Insulation monitoring in operating rooms

In medical environments, the absolute reliability of electrical systems is of vital importance. Earth (grounding) leakages of electrical currents can occur in new and old electrical devices alike and, in the worst case, they can even cause death.

PPO-Elektroniikka Oy has created the MEV-7 Insulation Monitoring System to provide constant, safe and secure monitoring of electrical systems. It can provide the direct detection of the potential for insulation deterioration, such as the malfunction of the protective earth (PE-wire) or isolation transformers. The monitoring of operating conditions

is critical, as invisible parts of defective electrical equipment can cause dangerous situations. In hospitals, examples of such places and processes include; operating rooms; operation-preparation and postoperative premises; anaesthetic rooms; intensive care rooms; heart catheterisation facilities; arteriographic/angiographic rooms; and premature baby care rooms. If the preliminary conditions for a system malfunction begin to form in the electricity supply of the devices used in these critical environments, the insulation monitoring system immediately sets off an alarm, which helps prevent accidents at an early stage; saving money and even human lives. PPO-Elektroniikka Oy has supplied

more than 24 000 monitoring systems since the organisation was formed in 1981. And today, nearly all operating rooms in Finland use an MEV-7 or one of its earlier generations. Long before an electrical fault occurs, it

notifies personnel who can correct possible future insulation faults, such as the malfunction of PE-wires and isolation transformers. As a result, before insulation defects lead to a power failure they can be corrected, as personnel are alerted before a critical incident occurs. Due to the safety technology embedded in the system, sophisticated and expensive equipment, and the people around it can be saved from harm and work more efficiently. In addition, it allows the advance planning of fault repairs, to allow maintenance to become less reactive. Insulation monitoring


systems are required in operating rooms and similar Class II medical premises in all countries in the European Union, due to the regulations stipulated in the EC Directives 89/336/EC and 1999/5/EC and the EU Directive 2004/108/EC. In Finland, monitoring systems of this type have been mandatory, and in use, since 1983. Leakage of electrical current can occur

in both new and old electrical devices. During surgery a leakage in the operating equipment or other electrical equipment can be dangerous for both for the patient and the surgical staff. PPO-Elektroniikka Oy’s solution is to

separate the operating room equipment from the primary power system with an isolation transformer system which then monitors the electrical devices connected after that transformer.

Timo Ohtonen

Timo Ohtonen is Managing Director and owner of PPO-Elektroniikka Oy. He was one of the company’s

founders in 1981 and has extensive experience in professional

electronics and electrical safety.

PPO-Elektroniikka Oy is a member of the Association of Finnish Hospital Engineering.

The company developed the solution

specifically for use in healthcare facilities and operating rooms in hospitals, and its products are internationally approved by medical authorities. The insulation-level monitoring unit is

a programmable unit that monitors for current leakage (earth leakages) in the network and is situated after the isolation transformer. If it detects a leakage, it sets off an alarm. The unit also looks for signs of overloading and overheating in the isolation transformer. If it senses these situations it activates an alarm. Two potentially free relay contacts are produced: one for the overloading/ overheating of the isolation transformer, and another one to control the condition of the insulation level and PE-wires. These signals can be to a remote alarm centre, control room, or a maintenance centre. Different lights are used to allow users to differentiate between a low insulation level and isolation transformer incident. The LC-7 line monitoring device

monitors for broken, disconnected, and loosely connected PE-wires in the power sockets and installed equipment. It uses a light signal to indicate the particular faulty line. The EV-7 insulation-level monitoring

panel is placed in the handling room (for example, in the operating room) to inform


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