In the field of low-voltage terminal distribution, the reliability, safety, and intelligence level of the system are directly related to personal and property safety, as well as electrical continuity. Siemens, with its continuous innovation capability, has launched a new generation of SENTRON 5SY series low-voltage terminal distribution products, marking a comprehensive upgrade in terminal distribution technology. This series not only includes the core small circuit breaker (MCB), but also integrates residual current protection (RCD), arc fault protection (AFD), isolation switches, and a rich range of modular control products, forming a complete, efficient, and safe terminal distribution ecosystem. This article will delve into the technical core, design advantages, and extensive application value of this series of products.
Core cornerstone: Fully upgraded 5SY/5SP series miniature circuit breakers
Small circuit breakers are the "first line of defense" for terminal power distribution. The new generation SENTRON 5SY series MCB has achieved significant leaps in breaking ability, user experience, and safety design.
1. Product lineage and performance grading
This series offers a variety of choices to meet the stringent requirements of different application scenarios:
5SY6 (6000A standard type): covering a current range of 0.3A-80A, with B/C/D trip curves, suitable for most conventional buildings and industrial applications, it is an economical and efficient standardized solution.
5SY4 (10000A high-resolution type) and 5SY7 (15000A ultra-high resolution type): With higher short-circuit breaking capability, they provide stronger protection for critical loads such as data centers, medical facilities, and industrial production lines that require extremely high power continuity, effectively limiting the impact of short-circuit energy on systems and equipment.
5SY5 (10000A DC type): specially designed for DC distribution systems, such as photovoltaic power generation, energy storage systems, data center DC power supply, etc. The rated voltage covers 220V DC to 880V DC, and the wiring polarity is strictly specified to ensure the safety and reliability of DC disconnection.
5SP4 (10000A heavy-duty type): The rated current is extended to 80A-125A, suitable for large current circuits such as small motors and distribution lines, filling the gap of standard MCBs in the high current field.
5SY60 (6000A Compact): Adopting a super compact design with a width of 1 module (18mm), it is particularly suitable for residential socket circuits and lighting circuit distribution boxes with limited space, ensuring protection while maximizing space utilization.
2. Four core design advantages
The new generation of products is not simply about parameter improvement, but innovation rooted in user experience and security details:
Visual status indication: Innovative window design allows operators to directly observe the internal contact status - green represents disconnected, red represents connected, and the working status is clear at a glance, greatly facilitating troubleshooting and maintenance.
Comprehensive safety protection: adopting an integrated design of insulation, dust prevention, and touch resistance, while improving the durability of the product itself, fundamentally reducing the risk of electric shock during installation and operation.
Quick installation and maintenance: The unique sliding buckle design allows for quick installation or removal of circuit breakers from busbars without the need for tools, significantly improving installation and replacement efficiency. In addition, the dual terminal design supports the simultaneous connection of two wires, with optional upper and lower incoming lines, providing ample wiring space and enhancing wiring flexibility.
Humanized operating experience: The ergonomic anti slip texture handle design provides a comfortable and effortless operating feel, reducing fatigue during daily operations.
3. Rich accessory system
The 5SY series has a complete accessory ecosystem that can be assembled on the right side of the circuit breaker, greatly expanding its functionality:
Auxiliary contact (AS) and fault signal contact (FC): used to remotely transmit the switch status or fault trip signal of the circuit breaker to the control system, achieving status monitoring and alarm.
Split release (ST) and undervoltage release (UR): achieve remote electric disconnection or automatic protective disconnection in case of abnormal power supply voltage.
Overvoltage/undervoltage integrated release (OV/OU): Real time monitoring of line voltage, automatically cutting off the circuit when overvoltage or undervoltage faults occur, and automatically or manually restoring power supply after the voltage returns to normal, effectively protecting single-phase electrical equipment.
Remote control device (IC): endows circuit breakers with remote operation, signal feedback, and even automatic reclosing (ARD) functions, suitable for unmanned station buildings or occasions that require frequent remote operation.
Busbar (5ST37 series): We offer prefabricated insulated busbars in 10mm ² and 16mm ² sizes to achieve clear and fast busbar connections at the back end, saving a lot of wiring time and space inside the box.

Deepening protection: 5SM, 5SU, 5SV series residual current and arc fault protection devices
On the basis of overload and short circuit protection, the protection against personal electric shock and electrical fire is a rigid requirement of modern distribution systems.
1. Matrix of residual current protection products
Siemens provides a complete RCD solution from modular to integrated, from electromagnetic to electronic:
5SU1 (electromagnetic) and 5SU9 (electronic) RCBO: Integrating residual current protection and circuit breaker functions (1P+N width). 5SU1 adopts electromagnetic principle and has strong anti-interference ability; 5SU9 is electronic and can integrate overvoltage protection function, and provides a short delay type (about 10ms delay) to avoid misoperation during device startup. Provide AC type (sensitive only to AC) and A type (sensitive to both AC and pulsating DC), with rated residual operating currents covering 10mA (high-risk personal protection), 30mA (personal protection and fire prevention), and 300mA (pure fire prevention).
