Relay ratings - Page 1
Forum section: electronics / beginners

author: Lafeu
author_rank: Newbie
timestamp: June 28, 2022, 06:05:15 pm
content: Got my self a nec tokin soild state relay EE2-3NUHLooking at the data sheet it is rated for 220 volts dc and 250 volts ac.Unless i have miss read the data sheet. Would using it with an Arduino to switch 12v cause any issues?

author: D. Head
author_rank: Contributor
timestamp: June 28, 2022, 06:45:01 pm
content: To me this does not look like an solid state relay.Is it this datasheet?https://nl.mouser.com/datasheet/2/212/1/KEM_R7002_EC2_EE2-1104574.pdfIf yes, you can apply 12v:Minimum Contact Ratings: 10 mVDC, 10 μA* 1

author: andy3055
author_rank: Super Contributor
timestamp: June 28, 2022, 06:52:43 pm
content: https://www.digikey.com/en/products/detail/kemet/EE2-3NUH/5502029If it is this, it is not a solid state relay but a standard DPDT coil operated relay with a coil voltage of just 3 volts DC. Contacts can handle 2 amps at 250 volts AC or 220 volts DC. You can use it to switch 12 volts within the current limits above.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 29, 2022, 10:15:10 am
content: That EE2-3NUH is a regular electromechanical relay. Solid state relays are a different animal.https://www.mouser.co.uk/c/electromechanical/relays-contactors-solenoids/solid-state-relays-ssr/solid-state-relays-pcb-mount/?q=solid%20state%20relay

author: tepalia02
author_rank: Regular Contributor
timestamp: June 29, 2022, 11:19:12 am
content: Yes you can switch this relay with Arduino.https://content.kemet.com/datasheets/KEM_R7002_EC2_EE2.pdf

author: BeBuLamar
author_rank: Super Contributor
timestamp: June 29, 2022, 11:25:48 am
content: It's sure is an electromechanical relay. A solid state relay is rated either in AC or DC but not both.

author: Zero999
author_rank: Super Contributor
timestamp: June 29, 2022, 11:33:37 am
content: Quote from: BeBuLamar on June 29, 2022, 11:25:48 amYes, that's true.QuoteNot true. There are solid state relays which can switch either AC or DC.

author: TomKatt
author_rank: Frequent Contributor
timestamp: June 29, 2022, 12:14:11 pm
content: Some SSR's have minimum operating voltages - trap for youngsters.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 29, 2022, 12:56:39 pm
content: SSRs are full of traps, and even if seemingly simple on surface, require quite some understanding. Most importantly, minimum voltage, more strict maximum voltage with little margin against line transient voltages, minimum load current which can be surprisingly high, minimum power factor requirement, large leakage current, and so on.But thankfully, this is an electromechanical relay. Which is free of the mentioned issues, but comes with completely different set of traps: large enough coil current that you usually need some kind of driver, inductive nature so need freewheeling circuit, limited number of cycles, even more reduced number of cycles due to severe arcing if you use freewheeling diode instead of a better solution (I recommend bidirectional TVS), EMI generation, again minimum load current which is often unspecified - contacts requiresomeamount of arcing to stay clean. And so on.In the end, this does not matter too much if you are just playing around and not designing a robust product. I would drive this directly off the AVR IO pin, even though the nominal coil current (47mA) would exceed the pin rating, but it's fun to live on the edge; or, I would parallel two IO pins and make sure to always switch them together in software. Although, if the AVR is powered from 5V and not 3.3V, then you should be looking at EE2-5NUH instead - nominal coil current of 28mA is under the maximum rated pin current. And, the complementary IO structure provides freewheeling. Try it.

author: BeBuLamar
author_rank: Super Contributor
timestamp: June 29, 2022, 02:17:53 pm
content: Quote from: Zero999 on June 29, 2022, 11:33:37 amI haven't seen one.

author: BeBuLamar
author_rank: Super Contributor
timestamp: June 29, 2022, 02:20:19 pm
content: Quote from: Siwastaja on June 29, 2022, 12:56:39 pmYes the SSR is good mainly for application when you need to swith on/off frequently.

author: Zero999
author_rank: Super Contributor
timestamp: June 29, 2022, 02:40:52 pm
content: Quote from: BeBuLamar on June 29, 2022, 02:17:53 pmThey are common.https://docs.rs-online.com/225a/0900766b80db8949.pdfhttps://www.tme.eu/Document/5d1ecce2fb5204350e1e7c0b3733fed6/pvg612.pdfhttps://www.mouser.co.uk/datasheet/2/427/lh1540aa-1767416.pdf

author: floobydust
author_rank: Super Contributor
timestamp: June 29, 2022, 06:39:08 pm
content: OP note "using it with an Arduino" means you still need a driver transistor and back-EMF diode for the relay coil. EE2-3NUH coil is rated 3V 64.3Ω so it would need 47mA which is far too much for an MCU output pin. A solid-state relay requires much less drive, typically the same current as an LED which can be driven by an MCU pin.In production I find that relay package is not great, it does not solder well in reflow, hard to get good heat to the pins. Impossible to remove as well.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 29, 2022, 07:14:40 pm
content: Quote from: BeBuLamar on June 29, 2022, 02:17:53 pmPhoto-MOSFETs. Very handy, good for AC, DC, very small leakage current, no stupid minimum load requirements. The only downside compared to TRIAC types is, they have lower current * voltage ratings and are more expensive, so for "real" mains loads, you would still use TRIAC SSRs.