Medical device galvanic isolator EVM-105-240 series

Line Isolation and Overload Monitors (LIOM) enables the integrity of the Isolation Transformer to be monitored and an alarm raised to warn of impeding danger if an impedance occurs between any part of the isolated supply and earth The LIOM simultaneously measures the impedance between both of the lines and earth and calculates the “worst case” current that would flow through that line with the higher impedance should the other line then become shorted to earth by a second fault The current that would flow if that second fault occurs is known as the Prospective Hazard Current (PHC) Should the PHC exceed the preset level of 5mA, then an audible and visual alarm will occur, but the supply will not be interrupted If this alarm occurs, the medical staff can in light of the patient’s condition, choose to continue with the procedure, bearing in mind that it is only a prospective hazard. Measures can however be taken by the medical staff to rectify the situation by disconnecting all non-essential equipment from the system, one of which may be causing the problem In addition to monitoring isolation, LIOM’s are required to continuously monitor the total current being drawn from the transformer to prevent an overload situation occurring. Again, this is a warning system and does not cause an interruption to supply. Obviously if short circuit conditions occur then a circuit breaker supplying the primary of the transformer will prevent serious damage occurring