Where should the grounding impedance device be installed?

The grounding impedance device should be installed at the system neutral point. This location is significant because the neutral point is the point in a three-phase system where the phases are balanced, allowing for stable operation and grounding. By grounding at the neutral point, you provide a return path for fault currents, ensuring that any fault conditions can be cleared effectively, which enhances the safety and reliability of the electrical system.

In practice, grounding at the system neutral point helps minimize voltage gradients and potential differences between grounded objects, reducing the risk of electric shock or equipment damage. It creates a reference point for the system voltage and helps maintain system stability during normal operation and under fault conditions.

Other options would not provide the same level of safety and system performance. For example, placing the grounding impedance device within the transformer enclosure may not adequately address ground fault conditions since it does not establish a direct connection to the system's neutral point. Similarly, grounded installations at the center point of the transformer secondary or at the primary overcurrent protective device (OCPD) may not ensure that the entire system is properly referenced and protected under fault conditions.