What does RCD, RCCB, MCB, RCBO mean? What’s the difference?

RCD, RCCB, MCB, RCBO

RCCB: Residual Current Circuit Breaker with Overcurrent Protection, residual current action circuit breaker. The residual current operated circuit breaker has no overcurrent protection function, that is, the leakage switch.

RCD: It is a leakage protection device, including a leakage switch and a leakage protection circuit breaker.

RCBO: It is a leakage protection circuit breaker.

MCB: Miniature circuit breaker MCB, used for overload and short circuit protection.

Difference

1. Different properties: Miniature circuit breakers are the most widely used terminal protection appliances in building electrical terminal power distribution devices. Leakage protection circuit breaker is a switching device to prevent fire and explosion accidents caused by human body electric shock or leakage in low-voltage lines. The leakage protection device is a grounding protection device used to prevent personal electric shock and accidents caused by leakage. Leakage protectors are used to protect people from electric shocks that may be fatal when a leakage fault occurs in the equipment.
2. The characteristics are different: the leakage switch has the function of detecting and judging the leakage current, but does not have the leakage protection device with the function of cutting off and connecting the main circuit. The leakage protection device can act quickly, cut off the accident power supply, avoid the expansion of the accident, and ensure the safety of people and equipment. The miniature circuit breaker is composed of operating mechanism, contacts, protection devices (various releases), arc extinguishing system and so on.
3. Different uses: miniature circuit breakers are used for single-phase and three-phase short-circuit protection below 125A. The leakage release disconnects the main contact of the main circuit to play a protective role. Leakage protection device In places where there is a high risk of electric shock, such as construction sites and metal structures, Class I portable equipment or mobile equipment should be equipped with a high-sensitivity leakage protection device. Under normal circumstances, the leakage switch is used to start the infrequent conversion of the line.

Precautions

1. The working neutral line N of the leakage protector protection circuit must pass through the zero-sequence current transformer. Otherwise, after it is turned on, there will be an unbalanced current that will cause the leakage protector to malfunction.
2. The zero-sequence current transformer is not allowed to connect to the zero-sequence protection line (PE). Because when the protection line (PE) passes through the zero-sequence current transformer, the leakage current passes through the PE protection line and then passes through the zero-sequence current transformer, resulting in current offset, and no leakage current value can be detected on the transformer. When a fault occurs, the leakage protector will not operate and will not be able to protect.
3. The working neutral line of the control circuit cannot be repeatedly grounded. On the one hand, when grounding is repeated, under normal working conditions, part of the working current returns to the neutral point of the power supply through repeated grounding, and an unbalanced current will appear in the current transformer. When the unbalanced current reaches a certain value, the leakage protector will malfunction.