Teardown of an eBay 25A Solid State Relay. (SSR)
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- Опубліковано 5 жов 2015
- You can now buy me cake and things to take apart at:- / bigclive
A solid state relay is an industrial component used for interfacing low voltage control signals to high current mains voltage loads.
They sell them on eBay at a ridiculously low price, so it's time to see what's actually inside one of these eBay units. - Наука та технологія
Thanks Clive! I change out CryDom HD4890 SSR (480Volt 90Amp) Solid State Relays that run 7K watt heater bands on a PVC extrusion lines on a pretty regular basis. About 30 of them are used per line to heat "zones" controlled by Telemachique controllers. Always wanted to see inside one but the Crydom's are potted! Great video! Hate that the Crydom's sometimes fail in a closed gate state and burn up heater bands!
The shorted failure is a common semiconductor failure mode, particularly in the event of the load short circuiting. It's a good idea to way over-rate the solid state relays and make sure they are mounted on proper heatsinks with extra cooling if needed to make them survive longer. Another good idea is to consider a generously rated high temperature thermal fuse inline with the heating elements to kill the power to them if they start running too hot.
Bought a few "FOTEK" SSR-25DA a few years ago, used them to control approx. 1kW heaters at 230V. A very light load, only 4-5amps and I have had no problems. Fortunately they are also mounted on a decent heatsink, enclosed in a metal box and controlled by a PLC so there is no human contact with the input.
Had some leftovers so after watching this video I cut one open and found a single BTA20-600 inside. A bit bigger than the one in the video but still only rated for 20A, not the full 25A.
The input circuit is different and actually quite nice, it has a LM337 regulator connected as 12mA current limiter, which supplies constant current to the optocoupler for the full range of 3-30V.
However the PCB is horribly badly designed, input and output traces very close (1-2mm) for the whole width of the board, there is quite enough space to do this properly, really makes one wonder why they had to screw it up.
After some thought I got more curious and two weeks ago I ordered a few more SSR-25DA and SSR-40DA from different China ebay sellers just to check them out. Shipping was unusually quick, they all arrived here in Iceland 7-10 days after ordering.
First I noticed that none of the items looked exactly like the pictures in the listings, minor difference like "Taiwan made" changed to "Made in Taiwan" and "Solid State Relay" becomes "Solid State Module".
Next I split them open and found a single BTA12-600 inside the SSR-25DA type as in the video. So only a 12A TRIAC in a 25A rated module, not good!
The listing pictures for the 40A show a module with two screws on the bottom, indicating it might have two power-components, one could even dream about two antiparallel SCRs which is the proper way to make a 40A SSR.
Unfortunately they sent a different type with just one screw and a single BTA16-600 in the SSR-40DA. 16A instead of 40A, even worse than the 25A one!!
Also the RC filter across the TRIAC was completely missing, no components, just empty holes on the PCB!!!
The PCB of the 25A type is exactly like the one in the video, but the 40A has a much better PCB, with SMD components, good clearance and a milled slots between input/output traces. The 40A is also filled with more resin, the space below the PCB was almost completely filled on the output side and the components on top of the board well covered. A real shame they then ruined the whole thing with a 16A TRIAC.
Some used heat conducting paste when mounting the TRIACs, some had no paste.
It is possible to disassemble those SSRs without much damage, first pry the top cover with sticker up using a small screwdriver. Next use a fine tipped soldering iron to melt/burn the resin from the head of the TRIAC-fixing screw. Then remove the screw and finally the metal heatsink. The TRIAC will stay in place and hopefully not tear any traces on the PCB.
Reassembly is also possible, but hardly recommended.
After this experience I will try to avoid those SSRs.
They are only good for appox. 25-30% of rated load.
They should not be used where humans (or any other live creatures) might come in contact with the input wires, the insulation between input/output is not to be trusted.
i got one too, im using it with a PID temperature controller and a 2kW water heater. works fine, i dont have heatsink mounted. few minutes of use and it was slightly warm.
No problems with them at 6 amps or so. Varistor protection and additional RC snubber is highly recommended.
Thanks for this tear down Clive.
I have the exact same part from an ebay seller that I intended to use in a Kiln controller (~3KW max output).
So after watching this I stripped mine down to reveal that it also contains the BTA12-600B, obviosuly not quite sufficient for my application.
I have now ordered a BTA24-600B to uprate this to its original spec of 25A, at least I will now be operating its safe area.
