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An interesting history for isolated power systems

Al Rufaie, a medical electrical consultant with over 40 years’ experience in the electrical industry, takes a look at the history and international development of medical IT (isolated power) power systems.

Patients undergoing acute care in healthcare establishments (such as hospitals) require enhanced reliability and safety of the electrical installation, as well as safe and reliable operation of the medical electrical (ME) equipment used. These criteria need to be met both to ensure security of supplies, and to minimise the risk of electric shock. In medical locations, the risk to patients is increased, due to:

The presence of liquids, such as blood and saline solutions, will also add to the risks, due to an increased conductive area, and subsequent lower body resistance. Any prolonged loss of the mains supply to life-supporting ME equipment may put the patient’s life at risk. This equipment must have secure supplies to provide adequate safety.

The introduction of medical IT, or, as they are also known, isolated power systems, has eliminated the operational hazards listed above. Earth fault currents in a medical IT system depend only on the capacitive coupling between the line conductors and earth. As these capacitances are quite low in value, the resultant capacitive coupling current is quite low, i.e. not dangerous.  Similarly, a single earth fault will not cause a trip; it simply creates a reference to earth (as in a TN system), so continuity of supply is present.

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Upcoming Events

The Fire Safety Event

NEC, Birmingham
25th - 27th April 2023

Facilities Show

ExCeL London
16th - 18th May

NAHFO Conference 2023

Crowne Plaza, Stratford-upon-Avon
5th - 7th June 2023

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Manchester Central
10th - 11th October 2023

Access the latest issue of Health Estate Journal on your mobile device together with an archive of back issues.

Download the FREE Health Estate Journal app from your device's App store

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