Circuit breaker (4A; 4B) comprising an electronic trigger unit (14A; 14B) and a device (16A; 16B) for calibration of the electronic trigger unit (14A; 14B), the trigger unit (14A; 14B) comprising a device (22A; 22B) for triggering opening of contacts of the circuit breaker, control means (35A; 35B) of the trigger device (22A; 22B), and control means (36A; 36B) of the calibration device, the calibration device (16A; 16B) comprising at least one read device (32A, 34A; 32B, 34B) adapted to read the content of at least one first memory device (28A, 30A; 28B, 30B), each first memory device (28A, 30A; 28B, 30B) being adapted to memorise a predetermined identifier, each predetermined identifier being a parameter associated with the circuit breaker (4A; 4B), each first memory device (28A, 30A; 28B, 30B) being included either in the calibration device (16A; 16B) or in the circuit breaker , the control means (36A; 36B) of the calibration device being adapted to generate and transmit, to each calibration device, a command to read each predetermined identifier, the trigger unit (14A; 14B) being adapted to command opening of the contacts of the circuit breaker as a function of each predetermined identifier, characterised in that each read device (32A, 34A; 32B, 34B) comprises a shift register adapted to read, in response to the transmission of the read command, each predetermined identifier and to send to the trigger unit (14A; 14B) each read predetermined identifier, each read device (32A, 34A; 32B, 34B) comprising one or more inputs each able to receive at least one of the predetermined identifiers, each predetermined identifier comprising at least one data bit and at least one verification bit, each identifier being a parameter relating to a calibration value for triggering opening of the contacts of the circuit breaker (4A; 4B), the control means (36A; 36B) being adapted to verify, as a function of the verification bit or bits, the validity of the data bit or bits read and sent by each read device. the calibration device (16A; 16B) comprising at least one read device (32A, 34A; 32B, 34B) adapted to read the content of at least one first memory device (28A, 30A; 28B, 30B), each first memory device (28A, 30A; 28B, 30B) being adapted to memorise a predetermined identifier, each predetermined identifier being a parameter associated with the circuit breaker (4A; 4B), each first memory device (28A, 30A; 28B, 30B) being included either in the calibration device (16A; 16B) or in the circuit breaker , the control means (36A; 36B) of the calibration device being adapted to generate and transmit, to each calibration device, a command to read each predetermined identifier, the trigger unit (14A; 14B) being adapted to command opening of the contacts of the circuit breaker as a function of each predetermined identifier, characterised in that each read device (32A, 34A; 32B, 34B) comprises a shift register adapted to read, in response to the transmission of the read command, each predetermined identifier and to send to the trigger unit (14A; 14B) each read predetermined identifier, each read device (32A, 34A; 32B, 34B) comprising one or more inputs each able to receive at least one of the predetermined identifiers, each predetermined identifier comprising at least one data bit and at least one verification bit, each identifier being a parameter relating to a calibration value for triggering opening of the contacts of the circuit breaker (4A; 4B), the control means (36A; 36B) being adapted to verify, as a function of the verification bit or bits, the validity of the data bit or bits read and sent by each read device. <EOS>