Maintenance Strategy (Preventive, Corrective, Predictive)

The classification of maintenance forms for electrical installations and equipment according to the timing and trigger of the intervention, distinct from the legally mandatory periodic NEN 3140 inspection itself: corrective maintenance intervenes only after a fault or defect has occurred (reactive, often unplanned and costly due to production downtime); preventive maintenance takes place at fixed, predetermined time intervals or numbers of operating hours, regardless of the actual condition of the component (for example routinely replacing a circuit breaker after X switching cycles); and predictive maintenance bases the intervention moment on the actually measured condition and degradation trend of the component, using techniques such as thermography, vibration analysis, partial-discharge diagnostics or oil-gas analysis, so that maintenance is carried out precisely when needed — neither too early (wasting still-usable service life) nor too late (risking unexpected failure). In practice, installation-responsible persons often combine all three strategies within a single maintenance plan, whereby critical, hard-to-replace components (transformers, main circuit breakers) are monitored predictively while less critical, inexpensive components are replaced preventively on a fixed schedule.