Siemens 5SU9356-7KK25 Double Pole Protection RCBO 25A 30mA 1P+N C

The Siemens 5SU9356-7KK25 is a high-performance Double Pole Protection Residual Current Circuit Breaker with Overcurrent protection (RCBO), engineered for superior electrical safety and operational reliability in demanding industrial environments. This unit, rated at 25A with a sensitivity of 30mA and a 1P+N configuration, integrates residual current and overcurrent protection into a single, space-saving device, significantly simplifying panel design and installation. Its advanced tripping characteristics and robust construction ensure maximum protection against electric shock, fire hazards, and equipment damage, making it an indispensable component for modern electrical installations seeking robust safety and compliance.

Product Specifications

| Feature                       | Specification                                     |

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

| Product Type                  | Double Pole Protection RCBO                       |

| Siemens Model Number          | 5SU9356-7KK25                                     |

| Rated Current (In)            | 25A                                               |

| Residual Current Sensitivity  | 30mA                                              |

| Pole Configuration            | 1 Pole + Neutral (1P+N)                           |

| Tripping Characteristic       | Type C                                            |

| Breaking Capacity (Icn)       | 6 kA                                              |

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

| Frequency                     | 50/60 Hz                                          |

| Protection Class              | IP20 (Device), IP40 (Enclosure)                   |

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

| Mounting Type                 | DIN Rail (35mm)                                   |

| Compliance Standards          | IEC 61009-1, IEC 60898-1, EN 61009-1, EN 60898-1 |

Core Features & Market Positioning

The Siemens 5SU9356-7KK25 RCBO distinguishes itself through its dual-functionality, combining the protective attributes of a Miniature Circuit Breaker (MCB) and a Residual Current Device (RCD) in one compact unit. This integration offers significant advantages over separate devices, reducing wiring complexity, saving valuable panel space, and lowering installation costs. The Type C tripping curve is specifically designed to handle moderate inrush currents characteristic of inductive loads, such as motors and transformers, without causing nuisance tripping, thereby enhancing operational continuity. Furthermore, its 30mA sensitivity provides essential protection against indirect contact, a critical safety requirement in numerous industrial and commercial applications. Siemens' reputation for manufacturing high-quality, reliable electrical components underpins the market positioning of this RCBO as a trusted solution for safety-critical circuits.

Key Application Scenarios

This Siemens 5SU9356-7KK25 RCBO is ideally suited for protecting individual circuits in a wide array of industrial settings. Its robust design and 6 kA breaking capacity make it suitable for distribution boards in manufacturing plants, process control systems, and heavy machinery environments where reliable protection against overcurrents and residual currents is paramount. It is frequently deployed to safeguard circuits supplying motors, pumps, HVAC systems, and other inductive equipment that may experience transient current surges. In commercial buildings, it provides essential safety for lighting circuits, socket outlets, and dedicated equipment power supplies, ensuring compliance with electrical safety regulations and mitigating risks of electric shock and fire.

Practical System Integration Guidance

Integrating the Siemens 5SU9356-7KK25 into existing or new electrical systems is straightforward due to its standard DIN rail mounting and clear terminal configurations. For installation, ensure the main power supply is de-energized. The line conductor (live) should be connected to the designated terminal marked 'L', and the neutral conductor to the terminal marked 'N' on the RCBO's input side. The outgoing protected circuit's live conductor connects to the 'L' output terminal, and its neutral conductor to the 'N' output terminal. For accurate residual current detection, it is imperative that both the live and neutral conductors of the protected circuit pass through the RCBO.

Correct wiring is crucial for the proper functioning of the 5SU9356-7KK25. Ensure all connections are tight and comply with local electrical codes and standards. The device is designed for single-phase, two-wire (1P+N) systems. When installing multiple RCBOs, maintain adequate spacing for ventilation and ease of access. Always verify that the circuit breaker's rated current (25A) and breaking capacity (6kA) are appropriate for the protected load and the overall system's fault current level. A test button is typically integrated for periodic functional checks of the residual current tripping mechanism.

Commissioning involves energizing the circuit and then operating the test button to confirm that the RCBO trips correctly. This verifies the integrity of both the residual current detection and the tripping mechanism. If the RCBO fails to trip during the test, it indicates a malfunction, and the device should be immediately replaced. Post-installation, clear labeling of the RCBO's function and protected circuit is essential for future maintenance and troubleshooting.

