ABB Relion 650 Series Technical Manual page 673

1MRK 511 424-UEN B
Bay control REC650 2.2 IEC
Technical manual
IEC1MRK002801-AA11-UTAN-RAM V2 EN-US
Figure 298: Binary in/out module (IOM), input contacts named XA corresponds
to rear position X31, X41, and so on, and output contacts named
XB to rear position X32, X42, and so on
The binary input/output module version with MOV protected contacts can for
example be used in applications where breaking high inductive load would cause
excessive wear of the contacts.
The test voltage across open contact is lower for this version of the
binary input/output module.
Section 16
IED hardware
SEMOD175370-4 v1
667