What power supply does a PSA oxygen plant need?

WHO, Foundations of medical oxygen systems (2023), says a PSA plant must be connected to a reliable and continuous source of energy for all intended hours of operation, with main and backup sources. It asks for cables for each component, a power cabinet with surge and earth protection and an inbuilt phase controller for three-phase devices, and for electrical elements to be compatible with the power source, with the frequency, voltage and plug type specified. Voltage fluctuation, WHO notes, will cause damage to the unit.

The 2020 WHO interim specification for PSA plants (superseded by WHO's technical specifications of 31 December 2024), from its COVID-19 (2019-nCoV) series, which stated that it would expire two years after publication, listed 380 VAC ± 15%, three-phase, 50 Hz for plant operations and 220 VAC ± 15%, single-phase, 50 Hz for the control system, noting that voltage, frequency and plug vary between countries, with electrical protection by resettable circuit breakers or replaceable fuses in both neutral and live lines.

Sizing the supply

WHO (2023) asks the supplier to provide an electrical requirements chart with the starting current, minimum protection current and load curve, and notes that the power load differs between single and multiplex plants and with or without a cylinder filling station. The Global Fund (4 March 2025) warns that large PSA plants can have high compressor in-rush currents, for which the generator and switchgear must be sized, and its sustainability guidance (22 August 2024) asks for properly balanced three-phase power, reliably sized cables, protection from voltage fluctuation and appropriately sized backup power. Its commissioning guideline (28 August 2024) checks the supply voltage on all phases and that backup power meets start-up and running loads and has the same phase rotation as the primary supply.

Essential supply and resilience

NHS England guidance, HTM 02-01 (2026), says all components of a PSA supply system should be connected to the essential electrical supply, with a separate power supply and subcircuit for each compressor and vacuum pump and separate power supplies for the duty and standby sieve assemblies, taken from the same phase. AIGA 113/20, adopted from EIGA Doc 195, requires a back-up electrical supply such as an emergency generator and sets the level of isolation between the supplies of the primary and secondary sources by risk management.

In ULTRAOX plants

The ULTRAOX datasheet (2022) asks the customer to provide the three-phase electrical supply and states that the plant can be connected to a diesel-electric generator. Its ULTRASCREW compressor motors are 400 V, three-phase, 50 Hz, IE3, IP55, with star delta starting, and the ULTRASEC dryer table lists single-phase 230 V for models USL 1 to USL 15 and three-phase 400 V, 50 Hz for USL 16 to USL 39. The ULTRACECO SC compressor table gives motors for 50/60 Hz, 208 to 440 V, and the ULTRACECO HP filling compressor datasheet lists a three-phase motor for 50/60 cycles.

The ULTRAOX ST table lists compressor power from 2.2 kW for model 3 to 220 kW for model 1640, noting that compressor power and pressure can vary with the service conditions of the facility.