1. Safety Precaution:
Grounding the positive terminal helps ensure the safety of the personnel performing the IR test. When the positive terminal is grounded, it reduces the risk of electrical shock by providing a low-impedance path for any leakage current to flow.
2. Mitigation of Surface Leakage Currents:
Electrical equipment often has surfaces that are not perfectly insulating and may exhibit some degree of surface leakage. Grounding the positive terminal helps mitigate the impact of surface leakage currents by providing an alternative path for these currents to flow. This reduces the influence of surface leakage on the IR measurement, resulting in more accurate and reliable results.
3. Reduction of Capacitive Effects:
Electrical equipment can exhibit capacitance between its conductors and the surrounding environment. When the positive terminal is grounded, it reduces the capacitive coupling between the equipment and the ground, minimizing the influence of capacitive effects on the IR measurement.
4. Improved Accuracy:
By mitigating the effects of surface leakage currents and capacitive effects, grounding the positive terminal of the megger contributes to more accurate and reliable insulation resistance measurements. Accurate IR measurements are crucial for assessing the health of electrical insulation and ensuring the safety and reliability of electrical systems.
In summary, grounding the positive terminal of a megger during IR measurement of electrical equipment enhances safety, minimizes the influence of surface leakage currents and capacitive effects, and ensures accurate and reliable insulation resistance measurements.
