Multimeter BK5491A — Drift Analysis
Drift analysis and trend monitoring for Multimeter BK5491A.
Assessment
TODO: Review drift history and write metrological assessment.
Internal Specification: Analyt MTC — BK5491A 1-year accuracy specifications
Manufacturer Specification: BK Precision 5491A Manual — 1-year accuracy specifications
DC Current (A)
| Setpoint (A) | 2024 | 2025 |
|---|---|---|
| As-found Dev/Spec — measured error normalized to internal specification | ||
| 0 | +0.40 | +0.40 |
| 0.0004 | +0.40 | +0.40 |
| 0.004 | +0.38 | +0.33 |
| 0.04 | +0.00 | +0.04 |
| 0.4 | +0.08 | +0.04 |
| 2 | -0.49 | -0.39 |
| Inter-calibration drift Dev/Spec (Δ) — change since previous calibration, normalized | ||
| 0 | — | +0.00 |
| 0.0004 | — | +0.00 |
| 0.004 | — | -0.04 |
| 0.04 | — | +0.04 |
| 0.4 | — | -0.04 |
| 2 | — | +0.10 |
Figure 1 shows each calibration's as-found deviation normalized to the internal specification. Values at ±1.0 reach the specification limit. The shaded blue envelope covers the full spread across all setpoints; the amber band adds measurement uncertainty (RSS). For the full methodology, see Equipment Monitoring & Drift Analysis.
Figure 2 shows the drift between consecutive calibrations — how much the device changed since it was last calibrated or adjusted. This isolates the device’s instability from corrections applied during calibration.
DC Voltage (V)
| Setpoint (V) | 2024 | 2025 |
|---|---|---|
| As-found Dev/Spec — measured error normalized to internal specification | ||
| -490 | -0.07 | -0.22 |
| -49 | -0.14 | -0.36 |
| -4.9 | -0.22 | -0.51 |
| -2.5 | +0.00 | -0.33 |
| -1 | +0.33 | -0.17 |
| -0.5 | +0.40 | +0.20 |
| 0 | +0.05 | +0.03 |
| 0.01 | +0.00 | +0.00 |
| 0.25 | +0.08 | +0.08 |
| 0.49 | +0.07 | +0.12 |
| 0.5 | +0.60 | +0.20 |
| 1 | +0.50 | +0.33 |
| 2.5 | +0.56 | +0.56 |
| 4.9 | +0.58 | +0.65 |
| 49 | +0.22 | +0.36 |
| 490 | +0.14 | +0.29 |
| 750 | +0.00 | +0.18 |
| Inter-calibration drift Dev/Spec (Δ) — change since previous calibration, normalized | ||
| -490 | — | -0.14 |
| -49 | — | -0.22 |
| -4.9 | — | -0.29 |
| -2.5 | — | -0.33 |
| -1 | — | -0.50 |
| -0.5 | — | -0.20 |
| 0 | — | -0.03 |
| 0.01 | — | +0.00 |
| 0.25 | — | +0.00 |
| 0.49 | — | +0.05 |
| 0.5 | — | -0.40 |
| 1 | — | -0.17 |
| 2.5 | — | +0.00 |
| 4.9 | — | +0.07 |
| 49 | — | +0.14 |
| 490 | — | +0.14 |
| 750 | — | +0.18 |
Figure 3 shows each calibration's as-found deviation normalized to the internal specification. Values at ±1.0 reach the specification limit. The shaded blue envelope covers the full spread across all setpoints; the amber band adds measurement uncertainty (RSS). For the full methodology, see Equipment Monitoring & Drift Analysis.
Figure 4 shows the drift between consecutive calibrations — how much the device changed since it was last calibrated or adjusted. This isolates the device’s instability from corrections applied during calibration.
