REAL VS FAKE SSR
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- เผยแพร่เมื่อ 6 ก.ย. 2024
- After a friend had a close call with a counterfeit solid state relay, I decided to tear down a known counterfeit and a known legit SSR to compare them. I also gloss over the differences between SSRs and mechanical relays.
I am supposed to link to AVE's video where a drill won't stop because of a dead MOSFET, but I can't find it at the moment.
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Mechanical relays will fail closed fairly often. If you check out a lot of old furnace boards and appliance boards, you’ll see charred contacts and melted solder under the relay. Which means the contacts degraded, or there was a large current spike welding them together… And allowing an overload condition. I see it quite often come through my lab
+1
I've never had a solenoid failure on 2 hp relays leaving the circuit open on induction motors (pool equipment) in 10 years. They ALWAYS fail closed due to basically spot welding themselves due to the inrush current, or where the AC cycle is on the sine wave when the contacts close. At or near max positive or negative will cause the contacts to arc and weld over time. Its crazy how much amperage an induction motor will draw a startup (basically full slip). If a motor is rated at roughly 15 amps, it will draw close to 40 at start up
Adding to that, an inductive load is quite complicated when turning it off, as it will tend to arc when disconnected. I imagine a motor will be fine on a relay until a certain point where you'll definitely need to go with a proper contactor.
There are many Fotek knock off relays out there. Fotek trigger at 4v minimum. If yours says 3v on the faceplate, then it is a knockoff.
The maximum ratings of electronic components such as triacs are based upon the component having a notionally infinite heatsink, so in reality a lot of derating or heatsinking is required or use a much higher rated solid state relay.
It's interesting how one of the relays featured here was the opposite way around regarding the specification in that it would make sense for a 25A triac could reasonably be in a solid state relay rated 16A. Personally, I run electronics with as low a load as possible to minimise heat generated and achieve maximum life. For a solid state relay, I think I'd be happy running maybe 30-40% of the maximum rating but definitely not more than 50%, although it does depend on the nature of the load and the exact specification of the SSR.
I had mechanical relays failing in closed Position, the contacts melted together despite they where original brand relays. The load was just about 3A to 4A and the relays where rated with 10A. I had to pull the relays out of their socket to shut the attached devices off. Maybe it was the inductance of a Motor that was the cause of failure, but I'm not sure.
Definitely it's the EMF
@@Airman.. Yes, it was probably the CEMF spike that welded the contacts together.
Relays used for motor appliances should be considered up o 4 times the rated load of the motor. in this case 10 amps is just under sized. Try using bigger relay, 15 or 16 Amp should be ok, or move to contactor
That's not a MOSFET that is TRIAC
I mean he corrected himself in the video description
it's wise to take the chinese amperage rating ALWAYS as a peak rating. or a good rule of thumb is to run no more than half the amps it's branded for.
Yuuuup! Even with brand name it's recommend no more than 80-85% for long term use if you want good longevity
Thanks for the vid! Just subscribed to your channel. Keep up the good work!
When you use a SSR for resistive loads, get one that has two times your needs (so controlling a 20W heater element, get a 40W SSR)
However if you are going to switch inductive loads (motors, AC, pumps, Solenoids) get six times the appliance rating! (so if you want to switch a 20W motor, get a 120W SSR)
For inductive loads it's cheaper to ust use a mechanical relay for such things
Hold on there.. most ratings on ssr are for resistive loads
I use a lot of these for kiln controllers. Rule of thumb... buy at least twice the amperage of your device. These Chinese things are not to be trusted. Most are over rated. Also the amount of current they can pass drops off with increasing temperature. So heat sink um good and try to get a fan in there to cool them.
The worst part of that is the bta16 is probably fake as well so may not handle 16 amps.
SSR's NEED good heat sinks and to be chosen properly. Always consider the printed current rating as a peak rating and RMS is 1/3rd of that even with name brands, and have a proper heat sink and mounting system that has good air flow.
Also most consumer bought SSR's are rated for resistive loads (heaters, lights (minus neon signs and fluorescent lamps), switch mode PSU's) not inductive loads (HVAC, power tools, and fans) especially if the load has a start and run capacitor. This is hard on the SSR's Triac and in time will cause the TRIAC to fail in interesting ways (one such way you described).
Thanks for this video...you get a like just for destroying the panasonic...must've hurt a bit...While its perfectly fine practice to stick to 80% of rating for even branded electronics...it's completely unnecessary. That is exactly what you are paying for with high-quality electronics, good engineering, accelerated wear testing, and built-in derating...honestly, if you derate by 20-25% its more likely that you are running at 50-60% of the specified max...once again totally fine (and even good for longevity) when you are doing one-offs or personal projects, but can definitely add up quick. Great video though!
