Areva MiCOM P921, Technical Manual

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Technical Guide P92x/EN IN/E11
Installation
MiCOM P921-P922-P923 Page 5/10
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5. RELAY MOUNTING
MiCOM relays are dispatched either individually or as part of a panel/rack assembly.
Individual relays are normally supplied with an outline diagram showing the
dimensions for panel cut-outs and hole centres. This information can also be found in
the product publication.
Secondary front covers can also be supplied as an option item to prevent
unauthorised changing of settings and alarm status. They can be ordered under the
reference GEN0055 (size 20TE).
The design of the relay is such that the fixing holes in the mounting flanges are only
accessible when the access top and bottom covers are open and hidden from sight
when the covers are closed.
If an MMLG test block is to be included, it is recommended that, when viewed from
the front, it is positioned on the right-hand side of the relay (or relays) with which it is
associated. This minimises the wiring between the relay and test block, and allows the
correct test block to be easily identified during commissioning and maintenance tests.
5.1 Rack Mounting
MiCOM relays may be rack mounted using single tier rack frames (our part number
FX0021 001), as illustrated in Figure 1. These frames have been designed to have
dimensions in accordance with IEC60297 and are supplied pre-assembled ready to
use. On a standard 483 mm rack system this enables combinations of widths of case
up to a total equivalent of size 80TE to be mounted side by side.
The two horizontal rails of the rack frame have holes drilled at approximately 26 mm
intervals and the relays are attached via their mounting flanges using No.4 recessed
head self-tapping screws.
Once the tier is complete, the frames are fastened into the racks using mounting
angles at each end of the tier.