5SV9 Compact RCBO: With only 1 module width and a rated current of 32A, it is an ideal choice for residential and compact distribution boxes, and also supports A-type residual current protection.
5SM2 (electromagnetic) and 5SM9 (electronic) residual current protection modules: modular design, can be flexibly assembled on the left side of 5SY/5SP series circuit breakers, combined into a functional unit with leakage protection. The 5SM2 has a wide range of compatible currents (up to 100A), while the 5SM9 offers finer current settings and models with overvoltage protection.
5SV3/5SV4 electromagnetic residual current protection switch (RCCB): pure residual current protection function, available in 2P and 4P specifications. 5SV3 is of type A, and 5SV4 is of type AC. The 5SV3 series has evolved into short delay type (anti misoperation), selective type (achieving selective coordination between upper and lower levels), and SIGRES type (designed for harsh environments such as humidity and corrosiveness, with anti condensation patents), demonstrating extremely high professionalism.
5SV8 residual current monitoring device (RCM): does not actively cut off the circuit, but continuously monitors the residual current of the circuit, and sends an alarm signal when the value exceeds the set threshold. This is particularly suitable for critical power supply circuits that do not allow easy power outages (such as data centers and production lines), achieving early warning maintenance and improving power supply continuity.
2. Frontier Arc Fault Protection (AFDD)
Traditional MCB and RCD cannot reliably detect series or parallel arc faults, which are one of the main causes of electrical fires. The 5SM6 arc fault protection device fills this gap. It can be assembled on the left side of MCB or RCBO, identify dangerous arcs by analyzing current waveform characteristics, and trip in a timely manner. It has a rated current of 40A and integrates status indication, testing, and reset buttons, providing the highest level of fire protection solutions for residential and commercial buildings, especially for the renovation of old power lines.
Control and Expansion: 5TE, 5TL, 5TT Series Modular Switches and Control Products
The terminal distribution box is developing towards miniaturization, modularity, and functional integration, and Siemens' modular control product line perfectly fits this trend.
1. Isolation and operation devices
5TL1 isolation switch: Provides load isolation function from 32A to 125A, meets safety isolation standards, and is suitable for establishing clear disconnection points during maintenance.
5TE81/2 control switch: rated current 20A/22A, can be used to control small loads (such as lighting, low-power equipment), with indicator lights and auxiliary contact options, suitable for logic control in control cabinets.
5TE4 button switch and 5TE5 light indicator: rich color coding (in accordance with international standards) and contact form (instantaneous, self holding) to meet various signal input and status indication needs. LED lights and transparent covers can be easily maintained without the need for tool replacement.
5TEDC DC isolation switch: specially designed for DC systems such as photovoltaics, suitable for up to 1000VDC, 4-pole series use, with special arc extinguishing and magnetic blowing devices inside to ensure DC disconnection safety.
2. Relays and contactors
5TT4 conversion relay: a miniaturized universal relay used for controlling circuit signal conversion, isolation, and amplification, compatible with busbar installation.
5TT5x modular contactor: including AC control (5TT58) and AC/DC control (5TT50) series, rated current 20A-63A. Used for frequent connection/disconnection of loads such as lighting, heating, ventilation, and small motors. Some models come with manual operation knobs and "automatic/manual" selection functions for easy debugging and emergency operation. Its mechanical lifespan is up to 3 million cycles, and its reliability is excellent.
5TT55 OUPA self-healing overvoltage and undervoltage protector: in accordance with the Chinese special standard JB/T12762, independently installed at the incoming end of the distribution box. When the mains power experiences overvoltage or undervoltage due to neutral line faults or other reasons, it will automatically cut off and automatically reclose after the line returns to normal. Equipped with emergency power mode (allowing manual closing within a specific voltage range), locking function (preventing repeated tripping and impact loads), and optional self recovery mode, it has a high degree of intelligence and is an ideal protector for residential and important single-phase electrical equipment entering the household.
3. System integration accessories
5TE9 busbar: a fast connection system designed specifically for modular control products such as 5TE8, 5TE4, 5TT4, etc. It achieves busbar installation of control circuits like power circuits, greatly simplifying cabinet wiring.
5TE6 modular DIN rail socket: can be directly installed in the distribution box, providing a standard power interface for temporary power supply or equipment testing.
Global Certification and Special Applications
The sample also emphasizes the 5SJ4... HG series miniature circuit breakers and accessories that comply with UL489 standards. This series of products meets both IEC/EN and UL standards, with rated voltages covering 120/240V and 277/480V systems in the North American market, and a breaking capacity of 14kA. It provides a "one-stop" compliance solution for equipment manufacturers in China and other regions exporting to the North American market.
