Power switch controller HZI855

Power Switch Controller HZI855 – communication and control in emergency power systems

The HZI855 controller is an accessory for automatic power transfer systems (ATSE) that combines measurement, control, and communication functions in a single device. It acts as an interface between power sources – e.g., the public grid and a generator – and circuit breakers or contactors, enabling full automation of the transfer process without manual intervention.

The device supports two voltage sources (L1–L2 or L1–L2–L3–N) in the range of 88–575 VAC, and its built‑in DPS module automatically switches the controller’s supply to the secondary source in case of a main‑source failure. It does not require external power – it operates from the voltage detected directly on the controlled circuits. Optionally, an auxiliary 24 VDC supply (up to 6 W) can be connected, ensuring operation even with a total loss of voltage in the main circuits.

It has six programmable inputs and six latch‑type (bistable) relay outputs, which can drive, for example, disconnect coil relays, drive motors, or alarm signaling. The default configuration is adapted to typical applications: HIB4xxM, MCCB or ACB – but all functions can be changed via the LCD menu. Outputs 5 and 6 have a safety function: upon loss of controller power they automatically activate to force generator start‑up – critical in high‑reliability systems.

Communication is carried out over an RS485 bus using the Modbus protocol, allowing integration with BMS, SCADA, or monitoring panels. The terminals are screw‑type – for control and signal circuits the permissible conductor cross‑section is 1.5–2.5 mm² (rigid or flexible), with a tightening torque of 0.5–0.6 Nm. The RS485 bus requires LiYCY twisted pair with a cross‑section of 0.14–1.5 mm² and a tightening torque of 0.22–0.25 Nm.

The controller is designed for mounting on the door of a distribution board and has an IP65 protection rating – meaning resistance to dust and water jets. It operates over a wide temperature range: from –30 °C to +70 °C – both during operation and storage. Power consumption is only 10 W.

In the event of a fault (e.g., missing neutral conductor) the controller reacts automatically: it blocks transfer to the secondary source and triggers an alarm (input IN5). Emergency stop (IN6) causes a complete system lockout – the load remains disconnected until the operator manually acknowledges the error.

For installation, the kit includes: 4 mounting screws for the door and 4 mounting brackets. Achieving full IP65 protection requires the additional accessory HZI501 (seal). The controller is not a replaceable part – it is a system component that must be configured for the specific application.

All technical data comply with IEC 60947-6-1 and IEC 61010-2-201 standards.