Residual current circuit breaker Acti9 iID-40-4-300-B-SI 40A 4-pole 300mA type B-SI A9Z64440

Circuit protection with inverters and motors

In modern installations, where inverters, heat pumps, or emergency power systems are increasingly used, traditional residual current devices may fail. These devices generate direct current (DC) components that "trick" classic detection mechanisms. The Acti9 iID switch of type B-SI was designed specifically to react effectively to such conditions. Its type B sensitivity allows for the detection of sinusoidal, pulsating, and direct residual currents, which is crucial for safety in circuits with power electronics. Thanks to SI (Super Immunity) technology, the device features increased immunity to electromagnetic interference, minimizing the risk of nuisance tripping in challenging industrial or commercial environments.

Precision of operation and mounting safety

The rated current of 40 A and sensitivity of 300 mA define the application range of this model – it is ideal as group protection for larger installations or as the main fire protection in distribution boards. Unlike selective (S) types, this model operates instantaneously, ensuring a rapid response in the event of a dangerous current leakage. The 4-pole construction allows for the complete disconnection of all active conductors in three-phase networks with a neutral.

Mounting and handling have been designed with the installer's convenience in mind:

• A width of 4 modules (72 mm) optimally utilizes space in the DIN rail cabinet.
• The ability to connect wires with cross-sections from 1 to 35 mm² (rigid) and 1 to 25 mm² (flexible) eliminates the need for additional ferrules in many cases.
• The double terminal system allows for flexible connection from both the front and the rear, facilitating cable routing in dense distribution boards.
• The DIN rail mounting mechanism allows for quick removal of the device even with busbars installed.

Visual status control and durability

End-user safety is supported by intuitive visual indicators. The VisiTrip mechanism informs via a red color about a trip caused by a short circuit or current leakage, distinguishing it from a simple manual switch-off or loss of voltage. Meanwhile, the VisiSafe function (green indicator) confirms the physical disconnection of the contacts, providing certainty that there is no voltage on the output side before commencing service work.

The device complies with rigorous safety standards (including IEC/EN 61008-2-1, IEC/EN 62423) and is adapted for operation in temperatures from -25 °C to 60 °C. High resistance to current surges (3 kA) and withstandable impulse voltage (6 kV) guarantee reliability even during sudden voltage spikes in the network. Key technical features of the device include the B-SI sensitivity type, which detects direct currents and interference from inverters, a rated current of 40 A providing appropriate continuous load capacity for the circuit, and a residual sensitivity level of 300 mA, used mainly for fire and group protection. The device operates in three-phase networks with an operating voltage of 400 V AC, occupies a standard mounting width equal to 4 DIN modules, and has an IP rating of IP20, which means protection against finger contact when used with an appropriate distribution enclosure.

Thanks to this solution, the installer receives a device ready to work in demanding conditions, and the end user – the certainty that their installation is protected even in the presence of advanced control electronics.