When is the GMD procedure activated?

The GMD (Geomagnetic Disturbance) procedure is activated specifically when 10A or greater is measured by designated equipment. This measurement indicates a significant change in geomagnetic activity that can affect the performance of the electrical grid. The procedure aims to mitigate potential impacts of geomagnetic storms, which can induce harmful currents in transmission systems, especially during intense solar activity.

Monitoring for these currents allows grid operators to anticipate and react to potential infrastructure issues that could arise due to geomagnetic effects. By activating the GMD procedure based on the specified current threshold, operators can take appropriate actions to protect the system, such as adjusting transformer tap settings or temporarily reducing loads.

This focus on a specific current level is crucial because it provides a clear and measurable indication of when the grid may be at risk due to geomagnetic influences, allowing for timely and effective responses.