White PaperTest & Measurement
High Accuracy High-Voltage Measurement
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One of the first principals learned as an engineering student is the “observer effect” which states that simply observing a situation or phenomenon necessarily changes that phenomenon. This is often the result of instruments that, by necessity, alter the state of what they measure in some manner. Accurate high voltage measurement is a clear example of the validity of this theory.
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Overview
The white paper from Vitrek Inc. discusses the critical aspects of high-voltage measurement, defining "high voltage" as ranging from 1 kV to 150 kV, applicable to both AC and DC. Accurate high-voltage measurement is essential across various industries, including analytical instruments, defense, aerospace, medical technology, and semiconductor manufacturing. The paper emphasizes that measurement accuracy is influenced by three primary factors: environmental conditions, errors introduced by measurement probes, and the intrinsic performance of the measuring instruments.
One of the key points highlighted is the "observer effect," which suggests that the act of measuring can alter the phenomenon being measured. This is particularly relevant in high-voltage scenarios where electromagnetic effects can introduce significant errors. For instance, even minor movements near the measurement setup can impact accuracy. The Vitrek 4700 Precision High Voltage Meter is presented as a reliable tool for high-voltage measurements, capable of measuring voltages up to 10 kVrms directly, with warnings regarding safety and proper usage.
The paper outlines the importance of probe location, stating that full accuracy specifications are valid only when no objects are within an 18-inch radius of the probe. For higher voltages, such as with the 150 kV probe, this radius increases to 48 inches. The document also discusses the use of external probes for voltages between 1 kV and 10 kV, emphasizing the need for proper insulation and safety precautions when handling high voltages.
Additionally, the white paper addresses the design of voltage dividers, which are commonly used to reduce high voltages to levels that can be safely measured by standard instruments. It explains how precision resistors in a voltage divider can mitigate errors due to resistance variation, temperature coefficients, and electromagnetic effects.
Overall, the white paper serves as a comprehensive guide for achieving optimal accuracy in high-voltage measurements, stressing the importance of controlled environments, proper equipment usage, and understanding the factors that can affect measurement reliability. By following the guidelines provided, users can enhance the accuracy and safety of their high-voltage measurement processes.