ABB Z-NTS neutral wire circuit breaker

ABB Z-NTS neutral wire circuit breaker

Core positioning and design philosophy of the product

The ABB Z-NTS series neutral line circuit breaker is an overcurrent protection device designed specifically for neutral lines in low-voltage distribution systems. It is mainly used to quickly and reliably cut off fault currents in the event of overload, short circuit, or grounding faults in the neutral line, avoiding equipment damage or safety accidents caused by neutral line burnout, voltage offset, and other issues. Compared with conventional circuit breakers, the Z-NTS neutral line circuit breaker has been specially optimized for the current characteristics of the neutral line. Its protection curve highly matches the fault current law of the neutral line, and can accurately identify abnormal currents in the neutral line and trigger protection actions, filling the weak link in neutral line protection in traditional distribution systems.

This series of products follows the IEC 60947 series international standards and national standards such as GB 10963.1, adopting a modular design concept. Not only is the structure compact and easy to install, but it can also seamlessly cooperate with ABB's other low-voltage electrical products (such as molded case circuit breakers and leakage protectors) to build a complete distribution protection system and meet the neutral line protection needs of distribution systems of different scales.

Core functional features and technological advantages

1. Accurate neutral line fault protection

The Z-NTS neutral line circuit breaker has dual core functions of overload protection and short-circuit protection. Its built-in bimetallic overload release and electromagnetic short-circuit release can respond accurately to different types of fault currents. When an overload current occurs in the neutral line, the bimetallic strip triggers a tripping action due to heating deformation, and the action time has an inverse time limit characteristic with the overload current. This not only avoids misoperation caused by instantaneous overload, but also reliably cuts off the circuit in case of continuous overload; When a short circuit fault occurs, the electromagnetic release instantly operates under the strong short-circuit current magnetic field, with a breaking time as low as tens of milliseconds, quickly cutting off the fault circuit and minimizing the expansion of the fault range.

2. High resolution and safety performance

The product adopts advanced arc extinguishing structure design, and the arc extinguishing chamber is filled with high-performance arc extinguishing medium, which can effectively extinguish the arc generated during fault breaking. The breaking capacity can reach up to 100kA (depending on the specific model), and can adapt to the requirements of different short-circuit levels of distribution systems. At the same time, the circuit breaker housing is made of high-strength impact resistant insulation material, which has excellent electrical insulation performance and flame resistance, and can effectively prevent phase to phase short circuits or personal electric shock risks caused by arc leakage, ensuring the safe operation of the distribution system.

3. Flexible adaptation and installation features

The Z-NTS series neutral wire circuit breaker covers a variety of current specifications (ranging from 16A to 250A), and can be flexibly selected according to the design current of the neutral wire in the distribution system. The product adopts a standard 35mm DIN rail installation method, and the installation direction can be arranged vertically or horizontally to adapt to different distribution box layout requirements; Simultaneously supporting both front and rear wiring methods, the wiring terminals adopt a crimping design with low contact resistance and excellent conductivity, which can effectively avoid terminal overheating caused by poor wiring.

4. Reliable motion stability and long-lasting design

The key components inside the circuit breaker are processed with high-precision technology and high-quality materials. For example, the bimetallic strip is made of fatigue resistant alloy material, and the electromagnetic release uses a high permeability iron core to ensure the stability and consistency of the protective action. The product has undergone strict mechanical and electrical life testing, with a mechanical life of over 10000 times and an electrical life of over 1000 times. It can meet the needs of long-term frequent operation scenarios and reduce maintenance and replacement costs in the later stage.

5. Clear status indication and convenient operation and maintenance

The circuit breaker is equipped with an intuitive action status indicator device, which can clearly distinguish the three states of "closed", "open" and "tripped" through different colored indicator lights or mechanical indicators, making it easy for operation and maintenance personnel to quickly determine the working status of the circuit breaker. Some models also support auxiliary contact expansion, which can upload the action status signal of the circuit breaker to the monitoring system to achieve remote status monitoring and improve the intelligent operation and maintenance level of the distribution system.

Key technical parameters

Basic Parameters

Rated voltage (Ue)

230V/400V AC (three-phase four wire system)

Rated current (In)

16A、20A、25A、32A、40A、50A、63A、80A、100A、125A、160A、200A、250A

polar number

1-pole (focusing on neutral wire protection)

Protection features

Overload protection feature

Compliant with IEC 60947-2 Class B curve (inverse time characteristic), no action at 1.05In, action within 2 hours at 1.3In, action within 2-10 seconds at 6In

Short circuit protection characteristics

Instantaneous tripping, tripping current is 10In-14In (adjusted according to current level), breaking time ≤ 50ms

Breaking ability (Icu)

50kA-100kA (in 400V AC system)

Withstand impulse voltage

8kV（1.2/50μs）

Mechanical and environmental parameters

mechanical life

≥ 10000 times (opening and closing operations)

Electrical life

≥ 1000 times (at rated current)

Working environment temperature

-25 ℃~70 ℃ (normal operation)

Protection level

IP20 (when installed in the distribution box)

Wiring parameters

wiring method

Front wiring/rear wiring, supporting copper and aluminum wires

Range of wire cross-section

1.5mm ² -35mm ² (adjusted according to rated current)

Applicable industries and typical application scenarios

1. Commercial buildings and residential buildings

In low-voltage distribution systems such as shopping malls, office buildings, and residential areas, the neutral wire carries three-phase unbalanced current. If overload or short circuit occurs, it can easily cause voltage deviation, leading to damage to lighting equipment, burning of household appliances, and other problems. The Z-NTS neutral line circuit breaker can be connected in series in the neutral line circuit. When the three-phase load is severely unbalanced, causing excessive neutral line current or a short circuit fault in the neutral line, the circuit breaker can quickly cut off the faulty circuit, protect downstream electrical equipment safety, and avoid fire risks caused by neutral line faults.

2. Industrial plants and production workshops

In the power distribution system of industrial production workshops, the start stop of a large number of motors, machine tools and other equipment can easily lead to three-phase current imbalance, and equipment failures may also cause neutral line short circuits. Z-NTS neutral line circuit breaker can provide reliable protection for these scenarios. For example, in the motor control circuit, when a phase motor fails and causes abnormal neutral line current, the circuit breaker will promptly cut off the neutral line to prevent the fault from spreading to other equipment, ensuring the continuous operation of the production workshop and reducing production losses caused by equipment damage.

3. Data center and communication room

The reliability requirements for power distribution systems in data centers and communication rooms are extremely high. Neutral line failures may cause power outages or damage to core equipment such as servers and switches, resulting in serious data loss and economic losses. The Z-NTS neutral line circuit breaker, with its fast breaking ability and stable operating performance, can cut off the fault current in the event of an abnormality in the neutral line, and seamlessly switch with the UPS power system to ensure the continuous power supply of core equipment and provide safety guarantees for the stable operation of data centers.

4. Medical and precision instrument venues

In hospital operating rooms, laboratories, and other places, precision medical equipment and experimental instruments have strict requirements for power supply quality. Neutral line voltage deviation may lead to decreased measurement accuracy or abnormal operation of the equipment. Z-NTS neutral line circuit breaker can effectively suppress voltage fluctuations caused by neutral line overload, and quickly isolate the fault point when the neutral line fails, avoiding affecting the normal operation of precision equipment and ensuring the accuracy of medical diagnosis and experimental work.