The DOLD AI 940 Line Breakage Relay series (Aderbruchrelais) is an exemplary engineering safety protection solution manufactured by E. DOLD & SÖHNE GmbH & Co. KG – a prestigious German enterprise with more than 90 years of recognized expertise in relay technology, switchgear, and functional electrical safety. This device is specifically engineered to continuously, reliably, and instantly detect line breakage across one or multiple conductor cores, cable interruptions, or phase failure conditions within 3-phase AC networks powering critical motors and industrial load assemblies.

In demanding heavy-duty industrial operating conditions, especially across mobile mechanics such as crane hoist trolleys, gantry cranes, container spreaders, freight elevators, or long-distance conveyor networks, power supply cables are consistently subjected to cyclic flexing, mechanical stress, and twisting. Over prolonged operation, this inevitably induces metallic fatigue and internal conductor core severance beneath intact outer insulation jackets. If an internal single-core line break goes undetected, the three-phase motor continues running in a single-phasing condition (two-phase operation), generating severe overheating, catastrophic stator winding burnout, and sudden torque breakdown that can trigger major lifting accidents. The DOLD AI 940 line breakage relay decisively mitigates this risk by dynamically monitoring the electrical symmetry and integrity of the 3-phase lines. Upon detection of a severed line conductor, the relay's high-reliability safety contacts de-energize the main control loop within milliseconds, preventing hazardous mechanical drops, fires, and plant downtime.

The DOLD AI 940 series is standardized across the four most prominent industrial worldwide voltages: 3AC 380V, 3AC 400V, 3AC 440V, and 3AC 500V at 50/60Hz. This provides field engineers with seamless plug-and-play compatibility across diverse standard European power systems as well as heavy manufacturing plant networks in Vietnam without requiring step-down auxiliary transformers. Housed within a rugged, flame-retardant thermoplastic enclosure suitable for standard 35mm DIN-rail mounting, it optimizes cabinet space footprint. The front panel features intuitive status LED indicators for immediate power and error diagnostics, facilitating rapid on-site troubleshooting. Fully certified under stringent international safety standards including IEC/EN 60255 and DIN VDE 0435, the DOLD AI 940 represents an indispensable asset for metallurgical plants, port terminals, shipyards, heavy machinery manufacturing facilities, and automated production plants worldwide.

• Manufacturer: DOLD (E. DOLD & SÖHNE GmbH & Co. KG)
• Country of Origin: Germany
• Product Type: Line Breakage Relay / Aderbruchrelais (Rơ le giám sát đứt dây)
• Product Series: AI 940
• Covered Voltage Models:
  - DOLD AI 940 3AC 380V 50/60Hz
  - DOLD AI 940 3AC 400V 50/60Hz
  - DOLD AI 940 3AC 440V 50/60Hz
  - DOLD AI 940 3AC 500V 50/60Hz
• Nominal Frequency: 50 / 60 Hz
• Monitoring Functions: Conductor line breakage detection (Aderbruch), broken supply lines, phase failure in 3-phase networks
• Output Contacts: Industrial heavy-duty changeover contacts (C/O)
• Contact Switching Capacity: AC-15: 3A / AC 230V; DC-13: 1A / DC 24V (compliant with IEC/EN 60947-5-1)
• Visual Status Indication: Front LED indicators for power availability and fault monitoring
• Tripping Reaction Time: Immediate millisecond response upon wire breakage occurrence
• Mounting Configuration: Standard 35 mm DIN-rail mounting (compliant with IEC/EN 60715)
• Terminal Architecture: Robust screw-cage terminal blocks designed to endure continuous mechanical vibrations
• Protection Enclosure Rating: Housing IP40, Terminals IP20 (compliant with IEC/EN 60529)
• Operating Temperature Range: -20°C to +60°C
• Compliant Safety Standards: IEC/EN 60255, IEC/EN 60947-5-1, DIN VDE 0435
• Typical Industrial Applications: Gantry cranes, overhead bridge cranes, hoists, industrial elevators, crushers, heavy motor drives