ABB REF542PLUS 2RCA029395 A0031 Dual-Breaker Protection Relay

REF 542plus is a Switchgear Multifunction Protection and Switchgear Control Unit and it is the further development of the former REF 542 multifunctional unit. Like its predecessor, it features the following functions:
* Protection
* Measurement
* Control
* Monitoring and self diagnosis
* Communication
All above-mentioned and also power quality functions are integrated into a programmable environment. The exceptional flexibility and scalability of this new generation device lead to a smart solution where the traditional approach would be ineffective and expensive.
The following figures Fig. 3.-1 and Fig. 3.-2 show examples of the REF 542plus installation in several switchgears.

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.