P92x/EN IN/E11 Technical Guide
Installation
Page 4/10 MiCOM P921-P922-P923
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In the unlikely event that you are making measurements on the internal electronic
circuitry of a relay 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
500kW to 10MW. If a wrist strap is not available you should maintain regular contact
with the case to prevent a build-up of electrostatic potential. Instrumentation which
may be used for making measurements should also be earthed to the case whenever
possible.
More information on safe working procedures for all electronic equipment can be
found in BS EN 100015:Part 1:1992. 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 aforementioned British Standard
document.
3. STOCKAGE
If relays are not to be installed immediately upon receipt, they should be stored in a
place free from dust and moisture in their original cartons. Where de-humidifier bags
have been included in the packing they should be retained.
The action of the de-humidifier crystals will be impaired if the bag is exposed to
ambient conditions and may be restored by gently heating the bag for about an hour
prior to replacing it in the carton. To prevent battery drain during transportation and
storage a battery isolation strip is fitted during manufacture. With the lower access
cover open, presence of the battery isolation strip can be checked by a red tab
protruding from the positive side.
Care should be taken on subsequent unpacking that any dust which has collected on
the carton does not fall inside. In locations of high humidity the carton and packing
may become impregnated with moisture and the de-humidifier crystals will lose their
efficiency.
Prior to installation, relays should be stored at a temperature of between –25° to
+70°C.
4. UNPACKING
Care must be taken when unpacking and installing the relays so that none of the
parts are damaged and additional components are not accidentally left in the
packing or lost.
Relays must only be handled by skilled persons.
The site should be well lit to facilitate inspection, clean, dry and reasonably free from
dust and excessive vibration. This particularly applies to installations which are being
carried out at the same time as construction work.
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