RCCB and ELCB RCBO are leakage circuit breakers. Are they essentially different?
1、 Different properties: ELCB is a leakage circuit breaker; Both RCCB and RCBO are residual current operated circuit breakers, but RCBO is equipped with overcurrent protection.
2、 The working principle is different: ELCB is that a human body touches the line end of the power supply, that is, the live line, or the internal leakage of electrical equipment. The current does not flow through the zero line, resulting in unequal current. After detecting this current difference, the leakage protector trips immediately to protect the safety of human and electrical equipment; RCCB and RCBO are mainly used to detect the residual current. When the residual current value exceeds the reference value, the contact of the main circuit will be disconnected.
3、 The applicable environment is different: ELCB is suitable for low-voltage power grid with ungrounded transformer neutral point and low-voltage distribution system with grounded transformer neutral point; RCCB and RCBO are applicable to lines with AC 50Hz or 60Hz, rated voltage of single pole, two wires, two poles, 230V, three-level / three-level, four wires, four-level 400V and rated current of 60A. RCBO is mainly applicable to the application of overcurrent protection (overload and short circuit) and ground fault current protection functions at the same time.

RCCB, ELCB, RCBO and RCD are abbreviations in English.
RCCB: residual current circuit breaker
ELCB: earth leakage circuit breaker
RCD: residual current device
RCBO: residual current circuit breaker with overcurrent protection
According to ABB’s sample, the difference between RCCB and RCBO is that the former does not have overcurrent protection and the latter does. RCD should include both RCCB and RCBO. ELCB is used for earth leakage current protection, which is different from residual current.