There is no mosfet in SSR but a triac. And please use a zoom to better see what you are doing :-)
DC SSRs are mosFets, AC SSR are Triacs.
All electronic devices that you plane to run high current thru should always be attach to a proper cooling devices, that’s why you have a large bare metal surface on the bottom. That’s standard procedures! It’s the heat that is a result of high current which is no good for the components and is possibly a fire hazard. The components are rarely the problem it’s more often the poor soldering to the boards so called “coolsoldering” ie. the solderingmaterial didn’t fuse the component proper to whatever they are attached to which then results in poor friction and higher temp as a result. Almost all components no matter the brand is nowadays almost always done in a factory somewhere in China! :-)
Yes, but in this case it also had the wrong rating on the sticker compared to the mosfet. Technically you can run just about any component at a higher current if you cool it enough... But derating factors and the ability to withstand heat are necessary in real life.
Great video! I am wanting to buy an SSR for my 220v 3d printer heated bed.
So in other words, even if i end up with a Fotek 25A conterfeit, it would be safe for a load of 2.7a?
My conclusion was that they seem mostly well build but severely over rated. At 2.7A supervised, it seems reasonable. I would measure the temperature change / put a heatsink. If it warms up within a few hours, I'd go for something else. On a 3d printer, you should have no problem using a mechanical relay no?
@@Making Thanks for your answer. I am searching for a SSR of panasonic like in your video, i found one for a fair price . Will buy this one , rather be safe than sorry with all the counterfeits! www.conrad-electronic.co.uk/ce/en/product/505395/Panasonic-SSR-1-pcs-AQA211VL-Current-load-max-15-A-Switching-voltage-max-250-V-AC-Zero-crossing?ref=searchDetail . From what i read on the 3d printing forums only SSRs are used, can't remember why honestly :)
searched ebay and aliexpress but they don't offer panasonic ones in china to be sure, also pretty sure the conrad one is legit :) BTW, you got a new subscriber ;)
That's what I do as well. 3d printers can run very long unattended... It's different when it's for something like a diy spot welder where if it fails, you are right there to deal with it. Still, don't forget the heatsink on your new ssr! :) thanks and have a great day!
Interesting video but it would help if you zoomed in.
Your content is very informative..but you need to adjust the camera.. coz we need to see very neat and near.. just zoom if its available..thumbs up
True
Silastic is a trademark name for Dow Corning silicone rubber. I'd call any silicone rubber Silastic, but not urethane.
Thanks, I (mis)used it as a generic term for covering on electronics. Now I know.
I used to think that too, the only person I've heard use the word is AvE. The other day a doctor friend was telling me how there are medical implants made of Silastic and how nothing sticks to it. After that, I had to look it up.
That is indeed where I learned to misuse it! :p
Any reliable shops on AliExpress for the SSR-25DD or 40, 80 Amp versions. I only use it to switch a 1 Amp 1vdc fan, but i wouldt like a reliable real SSR.
just because its its not a Panasonic doesn't make it fake or counterfeit etc its probably even better than the Panasonic one if it looked exactly the then yes
There is wrong besides mislabeling. It's not electrically safe because of inferior isolation and poses fire hazard as well.
WHERE DID U BUY THE REAL ONE? ive been dying to get a rel one for my heat press
Digikey
Digi-Key as said before, or Mouser or Farnell. They usually stock directly from the manufacturers.
A mechanical relay can fail close if the contacts weld to each other....
That's fair, but in that instance you've probably had a power surge that also fried everything else as well, so the state of the relay becomes moot.
@@Making That depends, the surge could be the proper inrush current of whatever's switched. Might first lead to pitting on the contacts due to arcing (increasing resistance more and more over time) and then eventually weld closed.
It happens often in industrial settings.
That's when a contactor should be used instead ;) I didn't think of the pitting increasing the resistance, but I guess a lower contact surface and oxidized pits would do that indeed.
I would buy the Chinese one and derating it.
I still know nothing. Bravo.
I dont buy Chinese stuff design my own circuits are challenging also fun to create a circuit is robust and wont ever fail .
Depends on how good you are in circuit design .
Also those online stuff are so fake and over rated
Example a triac datasheet shows its absolute max rating for a decent factory when you buy a Chinese unknown factory for same
Triac number and do a stress test on it you find it very funny how it fails and blow even when not reaching the max ratings from the original datadheet.
Sorry....not much of a comparison ... doubt if they were made in same place... you kept saying 'mis-labelled', as if it was a 'mistake', it was NO mistake, it is FRAUD plain, and simple. Counterfeit is a strange word, more like marginal design, marginal component quality, and marginal workmanship.... and FALSE specifications.... Remember, you get what you pay for, and MOST of Chineseum components are JUNK.....steer clear.