ABB REF 542plus Technical Reference Manual page 12

REF 542plus REF 542plus
12
Multifunction Protection and Switchbay Control
Unit
Technical Reference Manual
Fig. 3.-2 REF 542plus installed in an air-insulated switchgear (AIS)
REF 542plus is composed of two parts: a base unit and a separate human machine
interface (HMI). The base unit contains the power supply, the processor board, the
analog input board and binary input and output (I/O) modules, as well as optional
modules for supplementary functions. The base unit and a HMI are connected with a
serial cable.
The HMI is a stand-alone unit with its own power supply. It can be installed on the
low voltage (LV) compartment door or in a dedicated compartment close to the
central unit. The HMI can be used to set the protection parameters to locally operate
the switching devices in the switchgear and to visualize events and measurements. A
shielded, isolated twisted pair according to the RS-485 standard interface connects
the HMI to the base unit. Fig. 3.-4 shows an installation of the central unit and the
HMI Control Unit in the LV compartment of a switchboard for the switchgear.
1MRS755859
A070118