The ABB VD4M 1212-31 is a medium-voltage, indoor, vacuum circuit breaker belonging to the renowned ABB VD4 family. The "M" suffix typically indicates a motor-driven, spring-operated stored energy mechanism, designed for frequent operations and remote control.

Engineered for accuracy and reliability, the Emerson EPRO PR9268/200-000 Electrodynamic Velocity Sensor delivers precise velocity measurements across industrial applications, ensuring optimal performance and safety.

This relay serves as a fundamental backup or primary protection device in medium-voltage (MV) and high-voltage (HV) networks. Its core principle is to measure the current via connected Current Transformers (CTs) and, if the current exceeds a preset threshold for a duration defined by an inverse time curve, it mechanically closes its output contacts to trip a circuit breaker. Its self-powered nature makes it exceptionally reliable and ideal for critical protection where control power failure must not compromise safety.