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Member #913538

Member Since: March 10, 2017

Country: United States

  • To be compliant with UL60950 you have to design for a single point failure. That's why there is an isolated supply and optocouplers - it doesn't matter what relay you use. If there is a breakdown between the contacts on a relay and the coil, the features I just described will prevent hazardous voltages from reaching your Raspberry Pi and everything attached to it.

    The slot gap and trace spacing were all designed for 120VAC operation. Don't be fooled by some of those low cost relay boards from China - yes they may be less expensive but they will not protect you from a single point failure. And unless you put those things inside of a sealed box, they are inherently unsafe. For more on this see: http://pi-plates.com/the-problem-with-relays

  • The relays are UL approved for 1 amp operation but they're labeled as being capable of operating at 2 amps. So we chose to be conservative in our specifications.

  • EN60950-1 To be clear: this board was designed to -comply- with UL60950. It was never submitted to UL for approval. I'm not sure about number 1 in your comments - many firms I work with are still designing for this standard. And without doing a detailed examination of the product for trace spacing, creepage, clearance, and single point failure evaluation, I don't see how you came to your conclusion for your 2nd comment.

  • Pi-Plates communicate to the Raspberry Pi via the SPI interface. This limits the effective A/D sampling rate to about 1000 samples per second. The 50Khz bandwidth mentioned in another comment here is the maximum allowed input frequency.

  • This is not a new term - we came up with it about 3 years ago while trying to think of a product name that would associate the RPi to a family of stacking boards. Thus the names "Pi-Plates." I believe Adafruit came up with it before we did.

    HATS came after we had already designed a few boards. And while they're nice and tidy, they don't lend themselves to stacking very well. In addition, the EEPROM identification strategy is too simplistic for our needs.

    For a more detailed examination of our opinion of HATS, see our blog posting "The Problem with HATS" at http://pi-plates.com/the-problem-with-hats/

No public wish lists :(