Solid state relay | SSR

Solid state relays are similar to traditional electromagnetic relays but they have no moving parts and the switching is done via solid state circuitry rather than an electromagnetic coil. This video demonstrates how an SSR (solid state relay) works using a bench power supply unit.

[burnerjack]

SSRs are prone to back EMF damage. When using them to power an inductive load such as a solenoid coil or motor coil, when the power is cut to the coil, the magnetic field collapses. This causes a very high voltage spike of very short duration. This voltage spike will eventually destroy the relay. To overcome this, in a DC circuit, a diode connected in parallel with the coil and ground is installed in a reversed bias orientation. Because it is reversed biased, it is normally not conducting, but when the voltage spike occurs, it will be shunted to ground, shielding the relay from damage. In an AC circuit, sometimes a 'snubber' is installed (r-c ) with a MOV.

[spiritburners]

Well that explained it very well, I always wondered wheter you had to leave the switching voltage on all the time or whether it was just a pulse... Thanks for clearing up that one.

[xngdestini]

your the best thank you I appreciate the videos and information I'm sure your very well trusted in the UK your very knowledgeable on alot of subjects

[AleksandarKospenda]

Those are neat. didnt know those existed. The variable voltage for the activation is great. 

[markdavies]

I am building a brewery at home and use two SSRs wired to the back of two Dual Pid Digital Temperature Controllers, as the controllers can only switch about 3amps. Works great but you have to set the PID controllers up so they have an output cycle time of a couple of seconds or you burn out the SSRs as I am switching 10amps.

[mrtechie]

Electronic control of tankless water heater: Use a PID? SSR vs SCR?
I have an 8KW Atmor tankless water heater that has two switched heating elements. I want to add stable electronic temperature control. But I can't find good information about the different options!
Seems the PID + SSR MAY have longer switching time, and that MAY reduce heating element life from thermal cycling vs a higher speed SCR. But I am having trouble finding the real answer.

[chazphot]

Very informative video as usual, I have a quick question about one of your older videos but thought I'd ask here as you're more likely to see. Regarding the video on Bahco ratchet spanners you mentioned that the bolt/nut cannot pass all the way through and so is held captive making it easier to use. I assume this only works for the larger side of the two, for example a 19mm bolt wouldn't pass through due to the smaller 18mm on the other side but would the 18mm pass through because the other side is larger or is there some sort of plate etc that stops this happening? Thanks in advance, keep up the good work!

[nadeem]

is this must to provide AC volts just for testing at output side? or will it show continuity just with multimeter?

[ultimatehandyman]

@pete r
It could be induced voltage from a nearby circuit. Led's are notorious for this.

[billmoore]

The output specifies 214-480 VAC. Can this SSR be used to 'switch' a DC load ?

[Saim-fdir]

Hello i have a 12v 4amp adapter
I want to turn of and on my water pump motor with ssr relay
So if i give the 12v current to the ssr relay while testing other 2 points continuity i dont get any beeps from multimeter why is that can you tell me what i am doing wrong?

[EnergySeeker]

nice video, what is the max frquency can we use on the input ?

[leeo.alexander]

I have attempted to register but have not received the activation key for the forum. I have 3d printers and one of them has a solid state relay in it and I can get the printer to turn properly with it wired into the system. One of the printers is factory built and have the same basic setup and it works. Not sure what I did wrong, both are wired the same.

[rich]

Worth pointing out that you need to test for continuity in diode test mode for most multimeters.

[justgivemethetruth]

another great thought provoking video.
what do you make from this ?

[africanhistory]

now how do you get the reverse affect? When there is a current it switches off

[Maxsdiscos]

What do you use your bench power supply for, out of interest, are you an electronics geek?

[Mixbag]

i had one of these relays to turn on/off a 240v (UK)  light fitting that had a led bulb. when the relay was i nthe off position the led light would flash on and off. when i turn relay on the light would light up as it should. i cant figure out why the bulb flashes when the relay is off. can anyone help ?

[SFORSANDEEP]

I've got a 40 amps SSR. But it shows no continuity even if there is an input DC voltage given. But when I connect a supply ac voltage of 220v to one terminal I tested the other terminal with a tester tester light blown. Also Multimeter shows 220v from the exit terminal. But no input DC voltage is given. Also the weird part is even Multimeter shows voltage from exit terminal, it. Does not show continuity between those terminals. I didn't understand why. Any idea

[salifdieme]

Hello. your video is very interesting. I would like to know if it is possible to connect the input of the ssr relay to a 12 volt 100w solar panel and to the output of the relay I plug in a 220-240v 1100 watt electric pump. thank you so much.