Operation and Risk Mitigation

The Siemens 5SU9356-7KK25 operates by continuously monitoring the balance of current flowing in the live and neutral conductors. If an imbalance occurs—indicating that current is leaking to earth, often through a person or faulty insulation—the RCBO detects this differential current. When the leakage current exceeds the 30mA threshold, it triggers an internal mechanism that rapidly disconnects both the live and neutral conductors from the power supply, thereby preventing electric shock and potential fires. The Type C characteristic ensures that it allows for normal operation with loads that have a higher inrush current without tripping prematurely.

Risk mitigation with this RCBO is primarily achieved through its core protective functions. It significantly reduces the danger of electric shock by rapidly interrupting power in case of earth faults. It also prevents fires that could be initiated by persistent low-level earth leakage currents or overcurrents that generate excessive heat in wiring. Regular testing of the RCBO using its integrated test button is a vital part of operational risk mitigation, ensuring the device remains functional over its service life.

While specific fault codes are not typically associated with RCBOs, the primary indicators of an issue would be the device tripping unexpectedly or failing to trip when it should. If the 5SU9356-7KK25 trips repeatedly, it signals an persistent earth leakage or overload condition in the protected circuit, requiring thorough investigation of the connected equipment and wiring. If it fails to trip during a manual test, it indicates a critical failure of the residual current detection or tripping mechanism, necessitating immediate replacement of the unit to maintain safety standards.

Scalability & Long-Term Value

The Siemens 5SU9356-7KK25 offers excellent long-term value through its compatibility with the broader Siemens industrial automation ecosystem and its adherence to international standards. This ensures that it can be seamlessly integrated into existing electrical infrastructure and easily specified for future projects. Its robust build quality and the reputation of Siemens for durable components translate to a long operational lifespan, minimizing the need for premature replacement and reducing total cost of ownership.

For facilities looking to enhance their electrical safety and monitoring capabilities, this RCBO serves as a foundational element. While not inherently a smart device, its reliable performance contributes to overall system stability, which is a prerequisite for advanced digital solutions. In systems employing smart meters or energy management systems, the predictable and safe operation of individual circuits protected by such RCBOs provides valuable data integrity.

The scalability aspect also lies in its modularity within distribution boards. As power demands change or new circuits are added, additional 5SU9356-7KK25 units can be installed adjacent to existing ones, provided the main distribution board has sufficient capacity and busbar compatibility. This allows electrical systems to evolve while maintaining consistent levels of safety and protection across all protected circuits.

FAQs

What is the primary function of the Siemens 5SU9356-7KK25?

The Siemens 5SU9356-7KK25 acts as a dual-purpose protective device. It combines overcurrent protection, preventing damage from excessive electrical loads. It also provides residual current protection, safeguarding against dangerous electric shocks.

This RCBO is designed to detect imbalances in electrical current flow. Such imbalances typically indicate current leakage to earth. This leakage can occur through faulty wiring or accidental human contact.

Upon detecting a dangerous level of residual current (30mA), it rapidly disconnects the power supply. This significantly reduces the risk of electrocution and fires caused by electrical faults.

What does the "C" in Type C tripping characteristic mean for this RCBO?

The "C" designation refers to the RCBO's tripping curve for overcurrent faults. This specific curve is designed to tolerate higher inrush currents. These are common with inductive loads like motors and transformers.

A Type C breaker will not trip for moderate current surges up to a certain multiple of its rated current. This prevents nuisance tripping during normal equipment startup. It ensures operational continuity for industrial machinery.

However, it will still trip quickly for short-circuit conditions. This provides essential protection against severe fault events while accommodating typical operational demands.

How does the 30mA sensitivity of the 5SU9356-7KK25 enhance safety?

A 30mA residual current sensitivity is considered the threshold for protecting individuals from dangerous electric shock. This level of sensitivity is crucial for preventing serious injury or fatality. It is a standard requirement for many circuits, especially those in potentially damp environments.

When current leaks to earth and exceeds this 30mA limit, the RCBO trips almost instantaneously. This rapid disconnection is vital, as even a small amount of current can be harmful if prolonged. It ensures that protective measures are highly effective.

This sensitivity is specifically designed for indirect contact protection. It complements the direct contact protection offered by the overcurrent function. It provides comprehensive safety against electrical hazards.

Can the Siemens 5SU9356-7KK25 be used in residential applications?

While primarily designed for industrial use, the 5SU9356-7KK25 can be suitable for certain residential circuits. Its 30mA sensitivity is ideal for protecting circuits such as those supplying bathrooms, kitchens, or outdoor outlets. These areas have a higher risk of water-related electrical hazards.

