The NM1-400S/3000 400A is a 3-pole interruttore automatico scatolato manufactured by CHINT Electric. As a standard type (S) product in the NM1 series, it has a rated current of 400A and is designed for overload, short-circuit, and undervoltage protection in power distribution systems.
- Model Designation Explanation
NM1: CHINT NM1 series molded case circuit breaker
400: Frame size rated current of 400A (the maximum current rating in this series)
S: Breaking capacity characteristic code (standard type with a breaking capacity of 50kA)
3000: Pole number + release type + accessory configuration
First digit “3”: 3-pole (three-phase) design
“000”: Indicates no accessories (no auxiliary contacts, no alarm contacts, no shunt release)
400UN: Rated operating current of 400A (the maximum current for long-term stable operation)
- Core Parameters and Performance
| Parameter Item | Valore | Description |
| Rated Insulation Voltage | 800V | Maximum withstand voltage for insulation |
| Rated Operating Voltage | 690V (AC 50Hz) | Standard voltage suitable for three-phase systems |
| Corrente nominale | 400UN | Maximum current for long-term stable operation |
| Capacità di interruzione | 50IL | Maximum short-circuit current that can be safely interrupted |
| Arc Flash Distance | ≤100mm | Arc ejection distance during short-circuit breaking |
| Release Type | Thermal-magnetic | Provides both thermal protection (sovraccarico) and magnetic protection (short-circuit) |
| Protection Functions | Overload, short-circuit, sottotensione | Comprehensive circuit protection |
| Operation Method | Manual (standard configuration) | Electric operating mechanism is optional |
| Protection Rating | IP20 | Prevents intrusion of solid foreign objects larger than 12mm |
| Mounting Method | Front/back panel wiring (optional) | Flexible installation methods |
| Peso | Approximately 6.8kg (4-pole reference) | Net weight of the product |
III. Appearance and Structural Features
Housing Material: High-strength thermoplastic with properties of impact resistance, self-extinguishing, and heat resistance
Operating Handle: Located in the center of the front face of the circuit breaker; red indicates open position, green indicates closed position
Terminal Blocks: 3 sets of input/output terminals (corresponding to three phases), equipped with M12 hexagon socket screws (coppia: 26N·m)
Dimension Reference:
– Larghezza: Approximately 128mm (3-pole)
– Height: Approximately 257mm (reference to similar products)
– Depth: Approximately 150mm (reference to similar products)
Internal Structure:
Arc Extinguishing Chamber: Adopts multi-stage arc extinguishing technology to quickly extinguish arcs and protect equipment safety
Thermal-magnetic Release: Composed of thermal elements (bimetallic strips) and electromagnetic elements (coils), which detect overload and short-circuit currents respectively
- Scenari applicativi tipici
- Industrial Power Distribution Systems:
– Main switch of power distribution boxes in factory workshops
– Power supply protection for large-scale equipment (per esempio., motori, tifosi, pompe dell'acqua)
- Commercial Buildings:
– Floor power distribution boxes in shopping malls and office buildings
– Power supply protection for large electrical equipment such as air conditioning systems and elevators
- Infrastructure Facilities:
– Power distribution systems in public buildings like hospitals and schools
– UPS output protection in data centers
- Precauzioni per l'uso
- Installation Requirements:
– Install vertically and reserve sufficient heat dissipation space (≥10cm)
– Install arc baffles (standard configuration) to prevent phase-to-phase short circuits
– Ensure the conductor cross-sectional area is ≥400mm² (for copper busbars) or ≥370mm² (for copper wires) during wiring
- Operation and Maintenance:
– Regularly check for overheating and deformation of contacts
– Clean internal dust every six months (operate after power-off)
– Periodically test protection functions with professional testing equipment
- Safety Tips:
– Inspect contact conditions after interrupting fault currents; replace if necessary
– Strictly prohibit wiring or replacement operations under load conditions
– Confirm that the circuit is completely de-energized before conducting maintenance after the circuit breaker is opened
- Optional Accessories for Function Expansion
The functions of the NM1-400S/3000 circuit breaker can be expanded by installing accessories:
| Accessory Type | Function Expansion |
| Contatti ausiliari | Provide circuit breaker status signals (open/closed) for remote monitoring |
| Alarm Contacts | Send alarm signals when the circuit breaker trips due to faults |
| Shunt Release | Enable remote control of circuit breaker opening (per esempio., for fire protection linkage) |
| Undervoltage Release | Automatically trip when the power supply voltage drops below the set value |
| Electric Operating Mechanism | Realize electric closing/opening, suitable for remote control or frequent operation scenarios |
The NM1-400S/3000 400A is a reliable 3-pole molded case circuit breaker with a high breaking capacity of 50kA and thermal-magnetic release protection. It is suitable for various industrial and commercial power distribution systems. Its standard configuration (without accessories) meets basic protection needs, and it can achieve function expansion by selecting different accessories to satisfy more complex system protection and monitoring requirements.
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