Liebert Series 600T - Manual (Page 23)

Theory of Operation 17
Operation After End-of-Discharge
The battery time screen displayed on the control panel enables you to estimate when battery shutdown will occur.
You will have enough time to energize an alternate AC power source or to initiate an orderly shutdown of the
critical load. If the battery plant discharges to the shutdown point during an outage, the UPS automatically dis-
connects the load, the AC input, and the battery. After AC input power is restored, the rectifier can be manually
restarted by the user.
Battery Disconnect
The external module battery disconnect (MBD) circuit breaker is used to isolate the UPS module from the bat-
tery during maintenance and to automatically disconnect the battery from the inverter at the end of battery dis-
charge. The MBD circuit breaker can be opened or tripped automatically, from the control panel, or manually. It
must be closed manually.
Battery Charge Current Limiting
The battery recharge current, after a battery discharge, is limited to between 1 and 25% (adjustable) of the full
load discharge current. An additional (optional) charge-limiting circuit can be activated by external dry contact
closure (field supplied) for use when operating on a back-up generator. These two levels of control regulate the
amount of current that flows from the power source to the battery while the battery is recharging.
The battery charge current limit is factory set at 10% for normal operation and at 1% for alternate power source
recharge operation.
Battery Equalize Charge Circuit
The battery equalize charge feature can be manually initiated or it can be programmed to operate automatically.
Either can be selected from the battery equalize screen displayed on the control panel.
The battery equalizing charge circuit increases the rectifier/charger output voltage to charge the battery any time
there is a power outage of 30 seconds or longer. The equalizing voltage is slightly higher than the float voltage.
This decreases the time required to recharge the battery.
NOTE
Do not use equalize charging with valve-regulated lead-acid batteries
Consult the battery manufacturer's manual for specific information about equalize
charging.