However, residential electrical codes and practices often specify different types of RCDs or RCBOs. It is essential to consult local building and electrical regulations. These will dictate the precise requirements for residential installations.

For standard residential circuits like general lighting and outlets, a more common 10mA or 30mA RCD might be specified. However, the 25A rating and Type C characteristic may be appropriate for specific higher-demand residential circuits if needed.

What is the breaking capacity (kA) of this RCBO, and why is it important?

The Siemens 5SU9356-7KK25 has a breaking capacity of 6 kA. This rating indicates the maximum fault current the RCBO can safely interrupt without sustaining damage. It is a critical safety parameter for any circuit protection device.

A higher breaking capacity is essential in industrial settings. These environments often have lower impedance electrical systems. This can lead to significantly higher potential fault currents.

Ensuring the RCBO's breaking capacity exceeds the prospective fault current at its installation point is vital. This prevents catastrophic failure of the device during a severe short circuit. It protects both the equipment and personnel.

What is the difference between an RCD and an RCBO like the 5SU9356-7KK25?

An RCD (Residual Current Device) primarily provides protection against electric shock by detecting earth leakage currents. It does not offer protection against overcurrents (overloads or short circuits). An RCD needs to be paired with an MCB for complete circuit protection.

An RCBO (Residual Current Circuit Breaker with Overcurrent protection) integrates both functions into a single device. It combines an RCD and an MCB. This provides both earth leakage protection and overcurrent protection in one unit.

The 5SU9356-7KK25 is an RCBO, meaning it offers a comprehensive solution for circuit safety. This reduces panel space, wiring complexity, and installation time compared to using separate RCD and MCB devices.

Is the 5SU9356-7KK25 suitable for protecting motor circuits?

Yes, the Siemens 5SU9356-7KK25 is suitable for protecting motor circuits, particularly due to its Type C tripping characteristic. Motor startup typically draws a higher temporary current (inrush current) than the motor's normal running current. The Type C curve is designed to withstand these momentary surges without tripping.

This characteristic ensures that the motor can start up reliably. It prevents unnecessary interruptions to industrial processes. The RCBO will still provide essential protection against sustained overloads and dangerous earth leakage faults.

When selecting an RCBO for a motor, it's crucial to match the rated current (25A) to the motor's full load current. Also, consider the specific starting characteristics and potential fault levels of the installation.

How is the Siemens 5SU9356-7KK25 installed in a control panel?

Installation involves mounting the RCBO onto a standard 35mm DIN rail within the control panel. Ensure the panel is de-energized before beginning installation. The live and neutral conductors of the incoming power supply are connected to the input terminals of the RCBO.

The outgoing conductors for the circuit being protected are then connected to the output terminals of the RCBO. It is crucial that both live and neutral conductors pass through the device for residual current detection to function correctly. Ensure all connections are secure and follow wiring best practices and local electrical codes.

After wiring, a test of the residual current function should be performed using the integrated test button. This confirms proper operation before the panel is put into service. Proper labeling of the protected circuit is also recommended.

What are the advantages of using a double pole RCBO like this model?

A double pole RCBO, such as the 5SU9356-7KK25, disconnects both the live and neutral conductors simultaneously. This provides a more complete isolation from the power supply compared to single pole devices. This is often a requirement in certain electrical codes and standards for enhanced safety.

Simultaneous switching of both poles ensures that the neutral conductor cannot become live when the circuit is switched off. This is particularly important in systems where the neutral conductor may carry current or be referenced to earth. It prevents dangerous situations that could arise from partial disconnection.

This design is crucial for maintaining system integrity and ensuring effective isolation for maintenance. It adheres to stricter safety protocols, making it a preferred choice for critical industrial applications.

Does Siemens offer warranty or support for the 5SU9356-7KK25?

Siemens generally provides a manufacturer's warranty for its electrical components, including RCBOs like the 5SU9356-7KK25. The specific duration and terms of the warranty can vary depending on the region and the distributor. It is advisable to check the warranty documentation provided at the time of purchase.

Siemens also offers extensive technical support for its products. This can include access to technical documentation, datasheets, application guides, and customer service hotlines. Their support network is designed to assist users with product selection, installation, troubleshooting, and compliance queries.

For detailed warranty information and technical support, customers should contact their authorized Siemens distributor or Siemens' regional sales and service representatives. They can provide the most accurate and up-to-date assistance.