Siemens 5SU1656-1KK20 Residual Current Protector (RCCB) 20A 300mA 1P+N C

The Siemens 5SU1656-1KK20 Residual Current Protector (RCCB) is a vital component for safeguarding electrical installations against earth faults. This 20A, 300mA, 1P+N device offers robust protection, acting as a crucial safety measure in residential, commercial, and industrial settings. Its core advantage lies in its ability to detect leakage currents and swiftly interrupt the circuit, preventing electric shocks and fire hazards. Key technical parameters include its rated current of 20A, residual operating current of 300mA for enhanced safety, and a 1-pole + neutral configuration, suitable for single-phase systems. The C-type tripping characteristic ensures it can handle inrush currents without nuisance tripping, making it ideal for circuits with inductive loads.

Product Specifications

| Parameter                 | Specification                               |

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

| Product Type              | Residual Current Circuit Breaker (RCCB)     |

| Manufacturer              | Siemens                                     |

| Model Number              | 5SU1656-1KK20                               |

| Rated Current (In)        | 20 A                                        |

| Residual Operating Current | 300 mA                                      |

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

| Tripping Characteristic   | Type C                                      |

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

| Frequency                 | 50/60 Hz                                    |

| Breaking Capacity (Icn)   | 6 kA                                        |

| Terminal Type             | Screw Terminals                             |

| Mounting Type             | DIN Rail                                    |

| IP Rating                 | IP20 (uninstalled), IP40 (installed in enclosure) |

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

Core Features & Market Positioning

The Siemens 5SU1656-1KK20 stands out in the protective devices market due to its combination of high reliability and advanced safety features. As a product from Siemens, a globally recognized leader in electrical engineering, it benefits from decades of innovation and stringent quality control. Its 300mA sensitivity is optimized for fire protection applications, providing an additional layer of safety beyond standard personal protection levels. The Type C tripping characteristic is a significant differentiator, offering enhanced immunity to transient overcurrents often encountered in systems with motors, transformers, or fluorescent lighting, thus reducing the likelihood of unwarranted disconnections and improving operational continuity. This positions the 5SU1656-1KK20 as a premium choice for applications demanding superior performance and reduced nuisance tripping.

Key Application Scenarios

This Siemens RCCB is ideally suited for a wide array of applications where earth leakage protection is paramount. In residential settings, it ensures the safety of occupants by protecting against indirect contact and fire hazards caused by insulation faults in circuits powering appliances, lighting, and general-purpose outlets. For commercial environments, such as offices, retail spaces, and hotels, it provides essential safety compliance and protects sensitive electronic equipment from damage due to earth faults. In industrial facilities, the 5SU1656-1KK20 is deployed in machine control circuits, power distribution panels, and areas with higher electrical load densities, where its 20A rating and Type C characteristic are particularly beneficial for managing inductive loads and ensuring uninterrupted production processes.

Practical System Integration Guidance

Integrating the Siemens 5SU1656-1KK20 into existing or new electrical systems is a straightforward process, adhering to standard electrical installation practices. The device is designed for mounting on a standard 35mm DIN rail, allowing for secure and organized installation within distribution boards or enclosures. Wiring involves connecting the phase and neutral conductors from the upstream power source to the designated input terminals, typically marked with 'L' and 'N' respectively. The output terminals, also marked 'L' and 'N', are then connected to the downstream circuit or load. It is critical to ensure that the neutral conductor is properly connected to the 'N' terminal and that the device is not overloaded beyond its 20A rating. For optimal safety and compliance, always refer to the manufacturer's installation manual and local electrical codes.

Operation and Risk Mitigation

The Siemens 5SU1656-1KK20 operates by continuously monitoring the current flowing through the phase and neutral conductors of a circuit. Under normal conditions, these currents are equal and opposite. If an earth fault occurs, a portion of the current will divert to earth, creating an imbalance. When this imbalance exceeds the residual operating current of 300mA, the RCCB's internal mechanism rapidly trips, disconnecting the power supply. This swift action is crucial for mitigating the risks of electric shock, which can cause severe injury or fatality, and for preventing electrical fires that can arise from persistent low-level leakage currents. Regular testing of the RCCB using its integrated test button is recommended to ensure its continued operational integrity and to verify its protective function.

Scalability & Long-Term Value

The Siemens 5SU1656-1KK20 offers significant long-term value through its compatibility and integration capabilities within broader Siemens electrical systems and modern digital infrastructure. As a standard DIN-rail mounted device, it seamlessly integrates with other Siemens circuit breakers, RCDs, and surge protection devices, allowing for modular and expandable electrical panels. While this specific model is primarily focused on direct fault protection, its robust design and Siemens' commitment to quality ensure a long operational lifespan. For enhanced system monitoring and advanced diagnostics, it can be part of a larger system where upstream intelligent devices or building management systems can provide data on circuit status and potential issues, contributing to predictive maintenance strategies and overall operational efficiency in IIoT environments.

