Maintenance for working electrical systems can be broadly categorized into:
Preventive Maintenance (PM): Scheduled maintenance to prevent breakdowns and extend equipment life.
Predictive Maintenance (PdM): Using monitoring and analysis to predict when maintenance is needed.
Corrective Maintenance (CM) / Breakdown Maintenance: Repairing equipment after it has failed.
Proactive Maintenance: A combination of PM and PdM, focusing on root cause analysis and continuous improvement.