Sequent Microsystems Unveils a 40A 240V High-Load Relay Board for the Raspberry Pi

Hefty board can be daisy-chained over RS485 for up to 1MW of switching power — enough, its creators claim, for "1,000 homes."

Sequent Microsystems has launched a high-power relay add-on for the Raspberry Pi and compatible single-board computers or programmable logic controller (PLC), offering — the company claims — enough grunt to switch the power for "1,000 homes" from a single Raspberry Pi.

"Switching very high power loads is challenging," says Sequent's Mihai Beffa of the problem the company's latest board design seeks to solve. "Large current loads require specialized power relays, heavy contacts and very wide traces on PCB. This card solves all three issues, being able to switch three circuits of 40A/240VAC."

The board itself houses three heavy-duty relays, each one of which can handle 40A at up to 240V. Those alone aren't enough to handle the needs of the claimed "1,000 houses," of course, but the cards can be daisy-chained together via an RS485 connection — and if you pick up 32 individual cards, that's a total of 921.6KW of switching capacity for the headline "1,000 homes" claim.

There are other tricks up the board's sleeve, too: Sequent has demonstrated how three boards chained together can handle the soft-start requirements of a three-phase 25KW motor as an alternative to "a Star-Delta starter like [the] Schneider Electric LC3D32AF7, which you can buy for $2,244."

While primarily designed for the Raspberry Pi, Sequent is quick to point out the board's broader compatibility: "We tested the card with a cheap, $35 Orange Pi and it worked flawlessly," Beffa says. "We also tested the card with [a] BeagleBone using our adapter and with ROCK Pi (direct plugin)." The board can also be used with a PLC supporting RS485 and the MODBUS protocol.

The high-load relay board is now funding on Kickstarter, with physical rewards starting at $50 for the board, connectors, standoffs, and DIN rail brackets. Fulfillment is expected to begin in November this year.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire:
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