Automatic power switch 4P 1250A HIC491G

Automatic load switching

The device enables safe, automatic switching between two power sources – the public grid and a generator – without the need to disconnect the load before switching. It operates in three stable positions: I (grid) – 0 (off) – II (generator), with a visible indication of the current position. Switching occurs under load, but with a brief interruption in power supply – it is not a UPS system.

Construction and installation

Built as a fixed device mounted on a mounting plate in a distribution board, it is not suitable for DIN‑rail or front‑panel mounting. It has cable terminals for connecting wires, and its interior contains two series disconnectors stacked one above the other, with a locking mechanism preventing simultaneous engagement of both sources. The built‑in motor drive enables remote control and automatic switching without additional equipment. Manual switching is also possible via an emergency lever, and a lockout latch provides service safety.

Functionality and safety

The device serves as a main disconnect, a safety disconnect, and a maintenance disconnect – providing full circuit isolation during service. It has one normally open (NO) auxiliary contact that can be used for position indication or to control external devices, e.g., a generator. The rated short‑circuit current is 100 kA when using gl‑gG fuses, and the short‑time withstand current is 64 kA for 1 second – ensuring resistance to high overloads. IP00 protection class indicates no protection against touch or foreign objects – requiring installation in a closed distribution board. The device operates at 380–415 V AC, with a working power up to 822 kW at 400 V for AC-1 and 562 kW for AC-23.