Siemens 5SU9356-2CN40 RCBO Earth Leakage & Overload Protector 40A 30mA 1P+N D

The Siemens 5SU9356-2CN40 RCBO is a highly reliable and compact Residual Current Circuit Breaker with Overcurrent protection, designed for safeguarding electrical installations against earth leakage faults and overloads. This 40A, 30mA, 1P+N device offers robust protection for residential, commercial, and light industrial applications, ensuring personnel safety and equipment integrity. Its advanced tripping characteristics and high breaking capacity make it a superior choice for critical power distribution points.

Product Specifications

| Feature                   | Specification                               |

| :------------------------ | :------------------------------------------ |

| Product Type              | RCBO (Residual Current Circuit Breaker with Overcurrent protection) |

| Manufacturer              | Siemens                                     |

| Model Number              | 5SU9356-2CN40                               |

| Rated Current (In)        | 40A                                         |

| Rated Residual Operating Current (IΔn) | 30mA                                        |

| Number of Poles           | 1P+N (1 Pole + Neutral)                     |

| Tripping Characteristic   | Type D                                      |

| Rated Voltage (Ue)        | 230/400V AC                                 |

| Breaking Capacity (Icn)   | 6kA                                         |

| Frequency                 | 50/60 Hz                                    |

| Terminal Type             | Screw Terminals                             |

| Mounting Type             | DIN Rail                                    |

| Environmental Protection  | IP20                                        |

Core Features & Market Positioning

The Siemens 5SU9356-2CN40 distinguishes itself through its dual-functionality, combining earth leakage and overload protection in a single, space-saving unit. This integration significantly simplifies panel design and installation, reducing material and labor costs. Its Type D tripping curve provides enhanced protection against inrush currents common in inductive loads, such as motors and transformers, without causing nuisance tripping. This makes the 5SU9356-2CN40 ideal for applications where high starting currents are expected, a crucial differentiator in the competitive RCBO market. Siemens' reputation for quality and reliability further solidifies its market position as a trusted solution for demanding electrical environments.

Key Application Scenarios

This RCBO is exceptionally well-suited for protecting circuits in residential buildings, particularly for high-demand areas like kitchens and workshops where inductive loads are prevalent. In commercial settings, it serves effectively in sub-distribution boards for lighting, power outlets, and HVAC systems, ensuring compliance with safety standards. For light industrial use, the 5SU9356-2CN40 is a practical choice for safeguarding individual machine circuits or workstations, offering reliable protection against both electrical faults and operational overloads. Its 30mA sensitivity is optimal for personal protection against electric shock, a fundamental requirement across all these sectors.

Practical System Integration Guidance

Integrating the Siemens 5SU9356-2CN40 into an electrical system is straightforward due to its standard DIN rail mounting and clear terminal markings. The incoming power supply should be connected to the line terminals, and the outgoing load to the respective load terminals, ensuring the neutral conductor is correctly terminated in the neutral terminal. For optimal performance and safety, it is crucial to ensure the main earthing system is properly installed and bonded. The Type D characteristic is particularly beneficial when protecting circuits feeding motors; ensure the motor's nominal current and starting current requirements are within the RCBO's 40A rating and its D-curve's tripping range. Always adhere to local electrical codes and standards during installation.

Operation and Risk Mitigation

The 5SU9356-2CN40 operates by continuously monitoring the current flowing through the live and neutral conductors. If an imbalance occurs, indicating a current leak to earth exceeding the 30mA threshold, the RCBO will trip, disconnecting the circuit. Similarly, if the current exceeds the 40A overload limit for a specified duration, or if a short circuit occurs, the overcurrent protection element will activate. To mitigate risks, regular testing of the RCBO's functionality using its integrated test button (typically labeled 'T' or 'TEST') is recommended, usually on a monthly basis. This ensures the tripping mechanism remains responsive. Incorrect wiring or exceeding the device's rated capacity are primary causes of failure, underscoring the importance of professional installation and adherence to specifications.

Scalability & Long-Term Value

The 5SU9356-2CN40 offers excellent compatibility with Siemens' broader range of modular DIN-rail mounted electrical components, facilitating easy expansion and integration within existing or new distribution panels. This inherent compatibility ensures that as electrical system requirements evolve, the RCBO can be seamlessly incorporated into larger, more complex setups, including those potentially integrating with building management systems or smart grid technologies. Its robust construction and adherence to stringent Siemens manufacturing standards guarantee a long operational lifespan, providing enduring protection and value for the electrical installation over many years.

Frequently Asked Questions (FAQs)

What is the tripping characteristic of the Siemens 5SU9356-2CN40 RCBO?

The Siemens 5SU9356-2CN40 features a Type D tripping characteristic. This provides enhanced protection against high inrush currents associated with inductive loads, such as motors and transformers.

What applications is the Siemens 5SU9356-2CN40 best suited for?

This RCBO is ideal for circuits with inductive loads like motors. It is also excellent for applications requiring high starting currents, preventing nuisance tripping.

Does the Type D curve offer any disadvantage compared to other curves?

Type D curves offer delayed tripping for high inrush currents. This can be a disadvantage if precise, very fast tripping for smaller overloads is critical.

What is the sensitivity of the Siemens 5SU9356-2CN40 RCBO?

The Siemens 5SU9356-2CN40 RCBO has a residual operating current sensitivity of 30mA. This level is standard for personal protection against electric shock.

Is 30mA sensitivity suitable for all types of earth leakage protection?

30mA sensitivity is excellent for personal protection against direct contact. Higher sensitivities may be needed for equipment protection in some industrial settings.

Can the 5SU9356-2CN40 be used for fire protection?

While it offers earth leakage protection which can prevent arcing faults, it is not specifically certified as a fire protection device on its own. Always consult standards.

What does 1P+N mean for this RCBO?

1P+N signifies that the RCBO protects one live pole and the neutral conductor. This ensures complete disconnection of both conductors in case of a fault.

Is the neutral conductor switched by the 5SU9356-2CN40?

Yes, the neutral conductor is switched and protected by this 1P+N RCBO. This provides full isolation when a fault occurs.

How does the Siemens 5SU9356-2CN40 protect against overloads?

The device incorporates an overcurrent sensing element that detects sustained current above its 40A rating. It then trips to disconnect the circuit, preventing damage.

What is the breaking capacity of the Siemens 5SU9356-2CN40?

This RCBO has a breaking capacity of 6kA. This rating indicates its ability to safely interrupt fault currents up to this level.