0–50V Voltage Sensor Output Troubleshooting

Hi everyone,
My company has several ATO sensors for various detection and measurement tasks. Recently, we ran into a problem with one of our 0–50V voltage sensors (SKU: ATO-VOS-ACDC500).
Specs:
Measuring Range: 0–50V
Output Signal: 0–10V
Power Supply: 24V DC
Here’s the issue:
When we apply 24V to the sensor’s U(+) and U(–), the Uz output pin gives –2V, which would correspond to –10V on the scaled range. Obviously, this makes no sense, so I'm trying to figure out whether something is wrong with the sensor itself or if something in our setup is off.
Any ideas on what might be causing the negative output, or how to properly troubleshoot this model? If the unit is bad, we’ll need replacements soon—we rely on these sensors for almost every test.
Thanks in advance!

Emily wrote:Hi Emily, from the description of your test results, it’s safe to conclude that the sensor is defective.
For reference, here are the standard test steps for this model (which you may have already followed):
1. Wire the product correctly according to the wiring diagram.
2. Power the sensor with 24V DC.
3. Measure the voltage value at the input terminals and record the xV reading.
4. Measure the voltage value at the output terminals and record the yV reading.
5. Check whether the ratio x : y ≈ 5 : 1.
You can purchase a replacement unit here (please specify whether you will be measuring AC or DC so we can calibrate it correctly before shipment): [https://www.ato.com/ac-dc-voltage-sensor-75mv-to-500v]

ATO wrote:Thank you. Based on the troubleshooting and your feedback, it appears that the sensor has failed. We’ll order replacements and specify DC calibration as suggested. Appreciate the quick help!