Vertiv Liebert MBSM - Remote Commands; Excluding Bus a; Excluding Bus B; Excluding Bus a and B

Vertiv
™
|Liebert
®
MBSM
™
User Manual | 20
2.12 Remote Commands
There are two normally open inputs provided on XT1 for remote commands. These inputs are
biased at 230VAC. Relays used to close them must be rated accordingly.
2.12.1 Excluding Bus A
When the corresponding terminal voltage-free contact is closed, the Liebert MBSM is forced onto
Bus B and the UPS A system follows the reference signal generated by the Liebert MBSM.
2.12.2 Excluding Bus B
When the corresponding terminal voltage-free contact is closed, the Liebert MBSM is forced on
to Bus A and the UPS B system follows the reference signal generated by the Liebert MBSM.
2.12.3 Excluding Bus A and B
When both contacts are closed, the Liebert MBSM reference signal is generated by an internal
quartz oscillator. Both UPS systems will follow the reference signal generated by the Liebert
MBSM.
Table 3 Lamp indications
Lamp Title
Normal
Condition Non-Condition
Bus A Active Off
On indicates synchronization on Bus A and Bus B forced to A due to buses
OOS detected
Bus B Active Off
On indicates synchronization on Bus B and Bus A forced to B due to buses
OOS detected
L1 System OK On System OK —
L2 System
Fault
Off On when both buses not available or system fault
Forced Bus A Off
On indicates synchronization on Bus A and Bus B forced to A by external
command
Forced Bus B Off
On indicates synchronization on Bus B and Bus A forced to B by external
command