Areva MiCOM P921, Technical Manual

Page: 313 / 376

Technical Guide P92x/EN IN/E11
Installation
MiCOM P921-P922-P923 Page 3/10
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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 external damage has been sustained in transit. If damage has been
sustained, a claim should be made to the transport contractor and A REVA should
be promptly notified.
Relays that are supplied unmounted and not intended for immediate installation
should be returned to their protective polythene bags and delivery carton. Section 3
of this chapter gives more information about the storage of relays.
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, although not always
immediately apparent, will reduce the reliability of the circuit. This is particularly
important to consider where the circuits use complementary metal oxide
semiconductors (CMOS), as is the case with these relays.
The relay’s electronic circuits are protected from electrostatic discharge when housed
in the case. Do not expose them to risk by removing the front panel or printed circuit
boards unnecessarily.
Each printed circuit board incorporates the highest practicable protection for it’s
semiconductor 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 for which the relay has been designed and manufactured.
1. Before removing a printed circuit board, ensure that you are at the same
electrostatic potential as the equipment by touching the case.
2. Handle analogue input modules by the front panel, frame or edges of the
circuit boards. 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
the same electrostatic potential. Shaking hands achieves equipotential.
4. Place the module on an anti-static surface, or on a conducting surface which is
at the same 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.