Technical Guide P92x/EN GS/E11
Getting Started
MiCOM P921-P922-P923 Page 3/18
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1. GENERAL CONSIDERATIONS
1.1 Receipt of relays
Protective relays, although generally of robust construction, require careful treatment
prior to installation on site. Upon receipt, relays should be examined immediately to
ensure no damage has been sustained in transit. If damage has been sustained
during transit a claim should be made to the transport contractor and AREVA
should be promptly notified.
Relays that are supplied unmounted and not intended for immediate installation
should be returned to their protective polythene bags.
1.2 Electrostatic discharge (ESD)
The relays use components that are sensitive to electrostatic discharges.
The electronic circuits are well protected by the metal case and the internal module
should not be withdrawn unnecessarily. When handling the module outside its case,
care should be taken to avoid contact with components and electrical connections. If
removed from the case for storage, the module should be placed in an electrically
conducting antistatic bag.
There are no setting adjustments within the module and it is advised that it is not
unnecessarily disassembled. Although the printed circuit boards are plugged
together, the connectors are a manufacturing aid and not intended for frequent
dismantling; in fact considerable effort may be required to separate them. Touching
the printed circuit board should be avoided, since complementary metal oxide
semiconductors (CMOS) are used, which can be damaged by static electricity
discharged from the body.
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 front plate, 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.
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