The Basler Electric BE1-50/51M-109 stands as the industry benchmark for electromechanical overcurrent protection, delivering uncompromising reliability in power generation and distribution systems since its inception. This time-tested relay combines rugged mechanical construction with precision-calibrated induction disk operation, offering both instantaneous and time-delayed overcurrent protection. The BE1-50/51M-109 features field-adjustable pickup settings (0.5-12A) and time dial adjustments (0.1-10 seconds), providing exceptional versatility across diverse protection schemes.
As a cornerstone of Basler’s protection product portfolio, the BE1-50/51M-109 excels in applications where analog reliability surpasses digital complexity. Its oil-damped induction disk mechanism maintains ±5% timing accuracy across the full operating range (-40°C to +60°C). The Basler Electric BE1-50/51M-109 remains the preferred solution for legacy system retrofits and environments with severe electromagnetic interference that could disrupt digital relays.
Technical Specifications
Product Model | BE1-50/51M-109
Manufacturer | Basler Electric
Product Type | Electromechanical Overcurrent Relay
Rated Current | 5A standard (1A optional)
Frequency Range | 50/60Hz ±10%
Current Range | 0.5-12A continuously adjustable
Time Dial Range | 0.1-10 (11 discrete positions)
Time Curves | CO-2 through CO-11
Operating Accuracy | ±5% of setting
Reset Characteristic | 95% within 40ms
Contact Rating | 30A make/10A break (resistive)
Operating Temperature | -40°C to +60°C
Dielectric Strength | 2.5kV RMS for 1 minute
Vibration Resistance | 5G peak (5-500Hz)
Dimensions | 133×133×178mm (H×W×D)
Weight | 2.3kg
Certifications | UL 508, CSA C22.2 No.14
Key Features and Advantages:
The BE1-50/51M-109 delivers legendary durability through stainless steel bearings and silver-cadmium oxide contacts rated for 10,000 full-load operations. Its oil-damped mechanism maintains ±2% timing accuracy over decades – outperforming many digital relays in long-term stability. The relay’s purely electromechanical design eliminates software vulnerabilities and maintenance headaches associated with firmware updates.
Industrial-grade reliability: Over half-million global installations since 1968 demonstrate the BE1-50/51M-109’s exceptional performance in harsh conditions. The hermetically sealed movement compartment resists dust, moisture and corrosive atmospheres that degrade electronic components. Maintenance teams value the visible operation indicator and manual trip lever for simplified testing without external equipment. The relay’s analog nature provides inherent immunity to cyber threats targeting modern digital protection systems.
Application Fields:
In utility substations, the BE1-50/51M-109 provides reliable backup protection for transformers and feeders, where its predictable time-current characteristics ensure perfect coordination with upstream/downstream devices. Heavy industries deploy these relays for motor protection, particularly in steel mills and mining operations where electromagnetic interference compromises digital relay reliability.
The Basler Electric BE1-50/51M-109 thrives in offshore platforms where salt spray and vibration would disable sensitive electronics. Its -40°C cold-start capability guarantees protection system availability in Arctic power stations, while the absence of software eliminates freeze-up risks. The relay remains specified for nuclear facilities due to its analog reliability and proven seismic performance (IEEE 344 qualified).
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Installation and Maintenance:
Installation preparation: The BE1-50/51M-109 requires CT circuit verification (5A/1A) before energization. Maintain minimum 50mm clearance for heat dissipation and use copper conductors (≥2.5mm²) for current inputs. Mount using all four provided holes with M6 hardware (8Nm torque).
Maintenance recommendations: Conduct annual operational tests at 125% pickup current to verify timing. Replace damping oil decennially or if contamination appears. Clean contacts with Basler-approved cleaner (BE1-CL-100) during major outages. Document all test results for performance trending.
Product Assurance:
Basler Electric warrants the BE1-50/51M-109 for 12 months against mechanical and electrical defects.
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