Thanks again for your entertaining and interesting videos!
I have a few of those in my shop. Thanks for the helpful teardown.
+Applied Science Well, you wer`nt to know were you. Hope you sell them and make a profit at the end of the day.
He is tearing down a fake one, just saying.
+Bradman175 With as many fakes as real ones: How can you tell?
+Adam Perry Very easy.
ul.com/newsroom/publicnotices/ul-warns-of-solid-state-relay-with-counterfeit-ul-recognition-mark-release-13pn-52/
Anything that doesn't match the image of the legit one is fake. The one shown in this video is missing the maximum amperage rating.
+Adam Perry and holy crap how scary it is that most of these fotek ssr are fake!! They're meant to cost like $40!
I have considered these relays but avoided them because of safety concerns. I have no problem piling on heaps of dubious low-voltage components that are practically free, but it is a different situation when a component is to be connected to the mains. I don't want to burn down the house or electrocute someone. Even though yours seems reasonably good, I think I'll pass. When certification markings are false and no one is accountable, it is hard to have confidence in a part.
This is the first video of yours that I've watched Mr. Clive, and it is simply fabulous. First class. Thanks for doing this.
+pillsnotbills I agree with you. Something that fails with no disastrous consequences is sometimes worth the risk. If I fitted one of those SSR's to some kiln or printing press and then it set fire to the factory, well I'd be to blame. £15 will get you a proper american or european approved unit, so it's not even worth the risk.
www.rapidonline.com/kudom-ksi240d25-l-panel-mount-ssr-4-32vdc-48-280vac-25a-load-with-led-zero-cross-60-1579
Wow! Thanks for such a quick response. I am pretty much still in the electro-mechanical era so this type of thing is new to me, but still interesting.Pity most schools can't make subjects as interesting as you do.Fantastic work!
Stumbled across this whilst going through your older videos - and I just happen to have one of these sat on my desk! Very useful teardown and glad to see they aren't all that bad.
I took apart an old 1980's vintage USA made 10Amp 140V ssr and it is indeed fully filled with dense black compound. The lid is a full cover and they have little legs that extend into the potting compound to hold the lid on. Much more robust construcutib than what is shown above.
Thank you! You've been very helpful.
I've been eyeing some of those for a project. Every time I hovered over the checkout button I would get a little voice telling me, "You get what you pay for."
Always nice to see what you're really getting in these modules.
SSRs are really intended for fast switching that would wear out a contactor (controlling temperature on a heater, switching in a VFD) If you want something to be left on for long periods your usually better off with just a contactor. Best for resistive loads, they don't handle inductive surges well.
Years ago we used to build home control boards and in one of them we used a similar arrangement but simpler as the input voltage was known - hence resistor into the zero-crossing opto-triac then the same components on the right. We used 15A triacs on heatsinks and controlled 2KW heaters no problem.
I messed around with some triac circuits some years ago which were basically schematic equivalent to this thing. Had no difficulties powering incandescent lights, occasionally some difficulties with compact fluorescents (the holding current you mentioned).
One thing that I think would be extremely good advice is to be VERY CAREFUL about powering heavy loads and/or heater loads with these devices. When the triacs got warm, they tended to self trigger, so that even when the opto-isolator circuit was turned off, they would still pass current. (negative temperature coefficient of solid-state devices)
If you are thinking of controlling a heating device with one of these, I strongly recommend using an electromagnetic relay instead -- especially given clive's teardown results showing you can't trust the printed current rating.
Or, yanno, you could use a proper SSR instead of a fake one. Real SSRs are not built this way, and they use back to back SCRs not triacs, so there's fewer junctions in the current path, the heat sink plate isn't a joke, the cases are backfilled properly, and so on. You do realize that you CAN'T use a mechanical relay for PID controled systems, right? You knew that, right? RIght?
Well done Clive. Good investigation.
Thanks for posting, it's good to see the insides. I used an SS40DD (to switch a DC 3A load) controlled by an arduino GPIO pin. I was using it well within spec, but it got very hot indeed and all the case melted and twisted. I built my own after that :) :)
Thanks for that...I haven't used triacs in my ex-line of work so would not know but I do know now. I will be on the look out if I ever do.
Have used 25 amp solid state relays but when load was more then 3 amps would mount it on a heat sink and use heat conducting paste. Have just used a 6 by 6" aluminum plate that was 1/4" thick for loads up to 50% of label. Nice vid.
