INFRASTRUCTURE
equipment to monitor electrical safety only makes up a small part of the overall cost of an operating room, but may be in use for up to 30 years. It may also be possible to install new equipment in addition to what is already in use. It is noteworthy that a proactive monitoring system decreases technical work and ensures that operations are not interrupted, which can result in significant cost savings.
Experience and collaboration The New Children’s Hospital in Helsinki, which is part of the joint municipal authority of the hospital district of Helsinki and Uusimaa (HUS), was completed in the autumn of 2018. In Finland, the treatment of demanding paediatric illnesses, such as cardiac surgery and organ transplantation, is centralised in this hospital. The starting point for the new
generation of equipment in this facility was to consider customer needs without compromising on technical durability or operability. An insulation fault positioning feature was requested for the international market, based on which the MEV-8 system was developed. This system monitors insulation failure and fault positioning, transformer overload and temperature and the continuity of protective earth. It also has three specified alarm outputs and remote monitoring panels are positioned in the operating room.
Unique monitoring for protective earth
(PE) grounding continuity, which complements and ensures continuity between the distribution board and the
The starting point for the new generation of equipment in this facility was to consider customer needs without compromising on technical durability or operability
last socket and the positioning of an insulation fault, can be implemented line specifically. The pulse measuring method also enables the monitoring of direct current (DC) networks, while an LCD display panel indicates active faults. The system can be set up easily using a Windows programme. The power network for the operating
room is separated from the electrical grid by a medical isolation transformer (IT system). The circuit feeding into the electronic device is insulated from the feeder network and its secondary circuit is not grounded. The isolation transformers ensure a constant supply of power and filter off any disruptions to the main grid. The leakage current is minimal and the first short circuit that occurs does not cause an outage. In other words, the isolation transformers provide the necessary protection while the system indicates any faults and sounds the alarm. Insulation monitoring relay measures
leakage from a floating isolated alternating current (AC) system to ground. The system uses pulse measurement and is therefore compatible with direct and alternating voltage networks. Pulse measurement also works well with modern switched mode power
supplies and indicates capacitive faults. A relay monitors measurement wires and transformer load/temperature. The system can be expanded with a module to monitor PE grounding continuity. The module separately monitors every fuse line and if there is an interruption in the protective earth (loose or damaged wire/contact), the maintenance team will be notified immediately. The module will also indicate which fuse line is faulty. For the maintenance team, there is a fault locator module, which will locate the fuse line with the insulation fault. In a fail situation, the system will communicate with the automation centre via relay contacts, which will inform the maintenance team of the fault. Early detection of a fault may prevent higher degradation of the device. In a worst case scenario, a faulty unit in open surgery may cause a deadly electric shock. Staff are provided with guidance on
how the system operates and guidelines are also attached to the wall of the operating room. If the alarm sounds, the faulty electronic device is unplugged from the socket and technical staff are notified. All medical devices used in grade two facilities must be connected to a network, which is insulated by isolation transformers. A separate socket may be available for cleaning and maintenance work, for example, in the operating room. The socket is directly connected to the national grid rather than to the insulated network. Medical devices must not be plugged into this socket as it must be used for its assigned purpose only, excluding any patient treatment. The socket must be clearly marked ‘not for medical devices’ or ‘maintenance socket’. A thorough commissioning inspection
Recovery room in the New Children’s Hospital with control panels for alarms and monitoring for PE continuity.
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must always be completed prior to the deployment of an insulation level monitoring system in new premises as well as in those under renovation. A commissioning inspection can only be conducted by a qualified electrician and it is recommended that the inspection is conducted by an IT system equipment supplier with an in depth knowledge of the system and related requirements. In the event of an insulation fault in a socket, the system will notify the hospital automation centre by relay, which will inform the maintenance team. An alarm also sounds and lights up in the operating room, where staff must disconnect the
IFHE DIGEST 2019
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