) has an average estimated operational life of just a few months - or less.

Running at a cycle time of 1/60th of a second (the shortest possible on 60Hz AC power), 24/7 at 50% power, an SSR has an estimated average life measured in hundreds of years.

But if you need to ask that question, these probably aren't for you anyway.

[oG Glocc Coma]

Brads, you have seen how my SSR fit into my Kiln sitter box. Do you believe the SSR you sent me would be more reliable if I bought a "project box" to finish the Digital controller and set it to the side of the kiln rather than directly on it?

[brads]

Yes. Electronics - including SSRs - do not like excess heat.

[PyroChixRock]

But if you need to ask that question, these probably aren't for you anyway.

Better safe than sorry. I was wondering the same thing at first, or more so if they would fit my kiln. And I'm even brave, I've changed my own relay before. Yes, that's brave!! I'm a glass blower, not an electrician and wires kinda scare me.

I have an extra relay so when I have a chance later tonight I'm going to go look at see what it is. If these are the same I'll take two off your hands. Or if they'd work in my kiln; I have an aim 9169 or whatever it's called, and a paragon f130 elite. I'd like to have them sitting on my shelf collecting dust next to my other one. You know, that whole better safe than sorry thing.

[oG Glocc Coma]

have them sitting on my shelf collecting dust next to my other one. You know, that whole better safe than sorry thing.

Yea, learnin that the hard way. Changing out my SSR tonight and will probably get another one when i get some extra cash!
Thanks Again Brad!

[brads]

Yes, spares are good. Just don't get as carried away with it as some people...

[brads]

Yea, learnin that the hard way. Changing out my SSR tonight and will probably get another one when i get some extra cash!
Thanks Again Brad!

When you mount it, use heat sink grease, AKA: "thermal compound" on the base. That will help dissipate the heat generated. Your local Radio Shack should have it. Thermal pads that do the same thing are also available, and aren't as messy as grease.

[oG Glocc Coma]

Are those ramp and soak Digi Controllers?!?!

If so can I talk you out of one of those controllers around Feb?!?!?!

[brads]

Are those ramp and soak Digi Controllers?!?!

If so can I talk you out of one of those controllers around Feb?!?!?!

Yes, most of the controllers you see in the photo are Chromalox 2104 controllers. They can do a 16 segment ramp/soak profile. If you get a little creative you can break up the 16 segments into a few shorter profiles, but it's kind of a pain. The majority of them can be used with either a regular relay or an SSR, depending on how an internal jumper is set. These are my "go-to" controller, if you can't already tell from how many I have, lol.

Seeing as 15 or 20 of them (I have more that aren't in the photo) might be a few more than I really need, I'm sure you can find a way to convince me to part with one.

[RamblezMarblez]

What are them books like Brads?

[brads]

One is the 1992 printing of Woldemar Weyl's "Coloured Glasses" in virtually new condition. The other is my 1946 edition of "Modern Glass Practice" that has an inscription by Sam Scholes (the author) to Van Derck Frechette, another Professor of Ceramics at Alfred University whom he gave it to as a gift. I was thinking about selling it, but doubt anyone would want to pay what it is worth to me. (I lived in Alfred before moving to Georgia and acquired the book from Dr. Frechette's wife after he passed away.)

I'm also thinking about selling "Coloured Glasses" but am trying to find out if it is out of print before I do. I think it is and if so, that will obviously impact the price. (I'm pretty sure I sold my other one recently for about half of what I should have...)

[Greymatter Glass]

...don't make me post pics of my electronics piles.

At their rated loads SSR's are designed to be run with a heatsink (and sometimes a fan, you have to refer to the documents). If you run them well under their rated loads you're usually ok, but if you're drawing like 15-18A of 110 through those constantly that will shorten their lifespan drastically. 25A at 240V without a heatsink, they'll last 2 or 3 minutes before they fail (possibly dangerously so). Living Glassworks kilns made by AIM all had SSR's and they used SSR's. I replaced mine with this exact relay, been working fine ever since, but it's on a proper heatsink with fan. My previous relay failed because it wasn't properly mounted to the heatsink.

That said, Crydom is one of the best brand SSR's on the market, and I'm considering offering you $100 for the lot. They shouldn't be considered a direct swap-out replacement for a mechanical contact or mercury relay.

[brads]

I agree. A lot of that being the "other considerations that I won't get into right now" that I mentioned in my earlier post. Basically, I didn't want to get too deep into things if no one showed any interest in the SSrs. I also figured that 95% of the people who might be seriously interested in these would know most of it already. But for those who don't...

Heat sinks - good. Fan? At high power draws - good again, to be safe. I used a fan blowing on the heat sinks of the SSRs on my glass furnace during the summer in NY. In winter it was cold enough in the shop that the fan wasn't necessary. I never lost an SSR on the furnace. Mine were over-rated by about 50% as well - 125A SSRs on a furnace with a max draw of roughly 80A when run at full power with new elements. (Although I never ran at full power with new elements.) The SCR I use on my glass furnace here in Georgia has an integral fan. Because the SCR is rated right at the max current draw of my furnace (80A), I still worry just a little in the heat of the summer, but haven't had any problems with it.

Too much heat - BAD! Too much power - Bad! <----(Caveman explanation.)

Mounting an SSR to the side of an oven is asking for trouble, heat sink or not. It annoys me no end that manufacturers love to mount EMRs and mercury relays to ovens to save a few bucks. These may not be as susceptible to heat as an SSR, but it can still affect them. I've seen enough posts from people complaining their relay prematurely died to wonder how much longer life they might have got (gotten?) if the thing had been mounted away from the heat.

The SSRs I have for sale notwithstanding, my advice for anyone having trouble with an oven relay would go in this order:

1) If it's an electro-mechanical relay - as most are due to cost - replace it with a mercury relay. ALWAYS choose a bigger relay than the amperage rating of the kiln/oven. If you have a choice between two otherwise identical models for nearly the same price, go with the larger one.

2) Take it off the damned oven and build a separate control box to keep it cool. (And do the same with your temperature controller.)

3) If you need tight temperature control and understand what you're doing, use an SSR or SCR for power control. Make sure you have a positive on/off switch to kill power to the elements. SSRs and SCRs leak enough electricity to hurt you even when they are "off".

End of mini-rant...