Emergency Power
Critical imaging rooms (ED CT, trauma CT, cath labs, linacs, ICU portable workflow) are typically on hospital emergency power — generator-backed circuits that maintain operation through utility-power loss. Equipment selection and emergency-power sizing are coupled decisions during install planning.
Typical tiers
- UPS (uninterruptible power supply) — seconds-to-minutes bridge for orderly shutdown or transition to generator. Sized to the full equipment load for the duration of generator startup.
- Generator — minutes-to-hours bridge for continued operation. Hospital generator load calcs must include imaging equipment in sizing.
- Dual feed — premium installations have redundant utility feeds for additional resilience; rare in community hospitals.
- Equipment-specific UPS — some platforms ship with built-in UPS for orderly shutdown of the imaging chain (CT consoles, linac control systems, MRI host computer).
Modality-specific considerations
- CT — modern scanners need clean power for tube ramp-up; UPS-protected console + generator-backed scanner power is typical.
- MRI quench during power loss — magnet stays energized (superconducting), but cryocooler needs power. Extended outage → helium boil-off → cryogen loss if cryocooler down for hours-to-days. Cold-head compressor on emergency power is a meaningful spec.
- Linac — emergency power keeps the linac control system orderly through utility loss; klystron / magnetron typically does not run from emergency power. Treatment continuity is not an emergency-power scenario for therapy linacs.
- Cath lab — full operation on emergency power is essential for STEMI / stroke / trauma response. The room must be designed to stay operational through utility loss.
- PET / CT — generator-backed for the imaging chain; hot lab on emergency power for radiopharmaceutical handling.
Common gotchas
- Generator load-shedding during simultaneous high loads — refurb installs with higher-than-predecessor power draw can push the hospital generator over capacity.
- UPS battery aging — lithium / lead-acid banks degrade on a 5–10-year cycle; routine load-test discipline matters.
- Transfer-switch testing — monthly transfer test is hospital standard; equipment must tolerate the brief transfer event.
- Refurb relocations — confirm emergency-power coverage at the new location matches the original room.