dual 48v and 24v dc power system

Product Information

Guardian Dual is a family of dual 48V and 24V DC power systems providing outputs of -48VDC and +24VDC in either 5RU/6RU rack-mount or free-standing cabinet configurations.

All versions can accommodate up to five or ten Guardian family high efficiency hot-swap rectifiers and dc-dc converters. The cabinet versions offer 1.4m, 1.8m or 2m floor standing cabinets or an 18RU high wall-mounted cabinet which also accommodate up to 3 battery strings.

A load current of 300A at -48V is available with battery charge current software controlled subject to an overall 360A while the secondary load is up to 250A at +24V. The rectifiers and dc-dc converters are internally fan cooled with speed control which is a function of load and temperature, keeping acoustic noise to a minimum.

The DC output circuits can provide up to 26 loads which utilize circuit breakers rated from 2A to 63A plus up to six 100A or 125A breakers that provide battery protection. An optional extension PDU module provides a further 24 load circuits. A programmable 400A low voltage battery disconnect (LVBD) is standard while one or two partial load disconnects (PLD), rated at 125A, 200A or 400A and also programmable, can provide non-critical load shedding when operating on batteries.



Output Voltage Maximum Current Maximum Power Format
Cabinet OR
23″ Rack-Mount
19″ Rack-Mount
Features and Options
  • Combined -48V and +24V system
  • Up to 19.2kW at -48V and 6kW at +24V
  • Configurable dual voltage distributions
  • Intelligent Battery Management
  • Energy management functions improve site level efficiency
Voltage 1 or 2 × 230VAC phase TN (Δ), 1 or 2 × 400VAC phase IT (Y)
Frequency 47-63Hz
Input Current<18A per rectifier
Power Factor >0.99 (typical)
Surge Protection Optional
Nominal Voltage -48VDC | +24VDC
Maximum Power

Cabinet/23" Rack, -48V/+24V: 19.2kW/6kW
19" Rack, -48V/+24V: 11.6kW/4.5kW

Maximum Current
(load + recharge)

Cabinet/23" Rack, -48V/+24V: 360A/250A
19" Rack, -48V/+24V: 300A/187.5A

Rectifier Types FMP25.48 | FMPe30.48
DC/DC Converter FMD15.24
Load Breakers

Cabinet/23" Rack, 26 × 2 – 63A maximum
19" Rack, 21 × 2 – 63A maximum

Battery Breakers 1-6 off (max 125A), 1-3 off (max 250A)
Battery Capacity Up to 720Ah using 4 × 180Ah strings (Cabinet only)
Controller ACX Advanced
Alarm Relays 4 Standard, up to 10 optional
Local Interface 4 × 20 LCD, 4 key menu, USB/RS232
Remote Interface Ethernet/Modem using PowCom™ software package
Visual Indication Green LED – System ON
Yellow LED – Message(s)
Red LED – Alarm(s)
External I/O 2 × Digital inputs + 2 x Digital outputs (Open collector)
Symmetry Inputs Up to 12
Programmable LVBD Cabinet/23" Rack, 1 × 400A or 500A
19" Rack, 1 x 400A
Programmable PLD Cabinet/23" Rack, 2 × 125A, 200A or 400A
19" Rack, 2 × 125A or 200A
Battery Battery Cable, M8 lugs
AC Input 16mm² (4AWG)
Load Breakers Negative termination directly from breakers. Common positive from AKG terminals
Alarms 1.5mm² (14AWG)
Operating Temp. Range -40°C to +75°C, derating over +55°C
Storage Temp. Range -40°C to +85°C
Dimensions, inches (mm) Cabinet: 23.1(600)W x 23.1(600)D x 55.1(1400)/70.9(1800)/78.7(2000)H
23" 5RU Rack: 23” mounting × 15.7(398)D × 8.75(222)H
23" 6RU Rack: 23” mounting × 15.7(398)D × 10.5(266)H
19" 5RU Rack: 19” mounting × 15.7(398)D × 8.75(222)H
19" 6RU Rack: 19” mounting × 15.7(398)D × 10.5(266)H
EMCETSI EN 300 386 V.1.3.2; EN61000-6-2 (Immunity); EN61000-6-3 (Emission)
Safety IEC 60950, UL/CSA 60950
Battery Disconnection Provides voltage controlled disconnection of batteries.
Boost Charging Manual time controlled or automatic boost charging with adjustable time and voltage levels.
Battery Tests Automatic or manual testing of batteries up to six times per year with a 10 test memory. Variables include test duration and end voltage.
Battery discontinuance test to ensure battery connection.
Enhanced Battery Monitoring Monthly logging of essential battery parameters including temperature, temperature hours, current, charging voltage and symmetry voltage, Data logged for 5 years.
Site Logs System tools developed to assist site management. Daily peak load and statistic logs available.
Symmetry Measurement Optional tool that measures batteries for early detection of thermal runaway.
Temperature Compensation Charging

Allows continuous adjustment of output voltage according to battery temperature.
Features include adjustable compensation factor and separate thresholds for high temperature alarms.

Load Shedding (PLD) Optional feature that allows voltage or time controlled disconnection of non-essential load.