The DOLD AK9840.82 Asymmetry Relay (Asymmetrierelais) is a benchmark industrial protection component engineered and manufactured by E. DOLD & SÖHNE GmbH & Co. KG in Germany—a globally renowned pioneer in electrical safety and switching technologies. Within three-phase power networks, voltage unbalance between phases frequently arises from asymmetrical single-phase load distribution, degraded transformer windings, or high-resistance terminal connections. Even a minor voltage unbalance of 2% to 3% can induce reverse-sequence current amplification within electric motors by 6 to 10 times, generating extreme thermal dissipation that accelerates winding insulation breakdown, produces opposing braking torque, causes severe mechanical vibrations, and ultimately results in catastrophic motor burnout.

The DOLD AK9840.82 series is meticulously engineered to decisively eliminate these operational hazards through continuous dynamic analysis of voltage amplitude symmetry and angular phase displacements across 3-phase AC networks. The unit empowers maintenance engineers to precisely configure asymmetry threshold limits and response time delays, effectively filtering out transient voltage dips during motor startup cycles. Featuring the signature ".82" suffix configuration, it incorporates two independent changeover contacts (2 C/O), delivering substantial switching capacity to simultaneously isolate the motor's main contactor control loop and transmit alarm telemetry to central PLCs or visual field indicators.

A definitive engineering highlight of the AK9840.82 series is its extensive coverage of rated operational voltages spanning low to extreme industrial ratings: 110V, 127V, 190V, 208V, 220V, 240V, 380V, 400V, 415V, 440V, 460V, 480V, 500V, 550V, 600V, 660V, and 690V at 50/60Hz. This exhaustive compatibility allows seamless deployment across North American, European, and Asian electrical standards, as well as specialized heavy mining, marine, and offshore platforms in Vietnam without necessitating auxiliary potential transformers. Encapsulated in a flame-retardant industrial enclosure tailored for 35mm DIN-rail mounting, it optimizes cabinet space. Integrated dual front LEDs provide instantaneous visual status indication of operational health and asymmetry fault conditions, ensuring intuitive on-site diagnostics. It is an indispensable asset for heavy pumping stations, industrial compressor packages, ventilation blowers, and automated processing lines.

• Manufacturer: DOLD (E. DOLD & SÖHNE GmbH & Co. KG)
• Country of Origin: Germany
• Product Series: AK9840
• Contact Configuration Code: .82 (2 independent changeover contacts / 2 C/O)
• Technical Category: Voltage Asymmetry Monitoring Relay (Asymmetrierelais)
• Supported Voltage Models in this entry:
  - AK9840.82 3AC 110V 50/60Hz
  - AK9840.82 3AC 127V 50/60Hz
  - AK9840.82 3AC 190V 50/60Hz
  - AK9840.82 3AC 208V 50/60Hz
  - AK9840.82 3AC 220V 50/60Hz
  - AK9840.82 3AC 240V 50/60Hz
  - AK9840.82 3AC 380V 50/60Hz
  - AK9840.82 3AC 400V 50/60Hz
  - AK9840.82 3AC 415V 50/60Hz
  - AK9840.82 3AC 440V 50/60Hz
  - AK9840.82 3AC 460V 50/60Hz
  - AK9840.82 3AC 480V 50/60Hz
  - AK9840.82 3AC 500V 50/60Hz
  - AK9840.82 3AC 550V 50/60Hz
  - AK9840.82 3AC 600V 50/60Hz
  - AK9840.82 3AC 660V 50/60Hz
  - AK9840.82 3AC 690V 50/60Hz
• Nominal Operating Frequency: 50 / 60 Hz
• Monitoring Parameters: 3-phase voltage asymmetry (unbalance), total phase failure, incorrect phase sequence
• Asymmetry Setting Range: Adjustable threshold limits based on percentage unbalance
• Output Contact Configuration: 2 Changeover contacts (2 C/O)
• Switching Capacity: AC-15: 3A / AC 230V; DC-13: 1A / DC 24V (compliant with IEC/EN 60947-5-1)
• Visual Diagnostics: Front LED indicators for power healthy and asymmetry trip conditions
• Mounting Architecture: Quick snap-on mounting on standard 35 mm DIN-rail (IEC/EN 60715)
• Connection Terminals: Vibration-proof box clamp screw terminals
• Protection Rating: Housing IP40, Terminals IP20 (IEC/EN 60529 compliant)
• Ambient Temperature Range: -20°C to +60°C
• Compliant Standards: IEC/EN 60255, IEC/EN 60947-5-1, DIN VDE 0435
• Common Industrial Deployments: 3-phase AC motors, compressors, HVAC chillers, water pumps, ATS panels, power distribution boards