Siemens 3VL9440‑7DC30 Thermal‑Magnetic Trip Unit

Siemens 3VL9440‑7DC30 is a 3‑pole thermal‑magnetic trip unit for SENTRON 3VL VL400 molded‑case circuit breaker. It provides adjustable overload and short‑circuit protection for power distribution circuits, detecting abnormal current and triggering breaker tripping to protect downstream cables and electrical loads.

This trip unit supports adjustable current setting range IR 320‑400A, with short‑circuit protection threshold 2000‑4000A. It adopts screw terminal connection design, complies with IEC 60947 standard, widely used as replacement spare parts for industrial power distribution cabinet maintenance and retrofitting projects.

Main Specifications

• Brand: Siemens
• Model: 3VL9440‑7DC30
• Product Type: Thermal‑Magnetic Trip Unit
• Pole: 3‑pole
• Rated Current: 400A, adjustable IR:320‑400A
• Short‑circuit protection: 2000‑4000A adjustable
• Rated Operating Voltage: Up to 690V AC
• Matching Device: VL400 molded‑case circuit breaker
• Certification: IEC 60947 industrial standard
• Operating Temperature Range: -25°C ~ +70°C

Core Functions

• Thermal overload protection against long‑time over‑current of power distribution loop
• Magnetic short‑circuit protection for fast tripping when short‑circuit fault occurs
• Support adjustable overload and short‑circuit threshold to match different load characteristics
• Directly assemble into VL400 circuit breaker body as protection core component
• Screw‑type terminal connection ensures stable wiring for high‑current application
• Accurate fault detection prevents cable burning and equipment damage caused by current abnormality
• Modular plug‑in structure facilitates on‑site replacement and maintenance work
• High anti‑interference mechanical design adapts to harsh industrial power distribution environment
• Realize selective protection coordination in multi‑level power distribution system
• Provide reliable current fault protection for motor, transformer and heavy‑duty load circuits

Application Scenarios

• Industrial plant low‑voltage power distribution cabinet with VL400 circuit breaker
• Petrochemical, chemical plant main and branch power supply protection racks
• Thermal power plant auxiliary equipment power distribution protection units
• Metallurgy, cement and heavy‑industry large‑current load protection systems
• Water‑treatment plant and energy station power distribution electrical cabinets
• Large‑size motor and transformer feed‑out circuit protection applications
• Power distribution system renovation, trip‑unit replacement and upgrade projects
• Siemens 3VL series breaker spare‑parts inventory and on‑site maintenance projects