Tech Tip: Voltage Output of the SD-RO1 Spot Detector with Relay Output

RLE Technologies customers often want to use our SD-R01 spot detector to drive an external load, like an audible alarm or a pump.  RLE does not currently have a leak detection product with a powered output. The SD-R01, like other RLE Technologies leak detection products, has a non-powered output: a Form C relay output.

The Form C relay output is essentially two switches, one closed or “on” during normal operation, and one open or “off” during normal operation. When a leak is detected, the normally closed (or NC) switch opens or turns “off,” and the normally open (or NO) switch closes or turns “on.”

The relay connection on the SD-RO1 and other RLE products consists of three terminals: one for the NC output, one for the NO output, and a common input (COM) for both sides.

If you want to signal a Normal condition by lighting a green LED and a Leak condition by lighting a red LED, attach the leads of the power source and LEDs to the SD-RO1 as follows:

  • Attach the positive lead of a DC power source for the LEDs to the COM terminal.
  • Attach the positive lead of the green LED to the NC terminal.
  • Attach the positive lead of the red LED to the NO terminal.

After grounding the negative leads of the DC power source and the LEDs, the user has a simple red/green alarm circuit.

If you want to drive a load significantly larger than a pair of LEDs, you can attach a larger power source, AC or DC, to the COM terminal of the relay output.  The SD-RO1 relay can handle up to 1 A @ 24 VDC, or 0.5A resistive @ 120 VAC.  Check our product datasheets for other RLE product output ratings.

 

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