Rack-mount Switchmode Power  Supply System S3000 v4 is designed  for power supply of telephone  exchanges and other telephony  devices where highest performances  concerning interferences, noise and  response rate.

    The system is fully automated and  capable for uninterrupted,  independent operation, which is why  it is suitable for use in the battery  systems maintenance, remote sites  and power supply of other  consumers with DC current and  voltage. The system is homologated  by the communities of Yugoslav and  Russian PTTs.

S3000 version 4 is manufactured in three standard versions, S1, S2 and S3  depending on the size. Nominal output voltage is 48V and the nominal  current is 100A in version S1, 200A in version S2, and 400 and 800V in  version S3. Upon request the system can be produced for other standard  values  of the nominal DC voltage 24V, 60V or 110V. The system can operate  with or without accumulator batteries, diesel generator or other auxiliary  power  supply.


    System input in normal operation mode is three-phase (or mono-phase) AC  voltage. In the rectifier modules the input voltage is converted through DC-DC  converter and stabilized to the desired value of DC output voltage. Battery  voltage Ub is programmed according to the temperature and battery type.
    The system supplies current for the consumer, under maximum load, and  also current for battery maintenance. Distribution voltage (on consumer) Ud is  practically equal to the battery voltage Ub, the difference is negligible, and  equals the voltage drop on the system adder. The total system load is equally  divided to all operating rectifiers. The distribution of current to the rectifier  modules is within the limits of 3%. If the load per rectifier is too small the  system automatically switches off a certain number of rectifiers ("stand-by"  regime). Rapid load changes are compensated from the resources of the  active rectifiers, and if it is bigger than their current capacity, for a short  period they are compensated from the battery until the switch-on of the  necessary number of "stand-by" rectifiers.
    The rectifiers' currents are following consumption variation, maintaining  steady output voltage. On the central processing module - MDP through  keyboard and display (LCD and LED), system operation control is performed,  indication and detection of errors, and also measurement of current and  voltage of batteries and distribution units, mains voltage, system parameters,  rectifiers parameters. The user chooses the system parameters depending on  the type and capacity of the batteries and the exploitation conditions.

Operation Upon Failure of Mains Supply

   In the case of complete failure of the mains supply or mains voltage  instability  (out of the permissible limits of 176V - 253V), rectifiers are switched  on, and the consumer is supplied completely by the battery. Battery voltage  drops during time, so the consumers supplied with this kind of system  configuration must have the possibility of operation within a wide input range  (40.5V to 57 V). If the battery voltage drops below the permissible level, the  alarm is generated, and in the case of further drop, the consumer is switched  off. When the mains voltage is recovered or stabilized, the rectifiers are  switched on automatically and they take over the load and recharging of the  battery.

Operation with Reduced Resources

  Complete failure of mains supply is the most frequent mains failure, but  malfunction of a single or two phases can happen, too. In case of failure of  one (two) phase, the system preserves steady output voltage, but its maximum  output current drops to 2/3 (1/3) of nominal output current. Apart from mains  failure, failure may happen on any of the rectifiers. In that case the maximum  output current is reduced proportionally to the ratio of the number of  inoperable and operable rectifiers. If during one of the above mentioned  system failures the consumption is lower than the output power of the  rectifiers, the system operates as if it were in normal operating mode. If the  consumption is higher than the output power of the rectifiers, the system  operates with the maximum output power available, and the remainder of the  current required is taken from the accumulator batteries. This mode of  operation is continued until the failure is removed.

Operation Upon Mains Supply Reinstatement

    Upon mains supply reinstatement, the rectifiers are switched on  successively in 60 seconds intervals in order to stabilize the AC network, and  they supply current for batteries recharging. The recharging current is  controlled and limited, depending on the type and capacity of the batteries.  When battery voltage reaches the maintenance voltage, the current drops.  After the current reaches the lower threshold, the battery voltage is set to  floating voltage (depends on temperature and battery type) - recharging is  stopped and rectifiers return to normal mode. The batteries recharging mode  lasts up to 14 hours.


Number of rectifier units: S1 up to 4, S2 up to 8 and S3 up to 32

Input data
Mains voltage 220/230 Veff
Mains frequency 47-63 Hz
Permissible voltage variation per phase -15% to +10%
Permissible distortion per phase 30%
Input voltage under full load and nominal input voltage 4 x 7A
Input current THD < 20%
Inrush current for all three phases S1 < ( 4 x 8A)
S2 < ( 8 x 8A)
S3 < (32 x 8A)
Power factor cosj > 0,99
Input fuse for each rectifier 10A
Protection overvoltage, undervoltage, fuse, atmospheric discharge
Output data  
Nominal voltage 48V
Maintenance voltage adjustable 49-56V
Recharging voltage adjustable 52-58V
Stability better than 1%
Nominal current 4 x 25A; 8 x 25A; 32 x 25A;
Current limitation 4 x 26A; 8 x 26A; 32 x 26A;
Output power 4 x 1400W; 8 x 1400W; 32 x 1400W;
Response time 1ms
Voltage impulse amplitude < 2Vp-p
Psophometric voltage noise without battery < 1mVeff
Effective noise value 10Hz to 450kHz < 25mV
Broadband noise < 10mVeff/MHz
Protection on each rectifier overvoltage, undervoltage, overcurrent, short circuit
General data  
Processor management RS 485 interface
Operating frequency of module 50 kHz
Permissible ambient temperature 0C to + 40C
Permissible storage temperature -10C to + 70C
Permissible humidity up to 90%
Distribution unit fuses highperforming meltable
Battery fuses highperforming meltable
Temperature protection 69C
Undervoltage protection of batteries adjustable
Indicating instruments digital 1%
Signalization sound, light and remote alarm
Spare parts 20 years
Warranty 3 years
Outer dimensions
Height 450mm
Width 632mm
Depth 500mm