GE MiCOM P40 Agile Technical Manual

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Contents

P44x/EN IN/Hb6 Installation(IN) 14-6 MiCOM P40 Agile P442, P4442 HANDLING OF ELECTRONIC EQUIPMENTA person’s normal movements can easily generate electrostatic potentials of severalthousand volts. Discharge of these voltages into semiconductor devices when handlingelectronic circuits can cause serious damage which, although not always immediatelyapparent, will reduce the reliability of the circuit. This is particularly important to considerwhere the circuits use complementary metal oxide semiconductors (CMOS), as is the casewith these relays.The relay’s electronic circuits are protected from electrostatic discharge when housed in thecase. Do not expose them to risk by removing the front panel or printed circuit boardsunnecessarily.Each printed circuit board incorporates the highest practicable protection for itssemiconductor devices. However, if it becomes necessary to remove a printed circuit board,the following precautions should be taken to preserve the high reliability and long life forwhich the relay has been designed and manufactured.1. Before removing a printed circuit board, ensure that you are at the same electrostaticpotential as the equipment by touching the case.2. Handle analogue input modules by the front panel, frame or edges of the circuitboards. Printed circuit boards should only be handled by their edges.Avoid touching the electronic components, printed circuit tracks or connectors.3. Do not pass the module to another person without first ensuring you are both at thesame electrostatic potential. Shaking hands achieves equipotential.4. Place the module on an anti-static surface, or on a conducting surface which is at thesame potential as yourself.5. If it is necessary to store or transport printed circuit boards removed from the case,place them individually in electrically conducting anti-static bags.In the unlikely event that you are making measurements on the internal electronic circuitry ofa relay in service, it is preferable that you are earthed to the case with a conductive wriststrap. Wrist straps should have a resistance to ground between 500 kΩ to 10 MΩ. If a wriststrap is not available you should maintain regular contact with the case to prevent a build-upof electrostatic potential. Instrumentation which may be used for making measurementsshould also be earthed to the case whenever possible.More information on safe working procedures for all electronic equipment can be found inIEC 61340-5-1. It is strongly recommended that detailed investigations on electronic circuitryor modification work should be carried out in a special handling area such as described inthe aforementioned Standard document.