Just got one of these to control the heated bed on a 3d printer I'm building. It was a relief to hear your verdict that it may be up to the job. Fingers crossed.
It's fascinating to see what I've been using for the last six years! I'm glad now that I acted on impulse and used them conservatively, and only for personal projects. But they have worked without complaint.
It is always interesting when you take things to bits. More spacing! More potting compound! Ya, for limited usage, looks OK.
This is one I needed to see, but I didn't know that till I saw it. This is amazing to see the insides of something I have used so many of!
Thanks for warning us about this kind of devices !
I tested mine today, the led lights up, but it doesn't work at all.
Always wondered what was in them, thanks for the teardown.
Hi Clive. I really like your video's. keep up the good work! greetings from The Netherlands
Outstanding equipment review! Thanks.
I use this one for my brewing temprature controller. It works well in that application with a 12v signal from a PID to trigger it. If I was to market the unit I would probably use better relays and pid's though.
OMRON tops there SSRs all the way with sealant. Very seldom have any problems with their components, but they are quite pricey.
While to great in design for general use this looks quite decent.
I've always been afraid of buying these on Ebay but I think I'll grab a couple now for personal projects.
I did not expect even that quality for that price.
I cant get my head around the concept of faking a 25A SSR and selling it for a couple of pounds on ebay when they could sell it for the same price rated and labelled as an 8A device instead. It would still be a very competitive price but legitimately rated.
as far as i know they all agree this fakery, yes, competition kicks in and they have ridiculous prices but... i saw that 60% of what they sell is just fake, fake chips, fake transistors, only modules work ok, because 99% of who buys this stuff can't tell the difference and a chunky transistor will turn on a small motor even if there's a 1\2 current transistor actually inside, novices are happy, modules work... i'm not è_é... i couldn't find a BC639 or compatible except on super expensive stores outsice the china cheap (just as en example, don't buy op amps eighter)... yes instead of 1€ i'd like to spend 1.5€ for a bag of 100 of those transistors but LEGIT ones, not caring of branded ones much
Welcome to China - Manufacturing philosophy: why waste money using unnecessary resin... you get what you pay for, but this is dangerous and a fire risk
It’s Chinese.
In general, it seems like the Chinese tend to prioritize things working and being cheap over reliability. So if they give you a current rating, that's not going to be a guarantee of steady-state functionality at that load, it's going to be "this will probably work for all these applications"
@Alweg Fan , as a long time engineer working for a company that supplies industrial automation system to Chinese heavy industries, including power generation, practically everything is sourced either out of the USA, Europe or Japan. I go over to a plant and I am rubbing elbows with representatives/engineers from Germany, Japan and the States primarily. I don't see ANY Chinese sourced parts/assemblies in those critical industries. So I think the top guys who are in charge of critical industries have a good handle on the quality and reliability of their own lesser industries. Now I suppose that over time, this is gradually changing, and more in some industries that in others.
I'm using a pair of DC-type SSRs to control the electromechanical spring brakes on a 12.8m satellite dish (former NATO, we're restoring it for scientific use). The control system is 24VDC, as are the brakes, but the brakes are higher current than the controller can sink, so, SSRs. They're notionally rated for 40A, but I'm guessing the truth is much less. They came with heatsinks and the brakes are only putting a roughly 4-5AMP load through the relay output--rather more than the controller can directly sink. I've been an electronics tinkerer since 1973, and this is my first experience with SSRs. I also picked up some 24V contactors, in case the SSRs didn't work out, but, so far, they're fine. I placed large (30A) diodes across the brake coils, because it wasn't clear whether there was any kind of snubber network inside the SSR.
Brilliant! I've been concerned about this unit that I bought recently, it's for a 240v floodlight being connected to my 12v alarm, you've showed it's properties well. Thanks! Subscribed!
This is incredibly useful information. Thank you very much!!
Great stuff,i would like to see inside a proper non clonned one,just for reference.Cheers Clive,love your vids.
Christ... I had one of these explode on me today, an SSR-40 DA unit rated to 40A. Opened it up to find the same bloody triac as the one in the video!
PodeCoet lmao, that sucks dude
PodeCoet thats insane? what is with the dopey chinese engineers that approve of this? After watching dozens of clive's vids, you get the idea they arent taught to actually understand electronics.
Hint: It's not the engineers, it's the marketing people...
