## 5 Surface Auxiliary System
### RCUPS System  
The RCUPS system was composed of diesel generators, an uninterruptible power supply (UPS), Iridium satellite communication, and a control system, all these elements were integrated into two customized 4 m-long containers (Figure 8).  
One of the containers serves as the generator cabin, which is mainly designed to accommodate two diesel generators, a 400 L fuel tank, a 500 L engine oil tank, and a set of control systems. The generator set employed a Hatz 4H50 TI diesel engine to drive the Leroy Somer LSA42.3 L9 generator, which is produced in Nidec Corporation, Angouleme, France and can deliver a net output power of 28.7 kW at 1500 RPM, with an output voltage of 220 V. The two generators operate in an interactive manner. In case of a generator failure or when maintenance is needed, the AGC (Automatic Generation Control) controller disconnects the faulty generator from the UPS system and activates the other generator. Under normal operating conditions, the two generators were automatically rotated every 100 h by default.  
The 400 L fuel tank directly supplies fuel to the generators and is equipped with four fuel-level sensors. When the fuel level falls below 20%, the fuel pump automatically transfers fuel from the external tank to the daily-use fuel tank until the fuel level reaches 80%. Under full-power operation, the diesel generator consumes fuel at a rate of 9 L/h. Consequently, approximately 39.5 m\({}^{3}\) of fuel and 400 L of engine oil were required for six months of operation.  
The other container was designated as the instrument cabin and was primarily intended to accommodate the high-power UPS and Iridium satellite communication system. A Santak ARRAY MP series modular UPS, featuring a rated output power of 24 kW and a power factor of 0.8, was selected to stabilize the generator voltage and provide power  
Figure 8: RCUPS system: (**a**) 3D model; (**b**) top view of RCUPS system; (**c**) AGC controller in generator cabin; (**d**) two diesel generators; (**e**) high power UPS.  
to the entire EFSOS system during generator rotation. The UPS batteries can support the system for up to half an hour under an 18 kW electrical load.  
The two containers were connected via an air duct. The temperature control system employed fans to facilitate air exchange between the two containers, effectively utilizing the waste heat from the generator to warm the instrument cabin. The heat exchange system operates under three control modes: (1) when the temperature difference between the two containers exceeds 6 \({}^{\circ}\)C, the heat exchange system starts and then stops operation when the temperature difference falls below 2 \({}^{\circ}\)C; (2) when the temperature in the generator cabin exceeds 20 \({}^{\circ}\)C, the heat exchange system starts and then halts when the temperature falls below 10 \({}^{\circ}\)C; (3) when the temperature falls below 0 \({}^{\circ}\)C, four sets of electric heaters are activated to heat both the generator cabin and the instrument cabin, and heating stops once the temperature reaches 10 \({}^{\circ}\)C. Through this method, the temperature inside the two containers can be maintained above 0 \({}^{\circ}\)C in the extremely cold environment of Antarctica.