The Importance of Insulation Monitoring Devices
Insulation Monitoring Devices (IMD’s ) are indispensable tools in the field of electrical safety. They play a crucial role in preventing electrical accidents, protecting equipment and ensuring continuity of operations across various industries. IMD’s are designed to continuously monitor the insulation resistance and thus prevent electrical faults from occurring. In an IT (ungrounded) network, the first insulation fault may go unnoticed as it does not cause an immediate system failure. However, if a second insulation fault occurs, it can lead to a large-scale ground fault, causing significant damage to the electrical system and posing a serious safety risk. IMD’s are designed to detect these initial failures and allow for preventive actions before a catastrophic failure occurs.
How does the AKTIF Insulation Monitoring Device (IMD30) Work?
IMD30 is connected between life conductors (phase conductor and neutral) and earth (PE conductor). It produces a DC voltage signal that is superimposed on top of the AC voltage of the system. This DC voltage is used to measure the insulation resistance.
When the insulation is intact, the resistance is high, and only a small amount of current flows from the living conductors to the ground through the IMD30. However, if an insulation fault occurs, the resistance decreases and the current flow increases. IMD detects this change in current flow and triggers an alarm.
The alarm threshold is set at a level of < 50kΩ (based on IEC-standard 61557-8) that allows the early detection of insulation faults and provides sufficient time for preventive action before a second fault occurs and causes a full-scale ground fault.
When the insulation fault is recognized, IEC-standard 60364-4-410 says that this first fault has to be eliminated within shortest practicable time.
If you want to search for the cause of the first fault manually it will take very long, especially in an Intensive Care Unit (ICU) with several beds or a large Operating Room (OR). The EDS30 is “The Unit” you look for as it can detect and locate the defective circuit within seconds.
In case you have two supplying lines feeding the insulation transformer the required product is the CTS30 – it’s a changeover-unit that is far better than the IEC-standard which asks for less than 100ms change-over time – CTS30 will do it in less than 50ms in combination with 2 standard contactors. There is no need or requirement in the standards to invest far more money in special industrial safety levels like SIL2 which is offered by some competitors. Those are not required for medical applications !
Insulation Monitoring Devices Usage Areas
The IMD’s are used in “Group-2-Rooms” in hospitals and other healthcare facilities. The “Group-2-Rooms” are for example: Operating Room, Catheterization Labs, Intensive Care Units (N)ICU, Premature baby rooms, Haemodialysis room, EEG-Rooms, Emergency Rooms, Cardiac Care Units CCU
These systems are designed to ensure the safety of patients and staff by preventing electric shocks in the event of an isolation fault.
Remote or Local Alarm Units / Control Panels
With the installation of IMD30, CTS30 and EDS30 alone the monitoring system is not complete. The nurses and doctors in the OR/ICU need to know about the problem even when they can continue to work like before. The important point is that the maintenance staff knows / learns about the problem as soon as possible and can take immediate action. That is why the Isolated Power System has to be installed outside of the monitored room(s).
AKTIF’s solution for the information of nurses / doctors and maintenance staff are the Local Alarm Panel LAP70, the Remote Alarm Indicator RAI70 and various Operating Room Control Panels OCP (for example our OCP21G).
Whenever you want to know more about these products or need individual help with the configuration, please feel free to contact us.
