Manual Part 5

BFU-22
1 Product Overview
The BFU-22 supplies b attery backup system voltage to the RBS and
disconnects the battery when it has reached its lower discharge limit. The
contactor can disconnect and reconnect the battery with a control signal from
the Supervision Module (SM).
1.1 Main Functions
The BFU-22 has the following functions:
• Supplies priority power to transmission equipmen t. Power to transmis sion
equipment can be distributed ev en if a batte ry is not present. The rela y can
select the pow er source with a control signal from the SM
• Communicates on the Environmental and Power Control (EPC) bus (opto
cable) with the Distribution Switch Unit (DXU). If the EPC bus is no t present,
the BFU o perates at its default values. T he battery voltage, current and
temperature are monitored and alarms are sent on the EPC bus
• Disconnects the battery, if the current is too l ow or the temperatu re is too
high. Whe n the temperature returns to normal, the b attery i s reconnected.
• Sends a ‘‘Battery temperature sensor fault’’ message to the DXU w hen the
battery temperature is faulty
• Disconnects battery backup manually o r by control signals on the EPC bus
The SM provides self-detection of inte rnal faults and stores them in non-volatile
memory.
2 Dimensions
The phy sical characteristics of the B FU-22 are shown in the table below.
Table 1 BFU-22 Size a nd Weight
Height Width Depth Weight
267 mm 82 mm 226 mm 5 kg
3 Function Description
The block diagram of the BFU-22 is shown in the figure below.
3 (6)
EN/LZT 720 0276 Uen R2A