Siemens 5SU9356-1KK40 High Current RCBO 40A 30mA 1P+N C

The Siemens 5SU9356-1KK40 is a high-current Residual Current Circuit Breaker with Overcurrent protection (RCBO) engineered for robust electrical safety and reliable circuit management in demanding industrial and commercial environments. This 40A, 30mA, 1-pole + neutral unit offers a critical combination of overcurrent and earth leakage protection in a single, compact device, simplifying installations and reducing panel space. Its advanced tripping characteristics and high breaking capacity ensure superior protection against electrical fires, shocks, and equipment damage.

Siemens 5SU9356-1KK40: Product Specifications

| Parameter                     | Value                                         |

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

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

| Model Number                  | 5SU9356-1KK40                                 |

| Rated Current (In)            | 40A                                           |

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

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

| Tripping Characteristic       | Type C                                        |

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

| Rated Breaking Capacity (Icn) | 6 kA                                          |

| Frequency                     | 50/60 Hz                                      |

| Degree of Protection          | IP20 (enclosure), IP40 (terminal)             |

| Mounting Type                 | DIN rail                                      |

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

| Compliance Standards          | IEC/EN 61009-1, IEC/EN 61009-2-1              |

Core Features & Market Positioning

The Siemens 5SU9356-1KK40 distinguishes itself through its seamless integration of Residual Current (RC) and Overcurrent (OC) protection, a critical advantage for system designers and installers seeking to optimize panel real estate and streamline wiring. Its Type C tripping characteristic is specifically designed to accommodate inrush currents associated with inductive loads, common in industrial machinery, without nuisance tripping. This offers a significant competitive edge over simpler Residual Current Devices (RCDs) or Overcurrent Protection Devices (OCPDs) by providing comprehensive protection in a single unit. The device's robust construction and adherence to stringent international standards, such as IEC/EN 61009, position it as a reliable and high-performance solution for critical infrastructure and demanding industrial applications where safety and uptime are paramount. Siemens' reputation for quality and innovation further underpins its market appeal.

Key Application Scenarios

This high-current RCBO is exceptionally well-suited for protecting circuits in environments with significant inductive loads or where higher current ratings are necessary. Common applications include power distribution boards for industrial machinery, workshops, commercial kitchens, and large retail spaces. It is ideal for safeguarding circuits feeding motors, transformers, and lighting systems that may experience temporary high inrush currents during startup. The 30mA sensitivity ensures effective protection against indirect contact for personnel, a crucial requirement in many industrial settings. Its application extends to protecting downstream equipment from both overload and short-circuit conditions, as well as providing essential earth-fault protection, making it a versatile component for a wide array of electrical installations.

Practical System Integration Guidance

Integrating the Siemens 5SU9356-1KK40 into existing or new electrical systems is straightforward due to its standard DIN rail mounting and familiar terminal layout. For installation, ensure the main power supply is de-energized. Connect the line conductors to the appropriate input terminals and the load conductors to the output terminals. The neutral conductor must be connected to its dedicated terminal to ensure proper functioning of the residual current sensing mechanism. Wiring should comply with local electrical codes and standards, utilizing appropriately sized conductors for the 40A rating. Proper grounding of the overall system is essential for the effective operation of the RCBO's earth leakage protection. Commissioning involves a functional test by pressing the "T" (Test) button on the device, which should immediately trip the breaker, simulating an earth fault. Always ensure that the test button is pressed periodically as per manufacturer recommendations to verify the device's integrity.

Operation and Risk Mitigation

The Siemens 5SU9356-1KK40 operates by continuously monitoring the balance of current flowing through the live and neutral conductors. Should an imbalance exceeding 30mA occur – indicative of current leaking to earth, potentially through a person – the RCBO will rapidly trip, interrupting the circuit and mitigating the risk of electric shock and fire. In parallel, it protects against overcurrent conditions, including overloads and short circuits, by means of its integrated thermal and magnetic tripping mechanisms. For instance, sustained overloads will cause a thermal trip, while severe short circuits will trigger a rapid magnetic trip. Risk mitigation is inherent in its design; however, regular testing via the integrated test button is crucial. Fault identification typically involves observing the position of the toggle. If tripped, it indicates an overcurrent or earth leakage fault. Troubleshooting requires isolating the circuit, identifying the cause of the fault (e.g., damaged insulation, faulty appliance), rectifying it, and then resetting the RCBO.

