The Inner Workings of Counterfeit FOTEK SSRs

Intro: The Inner Workings of Counterfeit FOTEK SSRs

Dec 2019 Update

• A lot has happened since writing this article in early 2015. We no longer buy FOTEK SSRs for any of our controllers. While I believe that FOTEK SSRs are great for lower current projects and I would not be afraid to use one for any project drawing 10 Amps or less, all of our controllers are rated for at least 20 Amps.

• We no longer buy any SSRs through Amazon or eBay regardless of the brand. I've discovered that even major names like CRYDOM and OMORON are subject to counterfeit sales through Amazon and eBay. So, these days we only buy directly from a few Chinese manufactureres or trusted importers.

• Yes we still buy Chinese manufactured SSRs. The counterfeit issue we all deal with is caused by greedy Americans, including greedy Chinese Americans, willing to make a quick profit at anyone's expense. China is just one major manufacturer willing to make whatever we are willing to sell.

• We started buying only 45 Amp rated SSRs and have been for a while, and the reason is simple. The TRIAC in lower current SSRs will be mounted to the base with the a screw while the TRIAC in higher current SSRs will be sweat soldered to the base. Flipping the SSR over to verify the screw hole is not there is quick assurance that we really received what we paid for.

The Original Article

Not too long ago we had a serious warranty issue with some of the controllers we manufacture. The controllers were passing test and would initially work for our customers, but would eventually fail. And these failures occurred after a long run of controllers that did not fail, so I knew that something had changed. We have used FOTEK SSRs in our controllers from day one and they have been very reliable until now. One change we made was we switched from buying directly from a known Chinese supplier to buying through USA based suppliers selling on Amazon.com. I had been watching prices for a while and my cost through Amazon.com dropped to close to what I was paying for parts direct from China.

Suspecting that the SSRs I bought through Amazon.com was the problem, I broke apart a 25 Amp rated part and a 40 Amp rated part and what I found surprised me. I actually expected junk but both SSRs were built very well, but they were both built with under-rated TRIAC's. For reference, the TRIAC is the part that actually switches current on and off inside your SSR.

The 25 Amp SSR was manufactured with a BTA12-400C TRIAC. I did a quick online search and discovered that the part is rated at a continuous load of 12 Amps and a non-repetitive load of 126 Amps. In other words, the TRIAC used in the 25 Amp SSR is only rated for 12 Amps! Here's my BTA12-400C Google search

The 40 Amp SSR was manufactured with a BTA20-600C TRIAC. I did a quick online search and discovered that the part is rated at a continuous load of 20 Amps and a non-repetitive load of 200 Amps. In other words, the TRIAC used in the 40 Amp SSR is only rated for 20 Amps! Here's my BTA20-600C Google search

I did a third search on FOTEK SSR counterfeit and discovered This Article as well as hundreds of forum conversations claiming counterfeit. And even though some of the counterfeit claims are likely failures caused by improper installation, apparently counterfeit SSRs are quite a problem! My next question was - are there even legitimate FOTEK SSRs out there? Yes there are and here is their Web Site. And BTW, I'm not just picking on FOTEK or Amazon.com. If you decide to buy any brand SSR from any online supplier including Amazon, eBay or "Joe's SSR Shop" not licensed to sell the product you are basically making a "shot in the dark" purchase.

I mentioned earlier that even the counterfeit SSRs were built well. All of the soldering was high quality and the TRIAC was properly mounted to the back plate with plenty of thermal grease. I suspect that these counterfeits are nothing more than lower current models re-labeled as higher current models. If this weren't so I believe the counterfeits I disassembled would be poorly built. There is a huge financial motivation to do this. Lower current models cost less than higher current models and any re-labeled product would result in instant extra profit!!!!

After this discovery I immediately went back to buying directly from my Chinese supplier and except for an occasional controller, the failures have disappeared. I have not broken apart one of the SSRs that work, but based on the difference in performance it's obvious that there is a internal difference in these parts.

You can find more information about the controllers we manufacture with these SSRs on Brew-Control.com or in our Amazon Store.

STEP 1: What If You Are Already Using a FOTEK SSR or Are Designing Your Own Controller?

If you have been using your SSR with no issues for a while then most likely you have a good one. FOTEK is a well known name in China and a good product and your SSR should continue working for a long time.

What should you do if you are designing your own controller?

Should you buy something other than FOTEK? I'd say not necessarily because FOTEK SSRs are a great value compared to anything you can buy from a USA name brand supplier. For example, a 25 Amp rated Crydom SSR will easily cost you $40 or more, while a 25 Amp rated FOTEK SSR will cost you less than $10 through eBay or Amazon. The best solution is to 'assume' that the part you buy has been re-labeled and buy a SSR with higher current rating than you need. Buy a 40 Amp SSR to control a 20 Amp load, etc. The cost is not much higher and you still purchase a quality part for far less than a SSR you would buy from a USA name brand supplier.

Or you could just buy a name brand like Crydom, but with counterfeits so common these days how do you know if your eBay sourced Crydom SSR is real or counterfeit? You don't!

The best solution if you are buying one that has to work is to "bite the bullet" and buy your SSR from a licensed distributor like digikey.com. A Quick Digikey Search for Crydom 25A SSRs returns a selection in the $41.00 and up range.

