Description
DEIF
UNI-LINE
TYPE: RMP-121D
REVERSE POWER RELAY
247110.30
SUPPLY: 440V AC
MEAS VOLTAGE: 450V / MODULE: 240V
MEAS CURRENT: – / MODULE: 0.8A
MEAS POWER: 450W / SCALE: 0.78
COUPLING: 1W3
600V CAT III.
The DEIF RMP-121D is a Uni-Line series reverse power relay engineered to detect reverse power flow conditions within shipboard AC electrical networks. Operating on a 440V AC supply and rated to CAT III 600V, it is designed to protect generators and power distribution systems from the damaging effects of motoring — where a generator begins drawing power from the busbar rather than supplying it. As a critical component within the marine control system, this relay ensures generator sets and paralleling arrangements operate within safe parameters, protecting prime movers and maintaining grid stability aboard commercial and industrial vessels.
Key Features
✓ Reverse power detection function with a measured power reference of 450W and a calibrated scale factor of 0.78, providing accurate and repeatable trip thresholds within the Uni-Line protection scheme.
✓ Supply voltage of 440V AC with a measurement voltage input of 450V and module voltage of 240V; module current rating of 0.8A; rated to 600V CAT III for safe integration into shipboard medium-voltage panels, subject to confirmation of site conditions.
✓ Single-phase, three-wire coupling configuration (1W3), making it compatible with standard three-phase generator monitoring arrangements typically found in DEIF Uni-Line power management and generator protection panels.
✓ Designed for installation within dedicated protection relay enclosures or switchboard panels in dry, controlled environments such as the engine control room or main switchboard room; compliance with relevant marine installation categories subject to vessel-specific survey confirmation.
✓ A direct replacement component for existing DEIF Uni-Line installations, supporting like-for-like service exchanges and minimising reconfiguration requirements during maintenance or overhaul operations.
Marine Applications
✓ Generator protection on main and emergency switchboards aboard cargo vessels, tankers, bulk carriers, and offshore support vessels where parallel generator operation is standard practice.
✓ Power management systems requiring reverse power protection during load sharing, synchronisation, and bus-tie operations to prevent generator motoring events.
✓ Integration within DEIF Uni-Line generator control and protection panels on vessels with fixed or variable speed diesel-electric or conventional propulsion arrangements.
✓ Retrofit or replacement within existing marine power management systems during scheduled dry-dock maintenance, machinery surveys, or following relay failure or calibration drift.
✓ Applicable across a broad range of vessel types including RoRo ferries, platform supply vessels, dredgers, cable-layers, and naval auxiliaries where robust generator protection is operationally critical.
Why Marine Engineers Choose
The DEIF RMP-121D is a well-established protection relay within the Uni-Line product family, offering reliable reverse power detection in a form factor and interface familiar to engineers working with DEIF power management architectures. Its defined measurement parameters and CAT III voltage rating make it a dependable choice for shipboard generator protection in demanding marine environments.
Ideal For
Cargo ships, tankers, bulk carriers, offshore support vessels, ferries, platform supply vessels, dredgers, and any commercial or industrial vessel operating DEIF Uni-Line generator control and protection systems requiring reverse power relay functionality.
Technical Support & Compliance
Technical assistance is available to support remote troubleshooting, onboard diagnostics, testing and commissioning guidance, and integration of this relay within existing DEIF power management panel configurations. Retrofit and upgrade support can be provided where system compatibility needs to be assessed. To confirm suitability for your installation — subject to confirmation — buyers are advised to share nameplate photographs, the full part number (247110.30), any available panel drawings or wiring diagrams, the system model and software version where applicable, and vessel name or IMO number. This information ensures accurate cross-referencing and avoids compatibility issues prior to installation.
