Control unit for a multipole electrical circuit breaker, said unit comprising: - a central body including: • an interconnect device comprising: o input contact pads capable of being electrically connected to power input terminals of a multipole electrical circuit breaker in order to receive primary electrical voltages from the circuit breaker, o an electrical power circuit including a voltage divider bridge, configured to convert the primary electrical voltages into secondary electrical voltages; • a control device provided with a measuring circuit capable of measuring the secondary electrical voltages provided by the electrical power circuit, the control device being programmed to determine an operating state of the circuit breaker as a function of the secondary electrical voltages measured by the measuring circuit; - a removable power supply module received in a housing of the central body, the module: • being electrically connected to the interconnect device in order to collect the primary electrical voltages, and • comprising a power converter configured to transform the collected primary electrical voltages into a supplementary secondary electrical voltage (V2') and to supply power to a shared power supply bus of the control device using the supplementary secondary electrical voltage (V2'), the control unit being designed so that the power supply module can be removed without affecting the operation of the control device. - a central body including: • an interconnect device comprising: o input contact pads capable of being electrically connected to power input terminals of a multipole electrical circuit breaker in order to receive primary electrical voltages from the circuit breaker, o an electrical power circuit including a voltage divider bridge, configured to convert the primary electrical voltages into secondary electrical voltages; • a control device provided with a measuring circuit capable of measuring the secondary electrical voltages provided by the electrical power circuit, the control device being programmed to determine an operating state of the circuit breaker as a function of the secondary electrical voltages measured by the measuring circuit; • an interconnect device comprising: o input contact pads capable of being electrically connected to power input terminals of a multipole electrical circuit breaker in order to receive primary electrical voltages from the circuit breaker, o an electrical power circuit including a voltage divider bridge, configured to convert the primary electrical voltages into secondary electrical voltages; o input contact pads capable of being electrically connected to power input terminals of a multipole electrical circuit breaker in order to receive primary electrical voltages from the circuit breaker, o an electrical power circuit including a voltage divider bridge, configured to convert the primary electrical voltages into secondary electrical voltages; • a control device provided with a measuring circuit capable of measuring the secondary electrical voltages provided by the electrical power circuit, the control device being programmed to determine an operating state of the circuit breaker as a function of the secondary electrical voltages measured by the measuring circuit; - a removable power supply module received in a housing of the central body, the module: • being electrically connected to the interconnect device in order to collect the primary electrical voltages, and • comprising a power converter configured to transform the collected primary electrical voltages into a supplementary secondary electrical voltage (V2') and to supply power to a shared power supply bus of the control device using the supplementary secondary electrical voltage (V2'), the control unit being designed so that the power supply module can be removed without affecting the operation of the control device. • being electrically connected to the interconnect device in order to collect the primary electrical voltages, and • comprising a power converter configured to transform the collected primary electrical voltages into a supplementary secondary electrical voltage (V2') and to supply power to a shared power supply bus of the control device using the supplementary secondary electrical voltage (V2'),