Power circuit breaker h3+ P630 LSI 4x400A 50kA HMW401JR

Protection of High-Current Main Circuits

In industrial installations and main distribution boards where operating currents reach 400 A, it is crucial to use a device that not only disconnects the circuit but also responds precisely to faults. The compact power circuit breaker from the h3+ series, with a rated continuous current of 400 A and four poles, is designed for operation at voltages from 220 to 690 V. Its primary function is to protect the installation against the effects of overloads and short circuits, ensuring safety for both cables and connected loads. The device features a high switching capacity – at 400 V, it can safely interrupt short-circuit currents up to 50 kA, making it suitable even for locations with high short-circuit power density in the network.

Flexible Protection Thanks to LSI Electronics

The heart of this circuit breaker is an LSI (Long-time, Short-time, Instantaneous) electronic protection module, allowing individual adjustment of the tripping characteristic to match the specifics of the protected circuit. Unlike simple thermal protections, here the installer has full control over the parameters. The overload protection (Ir) allows setting the tripping current in the range from 160 A to the full 400 A, enabling precise adaptation of the circuit breaker to the actual line load and avoiding false trips during short-term current surges. The time-delayed short-circuit protection (Isd) offers an adjustable range from approximately 218 A up to 4000 A; thanks to the adjustable time delay, it prevents immediate disconnection during short circuits that are not harmful to the main installation, thereby increasing selectivity with upstream protections in the distribution board hierarchy. Instantaneous protection (Ii) is also available as an additional safeguard against very high short-circuit currents.

Such a configuration is particularly useful in motor or transformer power supply systems, where it is necessary to distinguish between starting current and actual short circuits. Additionally, the built-in status indicator (LED) informs about device readiness (green), internal errors (flashing orange), or temperature exceedance (red), facilitating diagnostics without the need to disassemble the device.

Installation and Practical Functionality

The device is intended for fixed installation in distribution cabinets and is not suitable for DIN TH rail mounting – it requires dedicated screw mounting. Main cable connections are located at the front of the enclosure, facilitating wiring and access during maintenance. Connections are made via screw terminals, with a recommended tightening torque of 18 Nm for each contact. The IP40 degree of protection guards against the ingress of solid objects larger than 1 mm and water droplets falling at an angle up to 15 degrees, which is standard for devices installed inside enclosed distribution boards.

For monitoring and remote control purposes, an optional motorized actuator can be added, enabling remote switching of the circuit despite the lack of a factory-installed actuator. Standard equipment includes an off indicator and a potential-free alarm contact warning of an impending fault (exceeding 90% of the set current Ir). The lever mechanism allows visual identification of three states: ON (lever up), OFF (lever down), and tripped due to short circuit/overload (middle position). It is also possible to lock the lever with a standard padlock in the "ON" or "OFF" position, preventing accidental or unauthorized switching.

The device operates in a wide ambient temperature range from -25°C to +70°C and complies with IEC 60947-2 standards for low-voltage equipment. Thanks to the ability to test the mechanism using a test button and access to the interior of the module via a service flap, maintaining system functionality is simple and safe for technical personnel.