You can find more information about the controllers we manufacture with these SSRs on Brew-Control.com or in our Amazon Store.

Tom - www.kegkits.com

Comments

[Emirikol]

Hello i have a Fotek SSR-50 DA, it's fake almost sure, i'm trying to use it to drive a 220v heat bed for a 3d printer but when i plug the AC part i got almost 120v between terminals instead 220v, of course i got 0 when turned on, but it looks poorly isolated of something because as i said instead 220v when the relay is off i got 120v, did you find a issue like this before? Thanks (I'ts a 1000w 220v silicon heat bed)

[Tom Hargrave]

A SSR is never 100% on or 100% off and depending on the load you will always have some voltage across the SSR and some voltage across the load. And 120V across the terminals might be right depending on what's wired across the output.

Full on, you would expect 0.5 - 1.5V across the SSR with a load across the output. Full off, you would expect full voltage - .5V - 1.5V (218V - 220V) across your SSR.

But no load changes everything, you will always see 220V between your output screw and the other side on or off with no load.

[Emirikol]

Thanks for your reply, my surprise is because I can’t get a “fully open switch” I mean the relay have a DC side that work as trigger and a AC side that work as switch if I got 0v dc on dc side I should get a open switch on ac side and then approx 220v between AC terminals and if I put 12v on DC side I should get a some kind of closed switch on AC side and get much less than 220v (ideally 0) isn’t it?
My problem is that I got 0->120 and 12->0 so my circuit is never “open” just half open.

[Tom Hargrave]

What size load are you running and what is the SSRs current rating?

[Emirikol]

SSR50 is "rated" for 50A but i use it for a 1KW(220v) silicon heated bed so it support less than 5A

[Tom Hargrave]

Then you might have a bad SSR. The only way to know for sure is to replace it.

[nedfunnell]

I just blew up an 'AOLE' brand SSR, apparently by going over voltage rather than over current. It was passing 11A (40A rated part) but at 242v (250v rated part). Failed in the on state. I'll have to crack it open to see what's in there.

[Tom Hargrave]

I'm not familiar with the brand so I looked them up. At least they are a good looking part.... Since my article I discovered an easier way to judge the part's current rating. I found out that the lower current TRIACs are mounted with screws while the higher current parts are sweat soldered to the base. The higher current parts need the sweat solder bond you can't get with thermal compound. It would be worth looking for a threaded hole on the back side of your failed SSR before breaking it apart.

[teledog]

Just got a "Fotek" from eBay ..supposedly 40A??

Blew at <25A

opened it up ..was a BTA16 (16Amp)

[ElFantastic0]

For what it's worth, I did a similar teardown of a failed fake SSR60-DA on my awful neglected pretend blog:

http://epicbeardquest.blogspot.com/2014/10/how-to-...

I agree that it's relatively simple and inexpensive to design your own SSR's from triacs or SCR's; however, there are a number of appnotes relevant to addressing component selection and protection that are perhaps better than blindly grabbing a schematic from GIS.

Use and protection of triacs:

http://www.littelfuse.com/~/media/electronics/appl...

http://educypedia.karadimov.info/library/6785.pdf

http://www.datasheetcatalog.com/datasheets_pdf/A/N...

http://www.onsemi.com/pub_link/Collateral/AN1048-D...

Using & snubbing optotriacs:

https://www.fairchildsemi.com/application-notes/AN...

https://www.fairchildsemi.com/application-notes/AN...

Direct gate drive circuits:

http://www.st.com/web/en/resource/technical/docume...

Lastly, if you do decide to roll your own, be aware that there are counterfeit triacs on ebay too, and they'll give you just as much trouble, if not more.

[Tom Hargrave]

Thanks for the great references. Based on what I read, if I do design my own SSR it will be with one of the snubberless TRIACs rated for at least twice the line voltage I'm switching. One of my motivations for "rolling my own" is I can build the SSR directly onto the heatsinks I'm using, eliminating one thermal resistance layer.

In the mean time I did find one brand that performs as advertised. They are PQLYT SSR - I order them directly from China.

[acheide]

Thanks for the heads-up I have bought some of these relays, but I think building my own would assure me of the desired rating. Here is one example.

[Tom Hargrave]

Just beware that the example you provided is designed around a 16 Amp TRIAC attached to a very thin aluminum housing. The amount of current that project will be able to switch will be limited to the watts dissipated by the TRIAC - about 1.5 watts per Amp and the ability of the housing to radiate that heat away. Assuming the SSR itself does not fail, all the components inside will be cooking at whatever temperature the housing settles to.

My "best guess" is this one is good for up to 5 Amps based on the housing. A larger housing is better, a finned heat sink is even better and a fan cooled finned heat sink is best - all depends on how much heat you generate!

[69fordf100]

Thanks for finding this. I was building an automation setup and was thinking of using the foteks. On my budget, I'll buy the higher rated ones. Thanks again

[Tom Hargrave]

You'll note from the article that I am not against FOTEK SSRs. I believe that the counterfeiters have taken advantage of and are profiting from their popularity. One point I made is even the counterfeit SSRs were well built. And based on what I found I would not have a problem using them if I had to, I would just use a higher current SSR than my project called for. But fortunately I can buy direct from China and I've never had a problem with the SSRs I've bought direct.