Siemens 5SU9356-8CN16 Compact RCBO with Earth Leakage & Overcurrent Protection 16A 30mA 1P+N D

The Siemens 5SU9356-8CN16 is a compact Residual Current Circuit Breaker with Overcurrent Protection (RCBO) designed to provide comprehensive safety in electrical installations. This 16A, 30mA, 1P+N device integrates the functions of a miniature circuit breaker (MCB) and a residual current device (RCD) into a single, space-saving unit, offering superior protection against electric shock, fire hazards, and overloads. Its D-curve tripping characteristic makes it suitable for applications with high inrush currents, such as those involving transformers, induction furnaces, and motor loads. The Siemens 5SU9356-8CN16 ensures compliance with stringent safety standards, making it a reliable choice for residential, commercial, and industrial environments.

Product Specifications

| Feature                 | Specification                          |

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

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

| Manufacturer            | Siemens                                |

| Model Number            | 5SU9356-8CN16                          |

| Rated Current (In)      | 16 A                                   |

| Residual Current (IΔn)  | 30 mA                                  |

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

| Tripping Characteristic | D-Curve                                |

| Rated Voltage (Un)      | 230/240 V AC                           |

| Breaking Capacity (Icn) | 6 kA                                   |

| Frequency               | 50/60 Hz                               |

| Protection Type         | Overcurrent, Short-circuit, Earth Leakage |

| Terminal Type           | Screw Terminal                         |

| Mounting Type           | DIN Rail                               |

| Ambient Temperature     | -25°C to +45°C                         |

| Protection Class        | IP20                                   |

Core Features & Market Positioning

The Siemens 5SU9356-8CN16 distinguishes itself through its robust construction and advanced safety features. Its compact design is a significant advantage, allowing for increased panel space and easier installation, a key differentiator in crowded electrical enclosures. The integration of both overcurrent and earth leakage protection into a single unit streamlines system design and reduces component count, offering a cost-effective solution without compromising on safety. The D-curve tripping characteristic is particularly valuable for industrial applications where machinery can generate significant inductive or capacitive loads, preventing nuisance tripping while maintaining sensitive protection against dangerous earth faults. Siemens' reputation for quality and reliability further solidifies the 5SU9356-8CN16's position as a premium protective device in the market.

Key Application Scenarios

This Siemens RCBO is ideally suited for a wide array of applications requiring enhanced electrical safety and reliable circuit protection. In residential settings, it provides essential protection against electric shocks and overloads for circuits powering appliances with high startup currents, such as refrigerators or air conditioners. For commercial buildings, the 5SU9356-8CN16 is an excellent choice for protecting lighting circuits, power distribution boards, and dedicated circuits for heavy-duty equipment. In industrial environments, its D-curve characteristic makes it perfect for safeguarding circuits connected to motors, pumps, transformers, and other inductive loads, ensuring operational continuity while maintaining a high level of safety against earth faults and overcurrents.

Practical System Integration Guidance

Integrating the Siemens 5SU9356-8CN16 into electrical systems is straightforward, owing to its standard DIN rail mounting and screw terminal connections. For installation, ensure the main power supply is de-energized. Connect the line conductor to the designated input terminal and the neutral conductor to its corresponding input terminal. The load conductors are then connected to the output terminals. A key consideration for proper function is ensuring the neutral conductor is always connected to the RCBO; it must not be switched by the device itself but connected directly to the load side. Incorrect wiring, particularly regarding the neutral connection or bypassing the device, will compromise its protective capabilities. Always adhere to local electrical codes and regulations during installation.

Operation and Risk Mitigation

The Siemens 5SU9356-8CN16 operates by continuously monitoring the current flowing through the line and neutral conductors. If an imbalance occurs, indicative of an earth leakage fault (e.g., current flowing to earth through a person), the device trips and disconnects the circuit within milliseconds. Similarly, it protects against overcurrents caused by overloads or short circuits, tripping to prevent damage to equipment and wiring. To mitigate risks, regularly test the RCBO's functionality using the integrated test button; this should be performed periodically as per safety guidelines. Avoid overloading circuits beyond the 16A rating. Should nuisance tripping occur, investigate the load characteristics for excessive inrush currents or potential earth leakage paths before assuming a faulty device.

Scalability & Long-Term Value

The Siemens 5SU9356-8CN16 offers excellent long-term value due to its compatibility with the broader Siemens SENTRON system and its inherent reliability. While this specific model is a compact, integrated unit, scalability in terms of protection levels or types can be achieved by using multiple RCBOs or other devices within the SENTRON range for different circuits. Its robust design ensures a long service life, minimizing the need for frequent replacements. For facilities looking to enhance their digital capabilities, integration with Siemens' industrial automation and control systems can allow for remote monitoring of circuit status, though this specific RCBO unit does not have direct digital communication capabilities. Its core value lies in providing dependable, foundational safety for electrical circuits.

Frequently Asked Questions

What is the tripping current for the Siemens 5SU9356-8CN16?

The residual current tripping sensitivity for this RCBO is set at 30mA. This ensures rapid disconnection in case of dangerous earth leakage, protecting against severe electric shocks.

This sensitivity level is crucial for personal safety in most residential and commercial applications. It meets regulatory requirements for protecting against direct and indirect contact.

The 30mA rating signifies that when the difference between current in the line and neutral conductors exceeds 30 milliamperes, the device will trip.

Can the Siemens 5SU9356-8CN16 be used for motor protection?

Yes, the D-curve characteristic of the 5SU9356-8CN16 is specifically designed for circuits with high inrush currents, such as those powering motors. It prevents nuisance tripping during motor startup.

However, for large motors, a dedicated motor protection circuit breaker (MPCB) with adjustable overload settings and thermal/magnetic tripping might be more appropriate. This RCBO offers general overcurrent and earth leakage protection.

Always consult the motor's datasheet and relevant electrical codes to ensure this RCBO's 16A rating and D-curve are suitable for the specific motor application.

How do I test the functionality of the Siemens 5SU9356-8CN16 RCBO?

Locate the test button, typically labeled "T" or "TEST", on the front of the RCBO. Ensure the circuit is energized and a load is connected.

Press the test button firmly. The toggle lever should trip, indicating the device is functioning correctly by disconnecting the circuit.

Perform this test regularly (e.g., monthly) to verify the residual current tripping mechanism. If it does not trip, the RCBO may be faulty and requires replacement.