Siemens 5SY4340-7 40A 3-Pole 400 V Circuit Breaker

Siemens 5SY4340-7 is a 40 A, 3-pole, 400 V circuit breaker designed for robust protection of three-phase electrical circuits. Built to integrate with Siemens distribution systems, this unit carries the part number 5SY4340-7 and is ready to drop into compatible panels and switchgear.

What it does

As a three-pole circuit breaker, it interrupts all three live conductors simultaneously, ensuring balanced protection across the three phases in commercial and industrial settings. With a 400 V rating, it is suitable for typical European and many global three-phase installations that operate at 400 V line-to-line.

Key specifications

• Current rating: 40 A
• Poles: 3
• Voltage rating: 400 V
• Part number: 5SY4340-7

Why choose this Siemens breaker?

Reliability and consistency come standard when you choose a Siemens 5SY series device. This breaker is designed to fit Siemens-compatible enclosures and distribution boards, helping you maintain a clean, organized protection scheme. It supports safe, predictable tripping behavior in the event of overloads or short circuits on a 3-phase circuit, reducing risk of damage to motors, pumps, and control equipment.

Use cases and applications

• Three-phase feeders in industrial panels, machine rooms, and commercial electrical rooms
• Protection for motors and equipment powered from 400 V three-phase systems
• Replacement or upgrade of existing 3-pole protections in Siemens panel lines

Tips for installation and maintenance

• Ensure panel compatibility: verify mounting style and busbar connection in your Siemens distribution board.
• Label the circuit clearly with the 5SY4340-7 part number for future maintenance and audits.
• Keep spare 5SY4340-7 units on hand to minimize downtime during replacements in critical systems.