Just received my second batch of these for some small arduino projects. They've all withstood a couple of months of switching 5A every few seconds. Very happy with them. Obviously not a fully Professional part though.
Just to expose my ignorance (and laziness) can I ask if you think these could comfortably switch an inductive load such as a large roller door? In my distance experience working on automation electronics I do recall having to replace relays with alarming frequency because their points had vaporised - or worse welded themselves together. These look like a good alternative?
+The Backoffice Sort of. The contact welding you've described will probably destroy a triac/SSR. You'll need to "snub" any voltage spikes (those are present when switching any inductive load). A combination of resistive and capacitive snubber across MT1 and MT2 with the addition of a MOV, gas discharge tube, or another type of high voltage device to clamp any spikes would be needed. Adding those snubber devices to a regular mechanical relay will probably save the relay and you wouldn't need to fix the problem with an SSR.
+Jammit Timmaj thanks for the info and pointing me in the right direction, I will investigate along these lines!
thank you so much for this video
i keep learning more and more from you
keep up the good work sir
I let the smoke out of one of these, yesterday. On a temp. Controller, for my homebrew. It worked fine for the first 20' or so. Then that cooking component smell, it failed open.
Thank you for sacrificing this relay to show us how it works. I am concerned that when there is 240V AC on the relay it is showing about 10V AC between the backplate and ground or neutral. I wanted to bolt this to a grounded chassis but with a potential between them it sounds like a bad idea.
'with a little bit more design effort' a true saying for most bargain Chinese products!
There are a few that are exceptional. They seem to have two levels of experience - highly skilled and rookie with nothing in between.
You can sit here ranting nonsense, but you have never created a product in your life. BTW the gap there is around 5mm which would require a voltage of 15000v to jump across that. There is no design flaw here, only a flaw in your thinking.
Who?
in theory and ideal conditions that's the isolation ( remember, if it ever did cross over that would be VERY VERY bad ; it would go straight to a likely low voltage control network) ... and like clive said there is literally no reason they made it so much less then it could have been.
There is a lot to be said for truth in advertising, or at least truth in specs. No matter what your skill level, there is no excuse for lies like a 12A triac in a device that claims the ability to switch 25A.
Bro....... I want to drive one of these from 230 volts AC, means switching voltage should be 230v input and 230v switched output. ........
Could you please provide me a circuit to drive it from 230 volts AC.
A diode, a resistor, and a capacitor. Or just wire in a small 5 or 12v power supply.
I love how you have teardown videos of the random stuff I buy from ebay.
It is interesting to see how one of those commercial modules does it. I don't know about pulling multiple amperes through it with only that bottom plate for heatsinking, though I guess that depends on what you have it mounted to. And I'm assuming that the tab on that triac is isolated? I have a bunch of 4A/400V triacs on hand and plans to build one or more of these. I suspect that I'd probably use somewhat different parts for the snubber network, though. I plan to use the MOC3010 opto, I think it's the MOC3020 that's the one with the zero-crossing detector in it. Been a while since I looked at those datasheets.
Thanks for showing BTA
I prefer the Use of Crydom SSR's. I have a bunch of Crydom SMR 4850-6 which can handle 96-480VAC at 50Amps. To control these thing you need a Supply Voltage (8-32VDC) to power the internal Logic, and then you can use the inverting or non-inverting control input to turn this thing on and off. It also has a N.O. and N.C. Alarm output and a integrated red Alarm Status LED to show abnormal conditions. A green LED shows normal operation when switched on. The Encapsulation is made with thermally conductive Epoxy.
Wow. I’m glad I went with the 40 amp version for a heating application recently, Same brand. bought from amazon.
GreatScott also did a review of a 40A version of these, which also turned out to have a 12A rated triac inside. So maybe we should consider them all as 12A SSRs regardless of their marked amperage... at least until we have destructively dissected one to confirm a higher rating of its components.
Ben Hetland I’m wondering it it’s rated 12a with no heat sink. But maybe with a heat sink it can handle more amperage
I just bought one of these. After watching this I stated wondering if I fill it with resin it might be better than it is now. The load that it needs to handle would be around 8 amps so it should handle that well.
After watching this video earlier this week, we had a system come in from a university that had one of the counterfeit SSRs, Luckily it hasn't been run at all.
