Which of the following is primarily monitored in an EMS quality code?

In an Energy Management System (EMS), quality codes are used to ensure that the data being monitored and analyzed is accurate and reliable. Monitoring data integrity is crucial because the decisions made based on this data can significantly affect the operation and reliability of the power grid. If the data quality is compromised, it could lead to incorrect assessments of system states, potentially resulting in operational issues or constraints that could impact service reliability.

While aspects like voltage levels, frequency shifts, and load distributions are important parameters monitored in an EMS, they are primarily related to the operation and stability of the power system rather than the quality of the data itself. Ensuring data integrity helps maintain the overall trustworthiness of the system's measurements and analytics, which is the main focus when discussing EMS quality codes.