Siemens FD63T125 Molded Case Circuit Breaker Trip Unit

Description:

The Siemens FD63T125 Trip Unit is used in FD-frame molded case circuit breaker systems to provide thermal-magnetic overload and short-circuit protection for industrial electrical distribution circuits. Commonly installed in Siemens FD series circuit breakers within switchboards, motor control centers, and industrial power distribution panels operating up to 600V AC. Maintenance teams, OEM panel builders, and electrical contractors use this trip unit for breaker repair, frame upgrades, retrofit work, and replacement of failed or mismatched protective trip modules.

Applications:

The Siemens FD63T125 trip unit is commonly used in industrial and commercial electrical distribution systems including feeder protection panels, motor control centers, HVAC power distribution, manufacturing equipment, and facility electrical infrastructure where 125A circuit protection is required in FD-frame breaker assemblies.

Technical Specifications:

• Manufacturer: Siemens
• Model / Part number: FD63T125
• Product type: Interchangeable trip unit
• Frame compatibility: FD-frame circuit breakers
• Poles: 3-pole
• Rated current: 125A
• Voltage rating: up to 600V AC
• Trip type: Thermal-magnetic (long-time and instantaneous protection)
• Function: Overload and short-circuit protection
• Mounting: Plug-in trip unit for FD series breaker frame
• Standards: UL 489 / IEC compliant FD-frame system

Common Replacements:

• Siemens FD63T125R equivalent trip unit (revision variant)
• Siemens FD63T125L complete breaker assembly configuration
• Eaton FD-frame equivalent 125A 3P interchangeable trip unit assembly