Regularly calibrating digital multimeters (DMMs) ensures they provide accurate measurements essential for quality processes. Time, environmental conditions and physical use can alter a DMM’s characteristics, so calibration verifies that its performance meets required specifications.
- Calibration interval: A common calibration interval for DMMs is once per year, though this can vary depending on usage and operating conditions【692632216054878†L589-L592】.
- Choose the right calibrator: Select a calibrator whose specifications are at least four times more precise than the DMM under test and that covers the same functions【692632216054878†L596-L603】.
- Calibration sequences: Perform pre‑adjustment tests, adjust if necessary, then conduct post‑adjustment calibration to document “as found” and “as left” data【692632216054878†L623-L633】.
- Calibration procedure: Using a multi‑product calibrator like the Fluke 5522A, connect the DMM’s V and COM terminals to the calibrator. Test each function and range: – Direct voltage: Apply a known 10‑volt DC output and adjust the calibrator while monitoring error values【692632216054878†L650-L664】.
– Alternating voltage: Set an AC voltage (for example 10 V at 60 Hz) and cycle through waveforms to verify accurate RMS and peak measurements【692632216054878†L678-L695】.
– Resistance and other functions: Use the calibrator’s resistance and current outputs to verify the DMM’s ranges, following the manufacturer’s recommended test points.
Document results in a calibration report, including the DMM’s serial number, calibration date, pass/fail limits and any adjustments made. Maintaining regular calibration ensures your multimeter remains reliable for precise measurements.