Standard 19” Half Rack Lightweight Plug in Module
Switch Mode Conversion at >60KHz
N+1 Redundancy
High Efficiency
‘Hot’ Replacement of Modules
High Power 1200W to 7200W DC/DC Converter System
Telecom Systems are normally designed to work from exchange Battery. Several modern equipment, however are designed to work off 24V DC supply. High Efficiency DC/DC Conversion from 48 Volts to 24V DC is therefore necessary.
The APLAB High Efficiency, High Power DC/DC Converters are in wide demand to convert 48V station battery Voltage to 24V DC. Basic module is rated at 50Amps and has a built-in automatic current sharing feature to connect several units in parallel for higher current capacity upto 250 Amps. Different models need to be selected from the available range.
The system has modular design to meet DC load requirements from 50 Amps to 300 Amps in multiples of 50 Amps.
Analog meters are optionally provided for Display Output voltage and load current of each module. Status LED are provided for Output Over Voltage & Over Temperature.
 Technical Specifications
 Voltage  43.2V - 57.6V DC.
 Current No Load  1A typical at 48V.
 Current Maximum Load  30A typical at 48V.
 Input under voltage, over voltage turns off the unit, builds up automatically if recovered from abnormal condition.
 Voltage  24V DC (23V-28V settable by front panel potentiometer) 50 Amps max.
 Output Characteristic  CV, CC.
 Load Regulation  ±1% +Diode drop.
 Line Regulation  ±1%.
 Ripple  <200mV p-p.
 Efficiency  Better than 82%.
 Recovery Time  1ms typical.
 Over Voltage Protection  OVP  Electronic turn-off-reset through On/Off/Reset switch. Adjustable on front panel 24-33 (fixed 30V).
 Redundant Operation  Possible through built in D-diode.
 Over Temp. Protection OTP  Electronic turn off-reset through front panel On/Off/ Reset switch.
 Parallel Operation  Possible, unlimited.
 Operation in Series   Description of Signalling  Possible with option U (cross diode).
 Indicators and Controls  a) LED Green = Normal operation.
 b) LED Red = Over voltage.
 c) LED Red = Over temperature.
 d) On / Off / Reset switch = On & Off as well as Over Temp., over voltage reset.
 e) Potentiometer = Output voltage adjustment.
 f) Potentiometer = Over voltage protection adjustment.
 g) Analog meters for output voltage and current measurement (optional).
 Output falls below 85% of nominal voltage alarm by potential-free change-over contact-loadable with 220V/1A/40W.
 Operation Temperature  -10°C to +60°C.
Derating  2.5% / °C above +40°C.
 Storage Temperature  -20°C to +70°C.
 Humidity  90% without condensation.
 Cooling  By temperature controlled DC fan suction through front panel exhaust on the back.
 Switching Frequency  >60KHz.
 Electrical Compliance  VDE 0160/VDE 0804/VDE 0805 protection class 1.
 Isolation  Input/Output to Earth – 1400V DC.
 Mechanical Construction  19” sub unit = 4 unit high, 405 mm deep.
 Connectors  Brass terminals for Input/Output connection. 6 way terminal for sense, current share bus and alarm contact.
 Weight  Approx. 7 Kg.
 Input Over Voltage  The unit trips and automatically recovers under healthy input condition.
 Input Under Voltage  The unit trips and automatically recovers under healthy input condition.
 Input Reverse Polarity  Diode fuse combination.
 Inrush Current  NTC provided in series path of input.
 Output Short Circuit  Hiccup type characteristics.
 Overload  CC type.
 Output Over Voltage  Unit trips/can be reset manually thru’ reset switch provided on the front panel.
 Ability to Hot swap of Power Module.
Selection Guide
Input 'V'
Output 'V'
Load Current
Dimensions (mm)
W x D x H
No. of Modules
DDC 48/24/50
48V DC
24V DC
50 A
460 x 500 x 310
1 + 1
DDC 48/24/100
48V DC
24V DC
100 A
460 x 500 x 620
2 + 1
DDC 48/24/150
48V DC
24V DC
150 A
460 x 500 x 620
3 + 1
DDC 48/24/200
48V DC
24V DC
460 x 500 x 800
4 + 1
DDC 48/24/250
48V DC
24V DC
250 A
460 x 500 x 800
5 + 1