






⚡ Stay cool, stay powerful — the SSR that means business!
The TWTADE SSR-40 DD is a solid state relay designed for DC to DC switching with a maximum current rating of 40A and input voltage range of 3-32V DC, outputting 5-60V DC. It includes a high-quality heat sink to manage thermal load, ensuring reliable long-term operation in industrial and scientific applications. Certified by CE, RoHS, and UL, this relay offers robust performance and easy installation with screw connectors and surface mount design.


























































| ASIN | B079BGGVYX |
| Batteries Included? | No |
| Batteries Required? | No |
| Best Sellers Rank | #70,489 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #19 in Solid State Relays |
| Brand | TWTADE |
| Coil Voltage | 3 Volts (DC) |
| Connector Type | Screw |
| Contact Current Rating | 40 Amps |
| Contact Type | Normally Open |
| Current Rating | 10 Amps |
| Customer Reviews | 4.1 4.1 out of 5 stars (606) |
| Date First Available | January 25, 2018 |
| Is Discontinued By Manufacturer | No |
| Item Package Quantity | 1 |
| Item Weight | 5.9 ounces |
| Item model number | SSR |
| Manufacturer | TWTADE |
| Material | Copper |
| Maximum Switching Current | 40 Amps |
| Measurement System | Imperial, Metric |
| Minimum Switching Voltage | 3 Volts (DC) |
| Mounting Type | Surface Mount |
| Operation Mode | Automatic |
| Package Dimensions | 6.22 x 4.06 x 2.4 inches |
| Part Number | SSR |
| Size | DC to DC 40A |
| Specification Met | CE, RoHS, UL |
| UPC | 635648190440 |
| Wattage | 32 watts |
S**E
Good relays after a year of use
I have two of these in enclosed but outdoor locations. Working well after over a year.
R**E
So far so good
I'm using two of these to control a 110v 1300watt heating pad that draws around 11amps and a 110v 550watt 5amp 635cfm exhaust fan. I havent ran the heating pad yet, but the fan does great. I have the heatsinks cooled by a 24v fan and 150c thermal fuses fixed to both of them in case they fail. If I ever have any issues, I'll report back with updates. Edit: I guess I should mention I'm triggering them with 24v DC off of a PSU. Low voltage side is negative from the SSR to the negative on the PSU and positive from the PSU to a switch to the SSR. 110v side interrupts the LINE wire for the exhaust fan.
P**D
It works reliably for one year now
I use it in the garage ceiling to control multiple LED light bulbs from the light output of the garage opener. It works reliably for a year now. As one may know, if you use LED bulbs for the garage opener light, it decreases the range of the openers (if they work at all) and in time it will burn the internal wireless controller of the garage door opener. The solid state relay I use it as a 'separator' to route the AC circuit of 3 LED bulbs directly from the 120V house circuit and command it with the garage door opener. I mounted it in the garage ceiling and almost forgot about it. Now my garage openers range from the cars is more than 150 ft.
L**D
I'm so damn mad right now
This relay caused me hours of scratching my head. I am using it in a Tesla and i'm thinking something is wrong with the car. Come to find out that even though the circuit I chose to activate this was working properly, this relay stayed on and allowed the power to go through what is supposed to be open contacts. Instead, the ohm reading is 372k ohms of resistance which is enough to keep the led lights I used to stay on all the damn time. This wiring was all in an enclosed space so it's kind of a pain in the butt to deal with. I ended up tapping off of another circuit and using a standard relay for now just to have things working. I only had it wired for 2 days. The voltage going to it was between 8 and 15 volts dc and the load was probably an amp at 15 v dc. This was well within the range listed.
R**O
Pretty good for the price.
I have about twenty of these built into temperature controller boxes now. They run almost continuously at around 50% duty cycle average for the last year or so. They are switching only about 2A of resistive current (on the 40A rated units) and they stay cool. They have been mostly reliable, but we have had a few fail. The ones that have failed have failed because we connected a shorted heater. A 15A fuse has proven insufficient to protect the SSR from this happening. When they have failed due to a short circuit, they have failed CLOSED, which is bad. This could be a big problem, depending on your application. Please keep this in mind!! Ultimately, the devices are cheap enough to consider an expendable, like a fuse. Just keep in mind that they seem to fail shorted and they are fairly delicate. I personally wouldn't run more than about 10A on the 40A rated ones.
A**R
Good for computer-controlled shutoff of solar (PV) panel input.
We used this to create an additional safety shutoff for a mobile solar power system. Our control circuit measures the battery voltages, and if any are over the tolerance setting, it cuts a small relay that then cuts power to this unit. This unit then faithfully disconnects the solar input, effectively preventing over-charging and increasing overall system safety. Unit has been in use consistently for several months now and has performed reliably. Our load is much smaller than it's rating though (about 10 Amps at ~30 volts), but the unit does not appear to get warm even while handling this.
S**S
Be careful how you hook it up. The ref diagram is WRONG and even says AC when this is a DC-DC SSR
I gave this product 5 stars because it works very well. I am using 12 volts DC for the signal, so it operates very reliably and it works well, switching it on and off frequently over extended periods of time while controlling a load up to 35 amps or so into the inductive load of a 2500 watt ZVS induction heater running at 48 volts. However---- as others have said, the reference diagram is wrong and needs to be changed. Even the INPUT is listed as being AC!!!
J**.
They get very hot
They do what they say, but they get very hot.
H**N
When the thermostat on the freezer would open (break the circuit between live from the wall and the compressor), some electronics would be impacted from the arc inside the termostat. I connected the SSR's switching side to the thermostat and the load between live from the wall and the compressor. No more interference with electronics now.
C**N
Remplacer l'original pour une fraction du prix
M**L
Needed to replace a relay on my espresso maker. The heat shield was just a little big but easily ground down to fit. Has been working perfectly for about three months. Reports of occasional relays melting made me apprehensive but pictures suggest that this occurs at one of the AC terminals. I suspect that the wire at the terminal was not adequately secured. I placed an 'O' terminal on the wire so that I could anchor it securely. Also chose an oversize 40 amp relay (used for the 13 amp heater coil.) Happy so far.
C**N
Fonctionne très bien
R**L
Works as expected
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