Thanks for doing this video, I have used this in my arduino controlled espresso machine, I didn't pop it (rare for me!) I figured it would be encapsulated, there are a few brands on the bay, identical except the red 'fotek' brand. Price was the same, so I went with the Fotek, although mine is also lightweight and airy and I also expected it to be potted full. Learned a little and a lot here today, I am running mine at 5v switching and only using it for a 1300w-ish heater under supervision so for me I am sure it will be fine. Great video!
I believe one can never have enough Arduino controlled espressomachines.
Thanks 😄
And who is supervising ? Not another Arduino ,I mean why an Arduino in the first place then ,of have you totally hacked your espressomachine ?
,
I have several of these that I use around the house, never had an issue driving just a few amps..
I was wiring one of these up at work today and this video showed up in my feed when i got home. How odd. It's only switching 3 Amps but controlling a rather critical temperature.
Thinking tomorrow i'll change it for one of the £25 ones from R.S.
I bought a couple of these several years ago for a brew fermentation controller (BrewPi). Hooked it up to my old fridge and when the fridge should have turned on I heard the sound of something from the compressor but it didn't start up. I assumed the compressor must have seized up after being idle for months so gave it a few whacks with a rubber hammer but still the same,
Something then made me think to check the SSR and turned out it had a crazy on resistance so when hooked to the fridge, the output was something like under 100V rather than 220ish. Swapped it out for the other SSR I had and it worked fine... Invested in regular relays for that project instead.
I do understand there are no shortage of fake FOTEK SSRs that likely you and I found for bargain basement prices, but the genuine FOTEKs are more reliable. What about ordering one from CPC or the like and seeing if that's any different?
Two RC constants in the circuity is using two time constants or double time constants is to make full use of the triac for more efficacy. Thus making use of the negative and positive parts of the sine wave
Today my 40a fotek ssr burnt out after a good few years of switch a 2kw heater so I decide to lake a look, the triac was a bta24-600b rated for 25A. Thought I would share as this may be useful in relation to Clive's video.
i use these in pinball machines that have ac motors controlling backbox animations
they are easy to drive off the 24v solenoid lines and don't have woefully undersized traces on pcbs to burn up without blowing an 8A fuse
I had trouble driving one of these cheap ones with a raspberry pi (3.3V). Had to add an opto isolator. Works well though.
Thanks Clive. Have the 40a version switching my home theatre as the 10a relay kept welding shut!
Make sure it's in an area that is fire-safe. These cloned SSRs are not rated anywhere near their stated rating.
@@bigclivedotcom If it's really only 10a with a heatsink, load should only be about 6a by my calculations.
Watching this was interesting I just replaced one on my T-shirt heat press, fully repaired for a few pounds.
We actually use similar relays. Allen bradley drives switch it to power a 120 volt brake on sew eurodrive motor. Works great. Great video as usual Big Clive ⚡️🏴⚡️
Our relays are allen bradley or omron.
"Our relays are allen bradley or omron." -- which means they aren't built like this trash at all, that's why they work fine. People in comments seem to think this video is an indictment of solid state relays, when it isn't - it's an indictment of FAKE CHINESE "solid state relays", built completely different on the inside from the real thing.
@@railgap You are right allen bradley solid state relays we use have 100% reliability. So far 26 years and I have never seen one fail.
Nice explanation man, tnx for all of the info.
if you use one of these make sure you derate it by 50% especially if you don't use a heat sink. (ebay sells them) I have had quite a few fry spectacularly (fire smoke total met down) controlling a 1500 watt heater 120 v. swapped out for 40A rated ones (almost same price) and stopped the fire hazard. BTW they work very well connected to output pins on arduino boards
great work Clive next time fotek ssr-va. I really like your work best videos here. love your short video format keep it up.
I've recently subscribed. I've been trying to watch all your videos to get caught up. nice channel...
I have bought 4 of these. one of the first two would not operate at all. I've had no issues with the other three.
I have two operating in my cnc setup, switching on my spindle and vacuum system with no issues at all.
My little spindle pulls maybe 8 amps, and my vacuum about the same.
Great tear-down, really interesting!
I've been using one of these Fotek branded SSR 25 DA (not sure if the one I have is genuine or fake) for about 1.5+ years to switch a 1.3kW purely resistive load at 240V AC from a 3.3V input. It was ridiculously cheap on ebay, so I guess mine is the fake one. Probably still working because I'm well within the "safe" operating envelope. Would no doubt have exploded by now if I was on 110V mains :-)
+James Ward For a modest load like that it should actually be fine. I guess these are probably widely used in real-life Chinese factory equipment.
