Siemens Miniature circuit breaker, D, 70mm, 3-pole, 400V, 10kA, 40A Part number 5SY4340-8

Product Overview

The Siemens 5SY4340-8 is a 3-pole miniature circuit breaker (MCB) designed for industrial low-voltage distribution. It features the D-characteristic tripping curve, is rated at 40 A and supports up to 400 V AC with a breaking capacity of 10 kA, all packaged in a compact 70 mm installation depth design.

Key Features

• 3-pole design (3P) providing full three-phase protection
• Rated current: 40 A with D-characteristic trip curve—suitable for circuits with high inrush currents
• High breaking capacity: up to 10 kA at 400 V AC
• Compact depth of 70 mm, aiding installation in space-restricted distribution boards
• Part of the SENTRON 5SY4 series of circuit breakers—designed for reliable protection in industrial systems

Technical Specifications

• Product Series: Siemens SENTRON 5SY4 Miniature Circuit Breakers
• Article Number: 5SY4340-8
• Number of Poles: 3
• Tripping Characteristic: D
• Rated Current (In): 40 A
• Rated Operational Voltage: 400 V AC
• Rated Short-Circuit Breaking Capacity (Icn): 10 kA at 400 V AC
• Mounting Depth: 70 mm
• Mechanical Service Life (Typical): 10,000 operations
• Degree of Pollution: 3
• Overvoltage Category: III
• Weight (Approx.): 0.48 kg (≈ 480 g)

Compliance & Certifications

• Compliant with IEC/EN standards for miniature circuit breakers (e.g., IEC 60898-1, IEC 60947-2)
• Designed and manufactured according to Siemens standard for industrial protection devices
• RoHS compliant and suitable for global low-voltage distribution applications

Applications

The 5SY4340-8 is ideal for industrial and commercial electrical distribution boards where robust protection is required for branch circuits with high switching inrush (e.g., motor loads, transformers). Its high breaking capacity, D-curve characteristic and compact 70 mm depth make it suitable for installations where space is limited but high performance is needed.