Factory Hot Sale Series AC Miniature Circuit Breaker Wsb7-63 MCB 4p

An MCB is a manually operated, resettable electromechanical device that protects low-voltage circuits against overload and short-circuit currents. Inside the WSB7-63, a bimetallic strip provides inverse-time (thermal) tripping for sustained overcurrent, while a magnetic solenoid trips instantly on a high short-circuit current, both releasing a common spring-loaded mechanism to open the contacts.

A 4-pole breaker switches and protects all four conductors of a three-phase four-wire system (L1, L2, L3 and N). On a WSB7-63 4P, phase and neutral terminals are connected to the corresponding input busbar, and the four poles open simultaneously so the load is fully isolated for maintenance. It is typically used as the main incoming breaker for three-phase distribution boards.

The WSB7-63 frame size covers rated currents (In) up to 63 A, typically offered in standard stepping values such as 6 A, 10 A, 16 A, 20 A, 25 A, 32 A, 40 A, 50 A and 63 A. Selecting the correct rating means choosing the lowest value that carries the normal full-load current of the circuit without nuisance tripping.

The WSB7-63 is commonly supplied in B, C and D curves. Curve B trips magnetically at 3–5 In for mostly resistive lighting and socket circuits; curve C trips at 5–10 In for general commercial and inductive loads such as small motors; curve D trips at 10–20 In for high inrush loads such as transformers and welding equipment. Choose the curve to match the starting characteristic of the protected load.

Breaking (or interrupting) capacity is the maximum prospective short-circuit current the breaker can safely clear without failing. A higher breaking rating means the device can interrupt larger fault currents on the supply side, reducing risk of case rupture, welding or arc flash. The WSB7-63 is designed with a reliable high breaking capacity suitable for common low-voltage distribution applications.

Yes. The WSB7-63 is a standard DIN-rail MCB that clips onto a 35 mm EN 60715 rail inside a distribution board, allowing fast installation and replacement. Its compact, modular width lets contractors pack multiple feeders into one enclosure while maintaining clear wiring access at the top and bottom terminals.

The WSB7-63 series is designed and type-tested to IEC 60898-1, the international standard for AC miniature circuit breakers for household and similar installations, and carries CE marking for the European market. This ensures consistent thermal and magnetic tripping characteristics, impulse withstand and endurance across production batches.

Because it switches all three phases plus neutral, the 4P version is typically used as the main isolator or incomer breaker for three-phase distribution boards, three-phase machinery, three-phase UPS and inverter systems, and commercial/industrial lighting and power panels. It is not normally used for single branch circuits, where 1P or 2P breakers are more economical.

Nuisance tripping usually comes from selecting too small a rating, an incorrect tripping curve (e.g., a B curve on a motor circuit), high inrush currents, or loose terminals causing heat. Check the actual load current, verify the curve matches the load type, and ensure torque-tightened connections; if the breaker still trips repeatedly on start-up, consider a higher C or D curve rather than oversizing the breaker.

MCBs are largely maintenance-free, but they should be inspected periodically for overheated terminals, loose wiring and mechanical operation. Operate the ON/OFF handle a few times annually to keep the mechanism free, re-torque conductors to the specified value, and never replace an MCB with one of a higher rating or wrong curve without recalculating circuit protection.