Product Specifications
Technical Parameters
| Parameter | Value |
|---|---|
| Product Series | NB7 |
| Product Type | Miniature circuit breaker |
| Rated Operational Voltage Ue | AC 230V/400V for 1P; AC 400V for 2P, 3P and 4P |
| Rated Current In | 1A, 2A, 3A, 4A, 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A, 63A |
| Rated Insulation Voltage Ui | 500V |
| Rated Impulse Withstand Voltage Uimp | 4kV |
| Rated Frequency | 50Hz |
| Number of Poles | 1P, 2P, 3P, 4P |
| Instantaneous Tripping Characteristics | B, C, D |
| Mechanical Endurance | 10,000 operating cycles |
| Electrical Endurance | 4,000 operating cycles |
| Pollution Degree | 2 |
| Degree of Protection | IP20 |
| Installation Category | II, III |
| Connection Method | Screw-clamp connection |
| Tightening Torque | 2.0N·m |
| Applicable Standards | GB/T 10963.1, IEC 60898-1 |
| Certification | CCC |
Rated Short-Circuit Breaking Capacity
| Rated Current In | Tripping Characteristic | Poles | Rated Voltage Ue | Rated Short-Circuit Breaking Capacity Icn |
|---|---|---|---|---|
| 1A–40A | B, C | 1P | 230V/400V | 6,000A |
| 1A–40A | B, C | 2P, 3P, 4P | 400V | 6,000A |
| 50A, 63A | B, C | 1P | 230V/400V | 4,500A |
| 50A, 63A | B, C | 2P, 3P, 4P | 400V | 4,500A |
| 1A–63A | D | 1P | 230V/400V | 4,500A |
| 1A–63A | D | 2P, 3P, 4P | 400V | 4,500A |
Overcurrent Protection Characteristics
| Test Item | Tripping Characteristic | Test Current | Initial Condition | Specified Time or Operating Condition | Expected Result |
|---|---|---|---|---|---|
| Conventional non-tripping test | B, C, D | 1.13In | Cold state | t ≥ 1h | No tripping |
| Conventional tripping test | B, C, D | 1.45In | Immediately after the previous test | t < 1h | Tripping |
| Overload tripping test | B, C, D | 2.55In | Cold state | 1s < t < 60s for In ≤ 32A; 1s < t < 120s for In > 32A | Tripping |
| Instantaneous tripping lower limit | B | 3In | Cold state | t ≤ 0.1s | No tripping |
| Instantaneous tripping lower limit | C | 5In | Cold state | t ≤ 0.1s | No tripping |
| Instantaneous tripping lower limit | D | 10In | Cold state | t ≤ 0.1s | No tripping |
| Instantaneous tripping upper limit | B | 5In | Cold state | t < 0.1s | Tripping |
| Instantaneous tripping upper limit | C | 10In | Cold state | t < 0.1s | Tripping |
| Instantaneous tripping upper limit | D | 16In | Cold state | t < 0.1s | Tripping |
Recommended Conductor Cross-Section
| Rated Current In | Recommended Copper Conductor Cross-Section |
|---|---|
| 1A–6A | 1mm² |
| 10A | 1.5mm² |
| 16A, 20A | 2.5mm² |
| 25A | 4mm² |
| 32A | 6mm² |
| 40A, 50A | 10mm² |
| 63A | 16mm² |
The recommended conductor cross-sections and product selection data are for reference only. Final selection should be based on the installation method, ambient temperature, load characteristics and applicable electrical regulations.
Product Overview
The NB7 series miniature circuit breaker is designed for use in AC 50Hz low-voltage distribution systems with a rated operational voltage of AC 230V or AC 400V and a rated current range from 1A to 63A. It protects circuits and electrical equipment against overload and short-circuit faults by automatically interrupting the current when abnormal operating conditions occur. Under normal conditions, the NB7 can also be used for infrequent switching of electrical circuits. During circuit or equipment maintenance, it may serve as an isolating device for disconnecting the power supply. The product is available in 1P, 2P, 3P and 4P configurations and provides B, C and D instantaneous tripping characteristics. The appropriate version can be selected according to the circuit type, load characteristics and starting current. The rated insulation voltage is 500V, and the rated impulse withstand voltage is 4kV. The circuit breaker has pollution degree 2, an IP20 protection rating and installation categories II and III. Mechanical endurance is 10,000 operating cycles, while electrical endurance is 4,000 operating cycles. The rated short-circuit breaking capacity varies according to the rated current and tripping characteristic. B- and C-curve products rated from 1A to 40A have a rated short-circuit breaking capacity of 6,000A. B- and C-curve products rated at 50A and 63A, as well as D-curve products rated from 1A to 63A, have a rated short-circuit breaking capacity of 4,500A. The NB7 series complies with GB/T 10963.1 and IEC 60898-1 and is CCC certified. It is suitable for industrial facilities, commercial buildings, high-rise buildings and residential distribution systems.
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