I big Mosfet It looks like This was the SSR that heated up in my first test.
SSR testing
- Thread starter Craig
- Start date
offgriddle
"FOREVER BEGINNING"
A USA made SSR, not sure if it's made of pacific rim components, not sure if prices are reasonable, unsure if features and reliability are acceptable but it's not a bad idea to encourage diversity and global sharing of jobs and income instead of, you know, the business as usual sole sourced routine that has become the rule over the past few decades. http://solidstaterelaystore.com/
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Pretty good prices across the board IMO BUT, unfortunately they do not have high amp continuous duty units. 100-300A range is the most common for an RE application, bigger (more amps) for larger installations. Craig is actively hunting & narrowing down the SSR's.
I came across a manufacturer yesterday which makes Energy Saving Continuous Contactor Relays (not SSR) which only use 1.7-1.8W to handle the contactor coil while the default ones offered by Chargery use 4-10W. Different Options for Different Use Cases is always good to have. The ones I found are similar to these https://www.electriccarpartscompany...-12-Volt-900-Volt-with-9-Volt-36-Volt-DC-Coil (seems a tad on the rich side considering these are not SSR. IMO)
offgriddle
"FOREVER BEGINNING"
Thank you for the info..
I'm just curious, with mechanical relays being easily capable of handling the higher amperage and possibly providing a wider variety of switching arrangements, is the main or only reason for going solid state to eliminate the physical contacts which do eventually wear out?
Note: I'm just looking at some SSR's now, the higher powered relays have fan cooling! Than must waste some precious PV current to not only heat up the silicone as the amperage passes through it but then to use even more energy cool the components down with a fan?
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
The contacts last for 100's of thousand of operation IF used within spec, go beyond spec and well, like everything else Poofdah !
The traditional Electro-Mech relays are power pigs... the latch can use many watts per hour. Some are better than others of course and tehre is a huge diff between continuous & intermittent use relays as well.
SSR's typically use around one watt depending on type & design. Consider that with the large aluminium heatsink, the small 100cfm box fans (like those used for computers) use tiny amounts of power and quite insignificant in reality.
Unless we're talking many kA continuous a proper SSR should not need a fan, nor a 1 m² heatsink. More than 10-15 W wasted per 100 A continuous is unacceptable to me and shows bad design and/or too much cost reducing from the manufacturer.
My concern would be the machine screw termination at 200A continuous.
I have thermal paste and I will be trying to rig up enough inverters and resistors to suck out a 200 plus amp load. I have 3 inverters a 2500,1200,and 600 watt all together that will give me 180 Amps at 24 volts if I can find enough things to plug into them. I also have some dc loads to add.
I may be heating the whole neighborhood this afternoon.
I may be heating the whole neighborhood this afternoon.
newbostonconst
Solar Enthusiast
- Joined
- Sep 24, 2019
- Messages
- 1,005
I am with OFFGRIDDLE..... What application are you trying to use a SSR. They have specialized function and are usually used where you need fast and frequent switching. Using them as a standard relay is not a good design.
The problem is this a 10 watt draw 24 hours a day is 240 Watts a day times 7 days is 1680 watts now use 2 relays we are looking at 3400 wats +- . In my location I can go 7 days without measurable sun so I do not wish to have that high of a draw but I still need protection from over and undercharge. This is a remote system I can not be there to switch things on and off.
boondox
Chief Engineer, RedNeckTech Industries
- Joined
- Mar 1, 2020
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- 788
Contacters (relays) capable of switching large amounts of DC current generally need a fair amount of power for the coil. In order to break the contact quickly they have a pretty good spring and of course that spring has to be held back when the contacts are closed. So when power is at a premium the SSR can be a winner. That said, I still wouldn't use an SSR for everything and the cheap ones generally do have a pretty high rsdon which can waste as much power as a coil. If you need to put a fan on it you are probably running it too hard and the added draw of the fan negates at least some of the power savings of an SSR. In truth I would guess that most of the cheaper SSRs are good for about 1/2 of their rating if properly heat-sinked.
This is exactly why I am testing them. The whole purpose of the thread find a good SSR that works as we need with low current draw. And is efficient.
I forgot to mention it earlier but 0.34 A at 12 V seems a lot for a SSR, that's 4.1 W.
Can you try a another voltage like 6 or 9 V to see if it's linear or what?
Any chance you open this one when you're done testing it? because now I'm double curious.
Spoken like a true Engineer! LOL My parents knew I was destined to be an Engineer when the first thing I would do with a new toy is take it apart!
I forgot to mention my clamp meter was off its more like .01A draw at 12 volts. I will set up a shunt to make a more precise test.
Pretty much the same story for me ?
I'm curious to see what mosfet they use to switch 200 V at 240 A with a very low Rdson because the higher Vds they can handle the higher the Rdson and 200 V is pretty high.
Also I'm curious to see why they suck 4 W.
Edit: ah, ok, that seems a lot more reasonable. Do you have a DMM? if yes then just put it in series with the SSR input, it'll be more precise and simpler than shunt, DC clamp, etc...
I will try and open one up if I get more. Don't want to ruin the good ones yet
