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7
FAULT FINDING AND ROUTINE MAINTENANCE
7 .1
Maintenance precautions
Most Codes of Practice for intrinsic safety permit live maintenance on intrinsically safe devices
and systems, provided precautions are taken to preserve the integrity of the device or system.
During live maintenance of MTL5500 modules, the hazardous-area connectors that plug into
the tops of the modules are likely to be removed. Avoid leaving a hazardous-area connector
in a position where it may inadvertently contact non-IS circuits that are nearby. Prevent this by
providing some form of temporary mechanical method of securing the connector so that it cannot
come into contact with the non-IS circuits:
a) By plugging the connector into an MTL5599 dummy isolator
b) By using a tiewrap to constrain the connector in a safe position.
7 .2
Fault finding
When fault finding, carry out the following steps as far as is necessary:–
7 .2 .1
Check that all modules with power (PWR) LEDs are ON.
With the MTL5575 & MTL5576 models, a flashing LED indicates alarm or fault conditions, refer
to section 8. Note: The LED may also flash during intermediate stages of configuration.
7 .2 .2
Exchange potentially faulty modules for working units as follows:–
a) Unplug the hazardous-area connectors, then the safe area connectors.
b) Unplug any power connectors and remove from DIN rail.
c) Reverse this procedure to fit a replacement module.
7 .2 .3
Potentially faulty modules should be tested in workshop conditions, using an appropriate test
procedure for the particular module as described in Section 8.
7 .3
Routine maintenance
Check the general condition of the installation occasionally to make sure that no deterioration
has occurred. Carry out the following at least once every two years and more frequently for
particularly harsh environments:–
a) Check that modules are of the types specified in the relevant documentation.
b) Check that modules and hazardous-area connectors are correctly and legibly tagged, that
the connectors are plugged into the matching modules and that the tag details given
comply with the relevant documentation.
c) Check that hazardous- and safe-area connectors are securely plugged into their matching
sockets.
d) Check that all connections to the connectors are properly made.
e) Check that cables to connectors are of the specified type and rating, are correctly routed
and segregated (particularly in Eaton enclosures), and are not frayed or otherwise damaged.
f)
Check that cable screens are properly earthed.
Note: It is strongly recommended that only the tests (described in Section 8) and routine
maintenance (described here) should be undertaken by users. If a module is faulty, DO NOT
attempt to make repairs or modifications as these may affect the intrinsic safety of the module.
All faulty units should be returned to the Eaton's MTL product line or representative from which
they were purchased, for repair or replacement.
INM 5500 Rev 10
On removal, take care that a hazardous-area connector is not laid in a
position in which it may inadvertently come into contact with safe-area
circuit components .
WARNING
59
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