Teardown of an eBay 25A Solid State Relay. (SSR)
Why Electrical Engineering Stack Exchange recommends it
Electronics Stack Exchange answerers link it as evidence that cheap Fotek SSRs are often counterfeit and cannot be trusted at their labelled current rating.
Recommended by 1 people across 1 different months, 2017 to 2024.
What it is
Big Clive takes apart a cheap eBay 25A solid state relay (a Fotek-style SSR-25 DA) and shows what is actually inside. He examines the triac, its rating and the internal construction, and compares them with the labelled specs.
What people said
Recommends user83628 · 2017-04 · Electrical Engineering Stack Exchange · on “Will this AC-AC SSR work for a safety start / stop switch for a power tool”
Watch this very informative teardown of a Fotek SSR-25 DA (counterfeit?) at [this video] While its triac is rated 12A (not 25A), its look acceptable if you keep current low.
Cites weildish · 2018-03 · Electrical Engineering Stack Exchange · on “Effects of rapidly pulsing DC inductive load on solid state relays”
I'd like to use some solid state relays to turn on and off a high voltage, low current DC inductive circuit ( 120-150VDC, 20-60ma ). The SSR would only be switched on and off at a maximum of once every few minutes-- it would not be used for signaling. - (EDIT: Details about the SSR added below) The specific SSR itself is a Fotek SSR-25 DD-- the DC 25A model sold here [LINK] , rated between 5-220VDC and up to 25 amps. It's definitely a counterfeit, however, so it can only be trusted at up to around 10 amps according to my research (AC counterfeit versions were reviewed well here [LINK] and here [this video] ; I'd expect the DC version to have similar results, but I haven't found reviews for the DC
Cites Transistor · 2019-05 · Electrical Engineering Stack Exchange · on “PWM 1Hz on solid state relay”
Would it create more wear and heat on the solid state relay, or should I do manual pwm over say 10 seconds? No. The SSR switches on every mains half-cycle anyway. For this type of application a zero-cross SSR is a good idea to reduce mains interference. [LINK] Figure 1. Adjusting duty cycle using a zero-cross SSR. Source: LEDnique [LINK] . For further reading see my answers to: Using AC current to trigger Triac [LINK] explains the internal working of a zero-cross SSR. Confusion with TRIAC firing and zero crossing point [LINK] . Counterfeit Fotek SSRs It appears that you are considering Fotek SSRs. Read this first: UL warns of solid state relay with counterfeit UL Recognition Mark (Release 13
Cites Transistor · 2020-02 · Electrical Engineering Stack Exchange · on “FOTEK SSR replacing the Triac”
This may be of interest: UL warns of solid state relay with counterfeit UL Recognition Mark (Release 13PN-52) [LINK] . See also Big Clive's Teardown of an eBay 25A Solid State Relay (SSR) [this video] .
Cites Transistor · 2024-01 · Electrical Engineering Stack Exchange · on “Voltage detected on output SSR while in "OPEN" state”
**Counterfeit Fotek SSRs** It appears that you are considering Fotek SSRs. Read this first: UL warns of solid state relay with counterfeit UL Recognition Mark (Release 13PN-52) [LINK] . See also Big Clive's Teardown of an eBay 25A Solid State Relay (SSR) [this video] .
Critical Transistor · 2020-03 · Electrical Engineering Stack Exchange · on “SSR altern symbol why”
The '~' (tilde) symbol tells you that it is for AC. Internally it is using a triac and these are only suitable for AC switching. The -| |- symbol represents a normally open contact and is common on North American electrical schematics. The 24-380VAC text indicates that it is rated for switching voltages in that range (which excludes DC). Counterfeit Fotek SSRs It appears that you are considering Fotek SSRs. Read this first: UL warns of solid state relay with counterfeit UL Recognition Mark (Release 13PN-52) [LINK] . See also Big Clive's Teardown of an eBay 25A Solid State Relay (SSR) [this video] .