This device is a Solid State Relay (SSR) and differs from a standard relay mainly due to the fact that it is not electro-mechanical. These relays use Triacs to switch the connected load instead of a coil and contacts. They have isolation in the form of an optocoupler, so rest assured that your control circuitry is safe from any high voltages that you may be switching. The article in the Resources section below does a good job of giving a quick comparison between the two types.
You may be wondering why the image for this product shows a 25A SSR, but the product name and description refer to this as being a 12A SSR. Your eyes do not deceive you, there is a reason for this. After doing some research we discovered that many of the SSR’s which are imported from China/Taiwan (Like these) tend to lie about the true ratings of the device. We can confirm that ours fall into this same category and have much lower ratings than the sticker or model number claim. Ours in particular contain a BTA12 Triac which has a max current of only 12A, instead of 25A. Another thing to note is clearance between the input and output traces of the optocoupler, which limits the maximum safe load voltage. The gap between the closest two traces is approximately 0.7mm, and based on the IPC-2221 standard for coated conductors, this is safe for use up 250VAC. In summary, as long as your load voltage and current does not exceed the maximum ratings described above these SSR’s are still perfectly usable.
Features / Specs
- Brand: FQFER
- Model: SSR-25 DA
- Control Voltage: 3 ~ 32VDC
- Load Voltage: 24 ~ 250VAC
- Max Load Current: 12A
- Optocoupler Part Number: MOC3063
- Triac Part Number: BTA12 1000B
- Dimensions: 60mm x 45mm x 22mm
- Mounting Hole Size: M4