We used a 75A SSR in a safety analyzer (bit like a PAT tester). It needed to switch 20A inductive loads and pop a 20A fuse on fault without popping itself. So ... yeah - do it right. If you've spent $4000 on a big brand safety analyzer, it had better "bounce" and not break when you abuse it a little.
Very useful information, my friend uses these...
Only just come across this, and I imagine that at time of watching (Dec 2023) any SS relay on eBay priced at under £5,- isn't even going to have a 10A TRIAC in it. 100mA or even 1A perhaps (Whatever will just about withstand a 30s inbound test on a 20A load) but definitely not 10A! 📦💸😉
That aside; Living in an all-electric flat I'm struggling a lot with cost of heating and I keep considering ideas like running TRIACs and ICs close to their upper tolerances and benefitting from the heat this will give off as a biproduct. Even if I have to swap in new TRIACs every week it's probably still going to work out a lot cheaper than running my 3kW convection heater at the present 36p/kWh for a few hours each day! ⚡🔥💡
This is niftiness incarnate. I've been looking for a thing like that for a while now.
Just bought a different make, similar spec on the outside. Might just tear it down to check what’s in it before using.
I don't know what is the norm, but I tore open a US brand SSR once, and it was basically a chip and wire hybrid, bonded to the copper base plate. No PCB, no packaged components, just chips, bus wires, covered with clear silicone. The circuit was stupid simple, too, like 3 chips and no passives.
I love your videos, big guy (I am a big guy, also). This one in particular is motivating. I have long wondered why solid state relays rated at 25 amps do not perform as advertised. After a really looooooong research, I found that the amperage rating is bullshit. It is all about the wattage. At 5 volts, sure the relay will switch 25 amps, but at 280 volts, it will only switch 1 amp. So, people that want to switch mains power (120 v in the US) are tricked into thinking that they can switch 25 amps, when they can only switch about 300 watts (2.5 amps)
awesome. that makes sense. im gonna remember that
Great tut eye opener
Love your channel.
IIRC real ssrs have the die on the back and everything wirebonded and then there are the mosfet based ones, which are also mounted on the back but they use back to back mosfets instead.
Real ones have about the same inside, but better clearance and filled generally with a glass bead filled resin to save the cost of the expensive resin. This one is filled with a powder filled resin ( probably chalk powder or some milled dry clay) so keep it dry, it probably is hygroscopic.
The 2n ceramic snubber is probably the same 10n 2kV Class Y ceramic used in SMPS use, where it has quite a good pulse handling and also will fail open circuit. Not a bad choice, cheap but will do the job better than a film unit.
Anyway, standard appnote, and the zener does double duty as reverse polarity protection for the opto, though the LED indicator will die with reverse voltage, but who will ever see the red inside a cabinet in any case. As to the triac, I doubt it has any compound, relying instead on the resin seeping under to fill gaps from the screw bending the tab, and if the screw is loose it will keep it in place as well. Isolated tab, so not really meant for more than 5A of load, unless you really use a decent heatsink, which that zincalume casting is not. Rating 220VAC 2.5A with a peak of 5A is more appropriate for it.
I have several of those SSR. You need 5V to switch them on; 3.3V doesn't gonna make it. I made my first SSR with the same components before buying them and have it working for more than a year in a Sous Vide (1 KW heater), so, component wise, them seems reliable to me.
Awesome video
thank you for reverse engineering and the nice schematic (which I copied) for future reference. great engineering work!
Merry Christmas Clive! Would a zero crossing SSR make my well pump easier on my inverter? Not as much as a soft start. But wouldn't it help the start-up inrush current? It's a 120v pump. And not the lower current as the 220-240 version. Being offgrid i run the pump from the inverter or generator. And inverters are expensive. I want to be as easy on it as I can. Or is it worth it?
As somebody who has torn apart high quality solid state relays... Yes, they are typically fully potted basically to the brim.
Thanks clive :-D, i sort of expected it to be more heavy duty inside, that ssr looks more like on par with a lamp dimmer.
I had something like that in a draw, it had a thick base and solid like a block of resin, its a black device apparently made in america, never found a use for it.
