ENI-SBT70 Power supply unit

Stanowisko ENI-SBT70
Stanowisko ENI-SBT70



The ENI-SBT70 power supply unit with a rated output voltage of 600 VDC is intended as a power supply to tram cars during testing of onboard electrical components. The power supply unit features a wheeled base for easy mobility.


 Supply voltage  3 x 400 VAC, 50 Hz
 Output voltage  400 / 600 / 750 VDC
 set with a selector switch on the cabinet front
 Rated power output  70 kW
 Overload capacity  30% up to 30 s
 Cooling  forced air (the fan starts above 70°C of the rectifier temperature)
 Protection rating  IP 23
 Ambient temperature  0 to 40°C
 Weight  ca. 480 kg
 Size [L x W x H]  650 x 1000 x 1380 mm


The power supply unit is built within a cabinet enclosure with the interior accessible from the front, beneath single doors. The transformer and the cabinet structure are mounted on a steel base plate suspended on two fixed wheels and two castors. This increases the mobility of the device. The bottom right-hand part of the cabinet enclosure features the terminal box. The front doors display the output current and voltage meters, and a basic suite of control and monitoring instruments:

  • Main switch,
  • ON button,
  • OFF button,
  • 400-600-750 VDC output voltage selector switch,
  • Emergency stop device button,
  • FAULT indicator lamp.

At the left-hand wall of the cabinet is a heat sink with bolt-on diode modules of a 6D rectifier, a main line contactor, and a transformer precharging relay. The back wall features a second heat sink with precharging resistors. The left-hand side wall of the cabinet carries an air vent grille for the device enclosure box. This vent ensures an efficient flow of air within the cabinet enclosure. The back wall carries an air exhaust fan. The ventilator is turned on when the rectifier heat sink temperature exceeds 70°C.


The power supply unit adjusts the 3 x 400 VAC supply voltage to the preselected value (400 / 600 / 750 V) with the transformer taps, which are switched with the selector on the cabinet front. The transformer provides galvanic separation and adjustment of voltage. The transformer downstream voltage is rectified by the 6D rectifier.

Power kW
Input voltage
3 x 400 VAC
Output voltage
600 VDC

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