# UPS (uninterruptible power supply)

Open Critical Care, in an answer by Assist International, advises a small 1 kW UPS (uninterruptible power supply), a battery-backed power unit, feeding the control circuit and PLC of a PSA oxygen plant, and calls it inexpensive protection.

PATH and CHAI (July 2021) list generators or an uninterruptible power supply as back-up power sources that can help provide oxygen from concentrators during power outages, and the WHO-UNICEF technical specifications for oxygen therapy devices (14 January 2019) say a concentrator needs a continuous AC power source, such as solar power, battery, or mains electricity with or without backup, for example a generator, UPS or battery.

In another FAQ answer, Open Critical Care says that a UPS with online double conversion can also provide voltage stabilisation and protection for sensitive equipment, and advises checking the voltage and frequency of the device and the power supply: a 110 V 60 Hz UPS may not charge its internal batteries if supplied at 110 V 50 Hz.

For the plant as a whole, UNDP's requirements (effective 1 January 2025) say a PSA plant requires reliable, continuous primary and backup power supply sources, and PATH and CHAI (2021) say a backup supply such as cylinders is required to maintain oxygen flow in case of a power outage or mechanical failure. ULTRAOX plants can be connected to a diesel-electric generator, according to the ULTRAOX datasheet (2022).

## Sources

- [Open Critical Care Oxygen FAQ (answer by Assist International): Is it advisable to have UPS as well as generators for a PSA plant?](https://opencriticalcare.org/faq/is-it-advisable-to-have-ups-as-well-as-generators/)
- [Open Critical Care Oxygen FAQ: What are common power related challenges and workarounds in resource-variable settings?](https://opencriticalcare.org/faq/what-are-common-power-related-challenges-and-workarounds-in-resource-variable-settings/)
- [PATH and CHAI, Oxygen Generation and Storage: Oxygen Concentrator (July 2021)](https://media.path.org/documents/O2_generation_and_storage_oxygen_concentrators_v2.pdf)
- [WHO-UNICEF, Technical specifications and guidance for oxygen therapy devices (14 January 2019)](https://www.who.int/publications/i/item/9789241516914)
- [UNDP, REQ-OXY-001 v01, Technical and regulatory requirements for oxygen plants (effective 1 January 2025), section 6.4](https://healthimplementation.undp.org/wp-content/uploads/2025/01/REQ-OXY-001-v01-UNDP-TECHNICAL-REGULATORY-REQUIREMENTS-FOR-OXYGEN-PLANTS.pdf)
- [PATH and CHAI, Oxygen Generation and Storage: Pressure/Vacuum Swing Adsorption Plant (July 2021)](https://media.path.org/documents/O2_generation_and_storage_PSA_VSA_v1.pdf)
- [ULTRAOX datasheet (2022), p. 9](https://www.ultracontrolo.com/ultraox)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/glossary/ups/