I have seen 100 AMP 60 volt DC SSRs on eBay I highly doubt they can sink 100 AMP heat dissipation in the same form factor package that you have FOTEC without liquid cooling. My interest in the DC SSRs was for a golf cart speed controller. The limit however is the PWM response. Others have said the max PWM response was 800 to 900 cps. Krydon brand SSRs are better and can have a slightly higher PWM from 1000-1200 cps but still is within audible hearing range. I would like to see you test and tear down a 100 Amp DC SSR. Thanks for the video.
Opened up an eBay Fotek SSR-40 VA (phase angle controller) you'll never guess what! It's (the triac) not rated for 40A but 25A. At the price it's worth buying two to tare one apart before using the other.
I would advise a PSR-25 if you are looking for something a little more tried and tested for phase angle control.
Good video. Anyway to get rid of the lights flickering when using these for PID control?
Zero crossing is not great for inductive loads. I've used these FOTEK relays quite a bit, however I generally use them @ 1/10 spec. Doing that I have never had any trouble and they are cheap enough that such over-specing is very affordable.
I used one on my off grid solar set up to turn the immersion heater on when the batteries were full.
It's a good idea to have a secondary thermal protection with SSRs as they tend to fail short circuit and jam a load on.
iv had a few of these off ebay, the white ones last for about 5 minutes
the black ones r more expensive but they last and are the ones to get :)
Purchased a few of these not so long ago. Didn't take them up the the marked ratings. Guess I won't be now. LOL I had intended on using one to switch a MOT (MircroWaveOvenTransformer) Spot Welder. I'm quite sure it would had pulled more then 10A. May have worked for some time. Would only be on for microseconds at a shot.
So if i understand this correctly these relays would as you say be used to switch power on and off on say a AC single phase or AC 3 phase big foxtrot motor/pumps etc and then that would mean that the other side of the relay could use a much smaller dc or even ac voltage, switch and wires negating the need for big Foxtrot cables, wires running through to the switch and cabinets etc. Great idea really, I guess you just leave the switch in the on position until you want to turn it off, way safer way to handle all the switches inside cabinets on low voltages and smaller cabling... always wondered how they worked Thanks Clive...
Another very informative video from BigClive, thanks. I have a particular problem in implementing the use of two of these relays inside my CNC electronics enclosure and I wondered if you could you shed any light on this.
As I mentioned earlier, one of these relays switches the power to my VFD, and the other switches the power to my dust extraction unit. They both perform flawlessly as you would expect by switching on and of using a DC control signal. The problem I have is this, I wanted to install indicator lamps into the door of my electronics enclosure, the sort of lamps typically used in industrial control applications, they are actually LED lamps which require an AC voltage to drive them. However when connecting the lamps to the output of the SSR's they are permanently illuminated even when there is no DC signal switching on the relay. Upon checking the relays with my multimeter there is 33 volts AC on the output when not switched, which is enough to illuminate the lamps. Since I have already drilled two 22mm holes in the door of my nice new enclosure I am going to find a work around, so I have ordered two din rail mounted electro-mechanical relays, also from China.
Is this bleed voltage typical in SSR'S, or are these particular ones from China badly designed? Could this perhaps be the subject of another investigative video from your good self? Or is the answer obvious to someone with more than a basic knowledge of electronics such as myself?
One again thanks for your effort in producing and sharing these amazing videos.
+Fred Morris This is common with triac based switching as there is a snubber network across the triac to recue the risk of false triggering by transients. It typically consists of a 100nF capacitor in series with a 100 ohm resistor, and it leaks a small amount of AC current that is usually no problem with high loads, but will cause low loads to at least partially operate.
That would be very useful for capacitive loads as long as they are not too large. EG a switch mode PSU.
The Crydom unit is fully packed with resin and with an admixture of whst appear to be very fine fibres.The unit failed quite expressively by blowing out part of the top on the a.c. side. Looks as if it may have been the resistor -capacitor network. Another blow out on the upper rh side looking at the unit from above.Further dissection looks like it will destroy any components left.
I ordered one of the "40A" ones. Not sure what I am going to test it with or use it for yet though.
jumping back 7 yrs in time now. im guessing the yt algo chose this due to the words resin used so many times so that would be a logical grouping as well as triac which would then bump up the relevance.
Hi Clive, How about taking a look at a STC 1000? They are generally rated at 10a per switch, but heard some feedback that some are popping, failing, maybe not 10A?
tHANKS U SAVED ME A LOT OF MONEY AND WASTED LABOR
nicely and easily eplaned tks
solid video