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MX28B-400 +24V Product Manual
990-9218 11
4.2 Power Output Capacity
The power supplies a maximum of 400 amps or 300 amps with N+1 redundancy. The housing
for this configuration provides space for one rectifier shelf that can hold up to four rectifiers, a
control unit, and one tier of up to 24 distribution circuit breakers.
4.3 Rectifiers
The rectifiers are APC DC Network Solutions Inc. Model MRF28H27BV with specifications as
follows:
•= Input Voltage: 176-264V ac (230V ac nominal) @ 45-66 Hz
•= Input Current per Rectifier: 13.9 Amps @ 230V ac
•= Apparent Power Factor: 99% Typical, 98% Minimum
•= Output Voltage: 27.2 V dc
•= Over-voltage Protection: Set at 31.5 V dc
•= Output Current per Rectifier: 100A Maximum, Continuous
•= Power Output per Rectifier: 2800W Continuous, Vin > 198V ac
•= Efficiency: 89% Typical
•= Cooling: Fan cooled, front to rear airflow
•= Ambient Temperature: -25°C to 65°C Operational
4.4 Control Unit
The microprocessor-based power system control unit is 1U high (1.75”) and provides control
and monitoring functions. Features implemented are:
•= 32-character alphanumeric display
•= LED alarm and status indicators
•= Standard voltage and battery charging control
•= Battery temperature compensation (optional)
•= Monitoring of up to two shelves of four rectifiers each
•= Individual alarm monitoring of 24 breakers
•= Eight alarm / annunciation relays (Major, Minor, and six user defined) with form C contact
outputs
•= Four external alarm inputs (either N.O. or N.C. contacts)
•= Control of either a battery or a load LVD
4.5 AC Input Power
Each rectifier requires 208/220/240V ac, single-phase, 50/60 Hz, supplied through an external
20-amp two-pole breaker. A rear located enclosure, with two holes for customer-supplied one-
inch conduit entry, provides a terminal strip(s) for ac input power connection and a separate
“Earth Ground” bar for connection of the safety ground wire(s).