Power Requirements
Imaging equipment power demands span three orders of magnitude — from a 20A C-arm circuit to a 200+ kVA linac service. Power quality matters as much as capacity — imaging electronics are sensitive to voltage sag, surge, and harmonic distortion.
Equipment power demands
- MRI — 3-phase 400 / 480V, 100+ kVA service. Cold-head compressor + gradient amplifier (GPA) + RF amplifier + host computer combined.
- CT — 3-phase 480V, 150–200 kVA. Tube ramp-up demands brief high peak power.
- Linac — 3-phase 480V, 200+ kVA. Klystron / modulator / waveguide systems plus control / imaging chain.
- PET / CT — combined CT + PET-electronics + ancillary load.
- Cath lab / interventional — 3-phase, 50–100 kVA depending on detector size and biplane vs single-plane.
- Fluoroscopy / DR — single-phase or 3-phase, typically under 50 kVA.
- Mammography — single-phase or 3-phase, ~20 kVA.
- C-arm (mobile) — single-phase, 20A dedicated circuit (mobile units are battery-powered for the actual exposure but charge from wall power).
- Mobile DR — single-phase, 20A dedicated; lithium battery-powered for mobile use.
- Ultrasound — typically standard outlet; single-phase 110V.
Power quality
- Voltage stability — imaging electronics are sensitive to voltage sag (brown-out) and surge. Dedicated transformer for critical imaging rooms is the typical approach in modern installs.
- Harmonic distortion — high-power imaging equipment can introduce harmonic distortion back into the building electrical system; isolation transformer mitigates.
- Power-factor correction — required by some utilities at high-load installs; OEM-spec.
- Grounding — single-point grounding to specified resistance is a common OEM requirement.
- UPS — for critical workflows, equipment-specific UPS provides orderly-shutdown bridge.
Emergency power
Hospital imaging equipment is often on emergency generator; load calcs must include imaging equipment in generator sizing. See Emergency Power for detailed coverage. MRI cold-head compressor on emergency power is a meaningful spec — extended outage without compressor power risks helium boil-off.
Refurb / relocation gotchas
- Older facility electrical infrastructure may not match new equipment's power-quality demands; transformer / panel upgrades are common refurb-deal line items.
- Equipment-room layout changes (transformer relocation, distribution-panel modification) can be substantial cost on relocations.
- Power-quality survey before install catches issues — a refurb installed into a marginal power environment surfaces intermittent faults months later.