Frequently Asked Questions

What is the primary function of the Siemens 5SU1656-1KK20?

This device functions as a Residual Current Circuit Breaker (RCCB). It is designed to detect and interrupt electrical circuits when it senses an imbalance in current. This imbalance typically signifies a leakage current to earth, which can cause electric shock or fire.

This safety feature is critical for protecting both people and property. It acts as a vital safeguard against indirect contact with live conductors. The 300mA sensitivity also aids in fire prevention by quickly cutting power.

Its main purpose is to disconnect the power supply rapidly when a dangerous earth fault occurs. This prevents serious injury and reduces the risk of electrical fires.

Can the Siemens 5SU1656-1KK20 be used for overload protection?

No, the Siemens 5SU1656-1KK20 is specifically designed for residual current protection only. It detects earth leakages, not overcurrents or short circuits.

For overload and short-circuit protection, it must be installed in conjunction with a miniature circuit breaker (MCB) or a fuse. This combination provides comprehensive circuit protection.

Therefore, it is essential to use this RCCB as part of a complete protective system, typically downstream of an MCB or fuse for full safety compliance.

What is the significance of the 'C' in the tripping characteristic for this RCCB?

The 'C' type tripping characteristic indicates that the breaker is designed to tolerate higher inrush currents without tripping. This is common for circuits with inductive loads.

Specifically, Type C breakers will trip between 5 to 10 times the rated current. This makes them suitable for circuits powering motors, transformers, and fluorescent lighting.

This characteristic helps to prevent nuisance tripping in applications where temporary current surges are expected, ensuring operational stability.

How does the 300mA residual current rating impact its application?

The 300mA residual current rating signifies that the RCCB will trip when it detects an earth leakage current of 300 milliamperes or more. This level is generally considered for fire protection.

While personal protection RCCBs typically have a 30mA rating, the 300mA rating is chosen for applications where the primary concern is preventing fires. This is common in industrial or commercial settings.

It provides an additional layer of safety beyond standard personal protection, focusing on mitigating fire hazards that could arise from persistent earth faults.

What type of circuits is the Siemens 5SU1656-1KK20 suitable for?

This 20A, 1P+N RCCB is suitable for single-phase circuits with a rated current of up to 20A. Its Type C characteristic makes it ideal for circuits with inductive loads.

Common applications include circuits for motors, pumps, air conditioning units, and other equipment that may experience temporary current surges upon startup. It's also widely used in distribution boards for general power circuits.

Its robust design and specific tripping characteristics ensure reliable operation in environments where standard tripping curves might lead to frequent false trips.

Is the Siemens 5SU1656-1KK20 compatible with other brands of electrical components?

While the 5SU1656-1KK20 is designed to mount on a standard 35mm DIN rail, ensuring mechanical compatibility, electrical compatibility with components from other manufacturers is not guaranteed. Siemens products are optimized to work within their own ecosystem.

For guaranteed performance, reliability, and compliance with safety standards, it is always recommended to use Siemens RCCBs with other Siemens protective devices like MCBs and RCDs. Mixing brands can sometimes lead to unexpected behavior.

However, for basic functionality, it will likely connect and operate with other standard DIN-rail mounted components, but full system integration and performance testing are advised.

What is the breaking capacity (Icn) of this RCCB?

The breaking capacity (Icn) of the Siemens 5SU1656-1KK20 is 6 kA. This refers to the maximum fault current that the device can safely interrupt without being destroyed.

A 6 kA breaking capacity is sufficient for many residential and commercial installations. It indicates the RCCB's ability to safely clear a fault current under typical network conditions.

It is crucial that the breaking capacity of the protective device is greater than the prospective fault current at the point of installation to ensure safety.

How often should the test button on the Siemens 5SU1656-1KK20 be used?

The test button should be used regularly to ensure the proper functioning of the RCCB. A common recommendation is to test it monthly.

Pressing the test button simulates an earth fault and should cause the RCCB to trip. If it does not trip, the device may be faulty and requires inspection or replacement.

This regular testing is a critical part of maintaining electrical safety and ensuring the device provides the intended protection against electric shock.

What are the implications of a "1P+N" configuration?

The "1P+N" (1 Pole + Neutral) configuration means that both the phase conductor and the neutral conductor are switched by the RCCB. This provides complete isolation of the circuit when the device trips.

In a 1P+N device, the neutral conductor is switched simultaneously with the phase conductor. This ensures that neither conductor remains live when the circuit is interrupted.

This configuration is standard for single-phase circuits to ensure that both live conductors are disconnected for maximum safety.

Where is the most appropriate installation location for this RCCB?

The Siemens 5SU1656-1KK20 is best installed in main distribution boards or sub-distribution boards. It should be located upstream of the circuits it is intended to protect.

Consider installing it in areas where inductive loads are present, such as workshops or industrial control panels, due to its Type C characteristic. It is also suitable for general power distribution in commercial and residential buildings.

Proper installation ensures that it can effectively monitor the current in the protected circuit and provide timely tripping in case of an earth fault.