WSB1LE-80 2P Residual Current Breaker with Overcurrent Protection

Residual Current Circuit Breaker (RCCB, commonly known as leakage switch) is a leakage protection device operating based on Kirchhoff’s current law, which detects the vector sum of currents in the live and neutral lines in real time. When leakage occurs in the circuit and the current difference reaches the rated operating value, it can trip and cut off the power supply rapidly within milliseconds. It is mainly used to prevent personal electric shock accidents and electrical fires caused by leakage. Pure RCCB only has leakage protection, without overload or short-circuit protection functions.

Abbreviated as RCBO (Residual Current Breaker with Overcurrent), it is an integrated protection appliance that combines a residual current (leakage) protection unit and an overcurrent (overload + short-circuit) protection unit. A single device can realize the dual functions of RCD (leakage protection) + MCB (overload and short-circuit protection) at the same time, without separate installation and saving distribution space.

RCBO (Residual Current Breaker with Overcurrent) is the only integrated device with both types of protection. It integrates a zero-sequence current transformer (leakage detection) and thermal + electromagnetic trip mechanisms (overcurrent protection) inside, which can respond quickly to three types of faults: overload, short-circuit and leakage, and realize full-dimensional circuit protection with a single unit.

The three are trip curve types classified by the multiple of instantaneous trip current, corresponding to different load inrush characteristics:

• Type B: Instantaneous trip at 3~5 times rated current, with the highest sensitivity. Suitable for pure resistive loads and circuits sensitive to current inrush, such as precision instruments and resistance heating equipment.
• Type C: Instantaneous trip at 5~10 times rated current, general-purpose curve. Suitable for ordinary lighting, sockets and small inductive loads, and is the mainstream choice for civil and commercial scenarios.
• Type D: Instantaneous trip at 10~20 times rated current, with the strongest inrush resistance. Suitable for inductive loads with high starting current, such as motors, transformers and air compressors.

The core differences are instantaneous trip threshold and application scenarios:

Trip current multiple: Type B is 3\5 times rated current, Type C is 5\10 times rated current;

Sensitivity: Type B is more sensitive to inrush current and can trip instantaneously with slight overcurrent; Type C can tolerate certain starting inrush and is less prone to false tripping;

Application: Type B is suitable for pure resistive loads without starting inrush; Type C is suitable for ordinary civil and commercial mixed loads with starting current, with stronger universality.

There are two dimensions for the three most common classifications in the industry:

Classified by trip curve: Type B, Type C, Type D, corresponding to different instantaneous trip characteristics and load adaptability;

Classified by protection function: MCB (overload & short-circuit protection), RCD (leakage protection), RCBO (comprehensive leakage & overcurrent protection).

In daily distribution selection, the B/C/D trip curve classification is the most widely used.

The two have completely different protection principles and protection objects:

• Circuit breaker (MCB): Targets overcurrent faults, realizes overload protection through thermal trip and short-circuit protection through electromagnetic trip. Its core function is to protect circuits and equipment from being burned by excessive current.
• RCD: Targets leakage faults, triggers trip by detecting zero-sequence current difference. Its core function is to prevent personal electric shock and leakage fire.
  In engineering, they are usually used together to realize complete circuit protection.

Overcurrent is divided into two types: overload current and short-circuit current:

Overload current: The current slightly exceeds the rated value and lasts for a long time, caused by excessive total load and circuit overload. The hazard is continuous heating of conductors and accelerated insulation aging, which may cause fire in the long term.

Short-circuit current: Caused by direct short circuit between live and neutral/ground lines, the current instantly reaches dozens to hundreds of times the rated value. It is extremely destructive, will burn equipment instantly and ignite surrounding combustibles, and is one of the most serious electrical faults.

The standard installation process is as follows:

• Power-off operation: Completely disconnect the upstream power supply, and operate after verifying no electricity;
• Rail fixation: Snap the breaker onto the standard DIN 35mm rail and fasten it;
• Wiring: Upper terminals connect to incoming power, lower terminals connect to downstream load. Strictly correspond to the phase sequence of live line L and neutral line N according to terminal marks, and reverse connection is strictly prohibited;
• Function verification: After closing and powering on, press the test button to confirm normal tripping;

Note: Low-voltage electrical installation has electric shock risk, it is recommended to be operated by certified professional electricians.

The two have completely different protection principles and protection objects:

• Circuit breaker (MCB): Targets overcurrent faults, realizes overload protection through thermal trip and short-circuit protection through electromagnetic trip. Its core function is to protect circuits and equipment from being burned by excessive current.
• RCD: Targets leakage faults, triggers trip by detecting zero-sequence current difference. Its core function is to prevent personal electric shock and leakage fire.

In engineering, they are usually used together to realize complete circuit protection.