Siemens 3UG4615-1CR20 3 Pole digital line monitoring relay with screw-type terminals. The field-proven SIRIUS monitoring relays for electrical and mechanical quantities enable constant monitoring of all important characteristic quantities that provide information about the functional capability of a plant. Both sudden disturbances and gradual changes, which may indicate the need for maintenance, are detected. Through relay outputs, the monitoring relays enable direct disconnection of the affected system components as well as alarming (e.g. by switching a warning lamp). To respond flexibly to brief faults such as voltage dips or load changes, the monitoring relays have settable delay times. This avoids unnecessary alarms and disconnections while enhancing plant availability.