ABB 1VCF339751S8909 Medium Voltage Vacuum Circuit Breaker

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    • Product Code: 1VCF339751S8909
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    ABB 1VCF339751S8909 - Intermediate Technical Document
    ABB 1VCF339751S8909
    Medium Voltage Vacuum Circuit Breaker | Intermediate Technical Document | Revision 1.0 | Date: 2026-02-28
    1. Device Overview
    The ABB 1VCF339751S8909 is a medium voltage (MV) vacuum circuit breaker designed for indoor switchgear applications, providing reliable protection and control for electrical distribution systems in industrial, commercial, and utility environments.
    Engineered with vacuum interrupter technology, this circuit breaker offers high dielectric strength, low maintenance requirements, and long mechanical/electrical life, suitable for rated voltages up to 12kV and short-circuit current interruption up to 31.5kA.
    2. Technical Specifications
    Part Number
    1VCF339751S8909
    Rated Voltage
    12 kV (50/60 Hz)
    Rated Current
    1250 A (Continuous), 2000 A (Short-time)
    Short-Circuit Breaking Capacity
    31.5 kA (3s), 25 kA (1s)
    Operating Mechanism
    Spring-Operated (Manual/Electrical)
    Control Voltage
    220V DC / 110V DC / 230V AC
    Insulation Class
    LI 75kV, SI 35kV
    Mechanical Life
    10,000 Operations (Minimum)
    IP Rating
    IP4X (Integrated in Switchgear)
    3. Installation & Operation
    1 Ensure the switchgear compartment is de-energized and grounded before breaker installation (follow LOTO procedures).
    2 Slide the breaker into the designated compartment and engage the locking mechanism to secure it in position.
    3 Connect control wiring (closing/opening coil, auxiliary contacts) to the terminal block as per wiring diagram.
    4 Charge the spring mechanism (manual crank or electrical motor) and verify charge indicator shows "READY".
    5 Perform functional test (close/open operations) to verify mechanical and electrical interlocks work correctly.
    6 Energize the switchgear and monitor breaker status via protective relay system or SCADA interface.
    Important Safety & Maintenance Notes
    • Only qualified electrical personnel should perform installation, maintenance or testing of the circuit breaker.
    • De-energize and ground all associated circuits before opening the breaker compartment or performing any work.
    • Do not operate the breaker if the vacuum interrupter shows signs of damage (e.g., discoloration, gas leakage).
    • Inspect contact wear every 2000 operations or 2 years (whichever comes first) and replace if wear exceeds 3mm.
    • Lubricate mechanical linkages annually with ABB-approved lubricant to ensure reliable operation.
    • Test insulation resistance (megger test) every 3 years to verify dielectric integrity of the breaker.
    • Store spare vacuum interrupters in a dry, dust-free environment to prevent contamination of vacuum chamber.

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