American Power Conversion MX28B4800 Controls and Indicators, Battery/Load Low Voltage Disconnect

Battery Temperature Compensation

The Battery Float Voltage is set to the value recommended by the battery manufacturer in order to maintain correct battery charge at 25ºC. As temperature rises, electrochemical activity in a battery increases. Similarly, as temperature falls, electrochemical activity in a battery decreases. As temperature rises charging voltage should be reduced to prevent overcharge and increased as temperature falls to prevent undercharge. The DC power system uses Battery Temperature compensation to change output voltage to compensate for temperature changes. This temperature compensation function is programmed into the PSCU using the compensation parameters settings. Default settings can be changed to values recommended by the particular battery manufacturer.

Battery/Load Low Voltage Disconnect

In order to prevent damage to the battery due to deep discharge, the DC power system has hardware and software support for a battery or load Low Voltage Disconnect (LVD). A battery LVD has the loads permanently attached to the rectifiers and the battery is disconnected from the system. A load LVD has the battery permanently attached to the rectifiers and the loads are disconnected from the system.

When the battery voltage reaches the threshold set by the LVD 1 Trip Voltage setting during discharge, the DC power system will activate the LVD contactor to disconnect the battery or load from the system. The LVD will remain open until AC power is restored to the system and the bus voltage reaches the level defined by the LVD 1 Reset Voltage variable.

NOTE: The LVD is normally energized and must be commanded to open. This assures that the LVD will remain closed even if the controller fails or is removed.

5.6. Controls and Indicators

CAUTION: The controller and the Web/SNMP card have lithium batteries. These batteries are not field serviceable.

•Danger of explosion if battery is replaced by an incorrect type.

•Dispose of used batteries according to the manufacturer’s instructions.

Front Panel User Interface

The MX28B control unit provides a user interface designed with a hierarchical menu that can be viewed on the 32-character (2 X 16) display by “navigating” with the “Õ” (left), “Ö” (right), “×” (up), and “Ø” (down) arrow keys located on the front panel. The selected item on the display is identified by the cursor cycling beneath its characters.

The “M” (modify) key and the arrow keys are used to set parameters and text to customize the system operation for a specific application. Items that can be modified have "m+" in the upper

MX28B1200/2400 MX28B1200/4800 –48 VDC User’s Manual Page 35