Micom P721, Техническое руководство

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P72x/EN IN/C21 Handling, Installation and Case Dimensions
Page 4/10 MiCOM P721/P723
2. HANDLING OF ELECTRONIC EQUIPMENT
A person’s normal movements can easily generate electrostatic potentials of several
thousand volts. Discharge of these voltages into semiconductor devices when handling
electronic circuits can cause serious damage, which often may not be immediately apparent
but the reliability of the circuit will have been reduced.
The electronic circuits are completely safe from electrostatic discharge when housed in the
case. Do not expose them to risk of damage by withdrawing modules unnecessarily.
Each module incorporates the highest practicable protection for its semiconductor devices.
However, if it becomes necessary to withdraw a module, the following precautions should be
taken to preserve the high reliability and long life for which the equipment has been designed
and manufactured.
1. Before removing a module, ensure that you are at the same electrostatic potential as
the equipment by touching the case.
2. Handle the module by its frontplate, frame or edges of the printed circuit board. Avoid
touching the electronic components, printed circuit track or connectors.
3. Do not pass the module to another person without first ensuring you are both at the
same electrostatic potential. Shaking hands achieves equipotential.
4. Place the module on an antistatic surface, or on a conducting surface which is at the
same potential as yourself.
5. Store or transport the module in a conductive bag.
If you are making measurements on the internal electronic circuitry of an equipment in
service, it is preferable that you are earthed to the case with a conductive wrist strap. Wrist
straps should have a resistance to ground between 500k
Ω
– 10M
Ω
.
If a wrist strap is not available you should maintain regular contact with the case to prevent a
build-up of static. Instrumentation which may be used for making measurements should be
earthed to the case whenever possible.
More information on safe working procedures for all electronic equipment can be found in
BS5783 and IEC 147-OF. It is strongly recommended that detailed investigations on
electronic circuitry or modification work should be carried out in a special handling area such
as described in the above-mentioned BS and IEC documents.