The isolated power grid is a particular type of power distribution used in critical care areas of hospitals; this kind of grid protects patients and medical staff from the dangers of electric shock as a result of leakage currents (micro shocks) during certain medical procedures.
As part of their operation, Isolated energy systems are powered by an isolation transformer, which is capable of eliminating the neutral ground reference. Therefore, it operates without grounding, so unlike ground fault circuit interrupters, hospital isolated power grids don’t trip or shut down power to essential medical equipment when a ground fault occurs.
Can electrical network problems be identified if equipment continues to function normally?
Unlike ordinary power systems where tests such as Murray loop testing, Varley loop testing, or ground overlap testing are performed; Insulated power systems have an online insulation monitor that continuously measures the line-to-ground impedance of isolated lines conductors.
A system’s hazard current is inversely proportional to the ground impedance, so the online insulation monitor calculates and displays the total hazard current for this system. When THC exceeds 5 mA, a visual and audible alarm is triggered to warn of a first failure in the system.
As a result, a fault current could begin to flow through the system, if a secondary fault occurs, providing an alternative path for this current. In the event of the alarm activating, it does not mean that dangerous fault currents have occurred, only that the protection layer has been compromised, and now there is a possibility that a failure may occur.
For this reason, automatic fault location systems generally have real application until after the procedure is finished and the manual revision protocol, since it is not possible for safety to intervene in the isolated power system in its full operation with associated patients.
What should the medical team do when the line isolation monitor goes off?
Alarms do not indicate imminent danger; therefore, medical procedures should not be interrupted, as this can pose additional risks for patients; therefore, medical personnel must complete the procedure and remove the patient from the area.
Once this is done, those in charge of the hospital’s isolated power network should look for the source of the failure, try to identify a solution, and ensure that the equipment functions as it should and that patients and medical staff are safe ensuring everything works for future procedures.
In 90% of cases, performing a safe Root-Cause check on an isolated power system manually takes less than 40 seconds, and the remaining 10% takes between 40 seconds and 2 minutes.
We at IASS engineering are authorized as distributors for PG LifeLink, one of the most innovative hospital isolated energy products manufacturers. We are qualified to install and maintain isolated energy networks based on our knowledge and experience. Feel free to contact us!