Scalability & Long-Term Value

The Siemens 5SU9356-1KK40 offers significant long-term value through its compatibility with the broader Siemens SENTRON system portfolio. This allows for seamless integration into larger electrical distribution systems and offers a clear upgrade path for enhanced protection or monitoring capabilities. While this specific model is a standalone protection device, its modular design aligns with Siemens' commitment to intelligent electrical infrastructure. In applications where advanced diagnostics or remote monitoring are required, this RCBO can be part of a larger system that incorporates smart meters, energy monitoring relays, and communication modules, paving the way for IIoT integration and predictive maintenance strategies. Its robust construction ensures a long operational lifespan, reducing the total cost of ownership.

Frequently Asked Questions

What is the primary function of the Siemens 5SU9356-1KK40?

The primary function of the Siemens 5SU9356-1KK40 is to provide simultaneous protection against overcurrents (overloads and short circuits) and earth leakage currents. This dual protection capability is crucial for enhancing electrical safety in various installations. It acts as a single-pole, neutral-carrying circuit breaker with integrated residual current detection.

This device ensures personnel safety by quickly disconnecting power when a dangerous leakage current, often caused by faulty wiring or accidental contact, is detected. It also safeguards equipment and prevents electrical fires by interrupting circuits experiencing excessive current flow, whether due to overloads or short circuits. The 40A rating makes it suitable for circuits requiring robust protection.

Its comprehensive protection in a single unit simplifies panel design, installation, and maintenance, offering a cost-effective and space-saving solution compared to using separate overcurrent and residual current devices. The 30mA sensitivity is standard for personnel protection against electric shock.

How does the 30mA sensitivity of the 5SU9356-1KK40 protect against electric shock?

The 30mA residual current sensitivity is a critical safety feature designed to protect individuals from dangerous electric shocks. When current leaks from a live conductor to earth, potentially through a person, it creates an imbalance between the current flowing in the live and neutral wires. The RCBO detects this imbalance, and if it exceeds the 30mA threshold, it rapidly trips the circuit.

This rapid disconnection is vital because even a relatively small leakage current can be lethal if sustained. A trip time of milliseconds ensures that the duration of current flow through the body is minimized, significantly reducing the risk of severe injury, cardiac arrest, or burns. This level of protection is often mandated by electrical safety regulations for circuits accessible to people.

The 30mA rating is specifically chosen as it is generally considered the maximum current a human can withstand for a short period without serious harm. Therefore, the Siemens 5SU9356-1KK40 provides a vital layer of safety for occupants in residential, commercial, and industrial environments.

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

The "C" in the Type C tripping characteristic of the Siemens 5SU9356-1KK40 refers to its response to inrush currents, particularly those from inductive loads. Type C breakers are designed to tolerate higher instantaneous currents without tripping, compared to Type B breakers, but will still trip on short circuits. This characteristic is essential for applications where equipment might draw a temporary surge of current upon startup.

Specifically, a Type C device will typically trip when the current reaches between 5 to 10 times its rated current (40A in this case). This range allows for the brief, high inrush currents often produced by motors, transformers, and certain lighting ballasts, preventing nuisance tripping during normal operation. Without this capability, such circuits would frequently trip, disrupting operations.

Therefore, the Type C characteristic makes the Siemens 5SU9356-1KK40 ideal for industrial and commercial settings where these types of inductive loads are common. It balances robust protection against short circuits with tolerance for the temporary, higher currents associated with starting up machinery, ensuring operational reliability.