The box P, has the function of electrically connecting the satellite with its various subsystems. The primary tension comes from the solar panels, and it is nominally 27 V (between 24 and 34 V). Starting from this, the box P provides three different tensions, two for the analog part (+6V, -6V) and one for the digital (+5V), totally independent.
The ignition of P box and so NINA switching ON is realized by telecommand. For redundancy reasons, there are two independent systems of secondary power-supply, again selected by telecommand. The status of the box P during the flight is monitored by 8 signals (4 for any of the two power-supply systems), that take under control currents and temperatures inside the box.
A sketch of the power supply distribution inside the instrument is shown in Figure 1.