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.
Parameter English Term(s) Description
- Time Stability
- Drift / Time Stability The change in output over a specified period. Crucial for maintaining performance in long-duration operations (e.g., ±0.01% / 8h).
- Temperature Stability
- Temperature Coefficient The change in output due to variations in ambient temperature. Often expressed in parts per million per degree Celsius (e.g., 50ppm/°C).
- Input Voltage Variation
- Line Regulation The ability of the output to remain constant despite changes in the AC input voltage.
- Load Variation
- Load Regulation The ability of the output to remain constant despite changes in the connected load (current draw).
The Importance of Stability
A highly stable high voltage power supply or DC power supply delivers reliable and repeatable results, even during long-duration endurance tests, in environments with significant temperature fluctuations, or in applications with a varying electronic load. At Matsusada Precision, we consider stability a critical performance metric to ensure the long-term reliability of our products, including our high voltage amplifiers and bidirectional power supplies.
Difference from "Accuracy" and "Precision"
Stability is evaluated on a different axis from accuracy and precision.
- Accuracy: "Correctness" against the target value.
- Precision: "Repeatability" of the output values.
- Stability: "Consistency" against external factors (time, temperature, load, etc.).
Using the target analogy, stability is the ability to keep hitting the same spot, regardless of external conditions like wind or the passage of time. Even if the shots are slightly off-target (low accuracy), if they all remain tightly grouped in the same location over time, the performance is considered "highly stable."
- 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.