Numerical Neutral Displacement Relay is a microprocessor-based relay providing highly sensitive earth fault protection in ungrounded systems. It operates by detecting zero-sequence voltage (neutral displacement), ensuring rapid and reliable isolation for faults that are difficult for conventional protection to clear. As microprocessor-based draw-out units employ fast digital signal processing and advanced algorithms to quickly analyze fault magnitude and duration, ensuring that the circuit breaker isolates only the damaged section of the electrical system.