Stability - Consistency Over Time and Against Environmental Changes Stability is a measure of how well a power supply can maintain a constant output despite variations in external factors such as input voltage, load, and ambient temperature. It represents the "consistency" or "steadfastness" of the output, showing its ability to resist external influences over time.
Key Factors of Stability in DC Power Supplies
For a DC power supply, stability is typically characterized by its performance against the following factors. The common English terms used in international datasheets are also provided.
| Context | Parameter | Definition | Example |
|---|---|---|---|
| Time Stability | Drift | Output variation over a specified period following a warm-up phase. Critical for long-term operational consistency. | ±0.01% / 8 h |
| Temperature Stability | Temperature Coefficient | Output variation relative to ambient temperature changes. | 50 ppm / °C |
| Input Voltage Variation | Line Regulation | The ability to maintain a constant output voltage or current despite fluctuations in the AC input voltage. | 0.01% / V |
| Load Variation | Load Regulation | The ability to maintain a constant output despite changes in the connected load impedance or current draw. | 0.02% / V |
| Output Voltage Stability | Voltage Regulation | The ability to maintain a stable, constant output voltage under specified operating conditions. This includes both Line Regulation (against input variations) and Load Regulation (against load variations). | ±1 mV |
| Output Current Stability | Current Regulation | The ability to maintain a stable, constant output current under specified operating conditions. This includes both Line Regulation (against input variations) and Load Regulation (against load variations). | ±2 mA |
The Importance of Stability
A highly stable high-voltage power supply or DC power supply ensures reliable, repeatable results, essential for long-term testing, environments with temperature fluctuations, or varying electronic loads. Matsusada Precision engineers products with stability as a core performance metric, ensuring the long-term reliability of our high-voltage amplifiers and bidirectional power supplies.
Distinguishing Stability from "Accuracy" and "Precision"
Stability is evaluated independently from accuracy and precision.
- Accuracy: The closeness of the output to the target value.
- Precision: The repeatability or resolution of the output setting.
- Stability: The consistency of the output against external factors (time, temperature, load) over a duration.
Consider a target analogy: Accuracy is hitting the bullseye. Precision is grouping shots tightly. Stability is the ability to maintain that tight grouping in the same location over time, regardless of wind (environmental changes) or fatigue (time drift). Even if the accuracy is lower (off-center), a highly stable supply guarantees the output remains fixed and predictable.
- Official Definitions and Reference Standards
While "Stability" as a single term is not directly defined in metrology glossaries like the VIM in the same way as accuracy and precision, its individual components are critical performance parameters. These components--such as drift, temperature coefficient, line regulation, and load regulation--are defined and specified in international standards for power supply performance, such as the IEC 60478 series.