Nortel DMS-100 Series Maintenance Manual page 51

contains the OPM charge bus. The charge bus is a dc-to-dc converter with
output to a maximum of 5V higher than the load bus, rectifier voltage. For
example, if the load bus voltage is set to -52.0V dc, the maximum charge
bus voltage is -57.0V dc ± 2%. Refer to the figure "OPM with Strings 0
and 4 on the Charge Bus; all others on Load Bus".
The charge bus is a current taper charger where output current drops as the
voltage increases. For example, assume the load bus rectifiers are set to
52.0V dc. When a battery string moves from the load bus to the charge
bus, the charge bus voltage changes. The voltage adjusts to a higher
voltage than the load bus and supplies approximately 3A to the battery
string. As the voltage of the battery string increases, the charge bus output
current drops. When the battery string reaches the maximum charge bus
voltage of 57.0V, the output current of the charge bus is approximately 0A.
The NT8X02 contains a discharge resistor that is the discharge test bus. The
NT8X02 also contains the circuitry that moves the battery strings between the
following:
• load bus
• charge bus
• discharge test bus
• open circuit state
The OPM has the BCC 0 and BCC 1 cards. The BCC 0 card controls battery
strings 0, 1, 2 and 3. The BCC 1 card controls battery strings 4, 5, 6 and 7.
BCCDVR— The BCCDVR is the NT3X09AA in RMM slot 6. This card
relays battery control commands from system software to the NT8X02 BCC
card to move the battery strings. The BCCDVR moves the battery strings
between the open circuit state, load bus, charge bus and discharge bus. The
card appears as BCCDVR at the PES MAP display.
Test access card — The test access card is the NT3X09BA MTA card in RMM
slot 5. This card provides the LTU or MTU with access to the LCM line
circuits. This card also provides the LTU or MTU with access to each battery
string and the charge buses.
DMS-100 Family OPM Maintenance Manual ISN07 (TDM)/SN07 (DMS) and up
OPM maintenance summary 1-35