LEGRAND DMX3 Mode D'emploi page 97

DMX
3
How to restore device after tripping
How to restore device after tripping
Follow the below procedures in case of tripping:
• identify the reason of the release and identify if it
is caused by a protection event or by an external
circuit
• check protection unit history log (see protection
unit instruction sheet)
• verify position of MAN/AUT button . If in MAN
mode after tripping, RESET button is on released
position and it's now impossible to re-close the
breaker . In this situation, operator must clarify
and solve fault cause before turning back RESET
button to normal working position .
If in AUT mod after tripping, device is able to
close even after a protection trip, without any
action on-the-field by operator . If needed, with
the presence of a remote supervision system, the
breaker can be automatically closed by remote .
Fault identification
Fault is shown locally on protection unit and/or by
auxiliary contacts installed on device . In case of fault,
it's strongly recommended to inspect device .
Fault reasons
Never re-close (locally or by remote) the breaker
after tripping operation if not properly identified and
solved the cause of the fault .
The events can have different origin and they can be
classified into two main categories:
• Fault protection (see history log of protection unit)
• ST and/or UVR operations by remote
After checking fault reasons, before closing again
device, it's recommended to check device conditions
and, above all, to check dielectric and insulation
device situations (depending on the kind of tripping
event) .
These checks and verifications must be organised
and managed by qualified people, according to
what written in this instruction manual .
Device inspection in case of short-cir-
cuit
In case of short-circuit protection, check the following
conditions:
• arc chamber status and wear status
• main contacts status
• tightening of power connections and auxiliary
circuit connections
• in case of withdrawable version, draw-out the
breaker, verify the status of clamps and internal
side of the breaker .
Device closing
To close the breaker is possible locally or by remote
only after checking the status of the plant and the
compliance of the device with the safety standards .
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