American Power Conversion MX28B200 - Manual (Page 29)

MX28B200/400 –48 VDC User’s Manual (990-9133) Page 23
4 Operation
4.1. Technical Description
The MX28B-200/400 Power System is designed to supply safe –54 VDC primary power
through the use of up to eight rectifier modules. In conjunction with an external battery
string, it will supply backup power as well. The Power System Control Unit (PSCU) will
monitor all MX28B functions and provides battery management including controlled
battery recharge with temperature compensation and low voltage disconnect. Integrated
DC output distribution supports loads ranging from ¼ Amp all the way to 100 Amp is
available. Battery recharging, temperature compensation and low voltage disconnect are
included. The controller can monitor up to 4 discrete external events with dry contact
inputs.
4.2. Rectifier Management
AC Input Power
The basic component of the power system is the rectifier module, which rectifies utility
AC into nominal 48 Volts DC. Each rectifier module requires 208/220/240V AC
(MRF28H54BV), or 277V ac (MRF28H54BV50) single-phase, 50/60 Hz. A breaker
installed in a remote panel should individually protect each rectifier circuit.
DC Output Power
The DC outputs of all the rectifiers in the system are connected to a common bus that is
rated to carry the current of the entire system. The rectifier modules will equally share
the entire load, independent of the PSCU. The rectifiers will continue to provide DC
power if the PSCU is removed or fails.
Rectifier alarms reporting
The rectifier has numerous sensors inside the unit that monitor fan fail, high temperature,
high/low voltage, etc. These rectifier sensors trigger outputs that are monitored by the
PSCU. In addition rectifier current is measured inside each rectifier. The PSCU can
trigger output relays in the event of a rectifier alarm. Refer to Section 4.6 for PSCU
control functions.