CHINT NXB-63 Miniature Circuit Breaker, 1-63 A

A 63 A DIN-rail breaker for final distribution boards

The NXB-63 is a miniature circuit breaker from the CHINT NXB series. It gives overload protection, short-circuit protection and positive isolation for AC 50/60 Hz circuits in lighting, socket and small-power sub-circuits. It is one of the most specified modular breakers in the CHINT range because one frame covers 1 A to 63 A, six pole configurations and three tripping curves.

Technical specifications

Choosing the curve, pole count and derating

Type B trips between 3 and 5 times In and suits long cable runs and resistive loads. Type C trips between 5 and 10 times In and is the normal choice for lighting and general power. Type D trips between 10 and 16 times In for loads with high inrush such as small transformers. The catalog states that the NXB-63 is not suited to direct starting of high-inductive or high-capacity loads such as fans, motors, electric heating equipment and capacitor cabinets, so a motor-rated device should be used for those.

When several breakers sit side by side, the catalog gives recommended current reduction of 0.90 to 0.95 In for up to three devices, 0.86 to 0.80 In for four to six, 0.78 to 0.76 In for seven to nine and 0.76 In above nine. The thermal element is referenced to 30 degC, and the rated current changes by roughly 0.03 to 0.05 In for every 10 degC above or below that. In a hot switchroom or an enclosure in direct sun, size the breaker from these tables, not from the nameplate alone.

Ordering code and what to confirm

The CHINT ordering example is written as frame, poles, curve plus current and breaking capacity, for example NXB-63 3P C63 6kA, which carries article code 814176, or NXB-63 1P C16 6kA with code 814014. The 3P+N and 1P+N versions are marked N on the right. Copper conductors are required: 1 mm2 up to 6 A, 1.5 mm2 for 10 A, 2.5 mm2 for 16 and 20 A, 4 mm2 for 25 A, 6 mm2 for 32 A, 10 mm2 for 40 and 50 A and 16 mm2 for 63 A.

Before ordering, confirm the number of poles and neutral position, the curve, the breaking capacity needed at the board (6 kA here; the NXB-63H version is rated higher), and the accessories to fit. The product is installed and maintained by qualified personnel only and does not protect people against electric shock, so earth-leakage protection is specified separately. For a comparable European device see the Siemens 5SY4504-7, or browse the circuit breakers category.

Documents and quotation

The CHINT NXB series catalog and the NXB-63 and NXB-63H user instruction are attached. The specification table above comes from those documents. Send the full description, for example frame, poles, curve, current and quantity, through the quotation form and Seven Star LLC will confirm availability for your project.