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18
INM MTL SUM5 Rev 1
5.5 Surge-protection module installation
In order to protect against induced voltage or current spikes carried on the field wiring,
surge protection can be provided by a plug-in module (Part No. MTL4-SD or MTL4-
SDR) that is installed on the top edge of the module base. (Note that there is no external
physical difference between the two modules – check the module marking.).
Figure 5.7
- Surge-protection module fitting
Unclip and raise the tag strip holder to obtain access to the connector on the top of the
module base. Check both connector pin interfaces to ensure the correct orientation then
press the module pins into the base and push it until fully seated. The tag strip can then
be folded down again until it clicks into place on the module. Removal of the module is
simply the reverse of this procedure.
To enable this module to protect the equipment, a low impedance, surge ground
connection MUST be installed from the carrier terminal (see Figure 4.4) to the plant
ground. Use a wire gauge that offers at least 4mm
2
cross-sectional area for this
connection. Check that each carrier that uses, or will use, surge protection is fitted with
this connecting wire.
5.6 Ground module installation
The Ground module (Part No. MTL4-GND) is a plug-in module that can be installed on
the top edge of the module base to provide a provisional ground connection for the field
wiring terminals of that channel. This is a useful safety measure for field wiring that is
installed, but not in current use.
Figure 5.8
- Ground module fitting
Unclip and raise the tag strip holder to obtain access to the connector on the top of the
module base. Check both connector pin interfaces to ensure the correct orientation then
press the module pins into the base and push it until fully seated. The tag strip can then
be folded down again until it clicks into place on the module. Removal of the module is
simply the reverse of this procedure.