BN-15 Power Supply System provides uninterruptible 48V DC power supply for measurement, protection and control switchgear apparatus. It is built in a 380x380x210 mm cabinet or on a panel intended for installation in a bigger cabinet. The BN-15 consists of a rectifier / charger and a high frequency voltage converter, NAP-2 Power Unit, battery packs and automatic switches in power supply outputs. In normal operation, the high frequency converter supplies power for measuring, protection or control equipment and charges the batteries from an external 230V AC power supply. In the event of a 230V AC supply voltage failure, the power is supplied from the battery.

The NAP-2 unit is used for battery undervoltage and deep discharge protection. NAP-2 does not allow the battery to discharge below the safety level (according to battery characteristics) and switches off the battery via the K1 contactor when safety level is exceeded. When the external 230V AC supply is reestablished, NAP-2 recharges the battery.

In the DC distribution there are automatic switches (2 pcs) for the protection of individual power supply output, with auxiliary contact for remote signalling.