#3 - DC voltage measurement

⚡ How to Measure DC Voltage Reliably in an Industrial Environment

Many consider DC voltage measurement a basic task – but in industrial practice, reliability depends on the details. Here are some practical tips to keep in mind when designing a measurement system:

🔹 Use temporal averaging to filter out noise
Real-world DC signals are almost always affected by noise. Don’t rely on a single instantaneous value – determine a stable equilibrium level.
👉 Tip: A 20 ms (1/50 Hz) average is a good baseline for filtering out line frequency disturbances.

🔹 Choose your reference point carefully
Voltage is always measured relative to something. The most reliable approach is to reference directly to the DUT ground.
👉 Avoid referencing from other parts of the measurement system – this can introduce additive interference.

🔹 Route the signal simply, but intentionally
Standard cabling may be sufficient, but always ensure proper shielding and grounding, especially for sensitive measurements.

🔹 Ensure consistent referencing during multiplexing
When switching between multiple measurement points (e.g., via relay matrix), make sure all channels share the same reference.
👉 If references differ, controlled switching is necessary to prevent shorts or incorrect readings.

🔹 Don’t load the signal source
Use high input impedance instruments (e.g., DMM or PC-based AI cards) to avoid disturbing the source signal.

Download DCVoltageMeasurement.pdf