In the beginning of 2020, Bender was contacted to test the Isolated Power Systems (IPS) that were used to provide power to nine operating rooms in two large Canadian hospitals. The panels required testing because the associated Line Isolation Monitor (LIM) that was monitoring the IPS was not responding to any tests. Several of the existing LIMs were outdated and nuisance alarms were occurring frequently, causing disruptions to patient care and interrupting hospital personnel’s busy schedules. In order to diagnose what was causing these nuisance alarms, a Bender technician went to the site to investigate.
After testing the panels as per CSA Z32 recommendations, it was noted that there were quite a few issues with the installation and the receptacles being fed by the IPS, as well as with the LIMs themselves. A few receptacles had polarity issues that were causing incorrect readings. The receptacle retention force that was meant to keep a plug in place was lower than the requirements stipulated in the CSA Z32 standard. This could potentially cause the plug to fall out inadvertently or not make a connection to the power it required to remain functional.
The existing LIMs that were connected to the IPS were old units that had exceeded their recommended lifecycle for being in operation (Image 1). Since the LIMs contain electronic components and are in operation 24/7, there is a lifespan associated with their internal circuits and, therefore, need to be checked annually. Some of the LIMs had trouble responding to bolted ground faults, resistive faults, and some failed to alarm entirely on the danger that was simulated into the system by the Bender LT3000 tester. For many of the ORs in these hospitals, it meant that the IPS was supplying power but not being monitored as needed, posing a safety risk to the staff and patients within the operating rooms.