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Basic Installation and Operation Guide
MAINTENANCE AFTER A FAULT CONDITION
The following covers procedures to return to service a medium voltage controller, which has been required to
interrupt a load side short-circuit or ground fault. These procedures are not intended to cover devices such as wiring
and motors, which may also require attention.
In an installation which has been properly coordinated and in service prior to a fault, the opening of the current-
limiting power fuses in the controller indicates a fault condition in excess of operating overload. This fault condition
must be corrected and necessary repairs made to the load circuit before re-energizing the controller.
The following inspection and repair procedures should be carried out by qualified personnel.
WARNING
Enclosure
Check the condition of the enclosure for any signs of bowing or deformation. Check the condition of the doors and
latches for damage.
If substantial damage has occurred to the enclosure, such as deformation, displacement of parts, or burning, this
indicates a problem within the controller that requires major reconditioning or complete replacement of the controller.
In this event, contact the nearest Toshiba representative.
Isolation Switch
The external operating handle must be capable of opening the switch. If the handle fails to open the switch or if
visual inspection after opening indicates deterioration beyond normal wear and tear such as overheating or pitting
of blades, insulation breakage, or charring, contact your Toshiba representative.
Fuse Mounting
Check the condition of the power fuse mounting hardware, clamps, and insulating bases. Any deterioration of these
components requires replacement of the damaged parts.
Terminals and Internal Conductors
Indication of arcing damage, overheating, or both, such as discoloration and melting of insulation, requires
replacement of the damaged parts.
Overload Relay
The overload relay must be checked to verify that it will still trip properly. Follow the test instructions provided with
the overload device for verifying trip characteristics.
Vacuum Contactor
Operate the vacuum contactor electrically from test power and observe that it opens and closes freely. If the vacuum
bottles show any sign of binding, they should be replaced. Contact your Toshiba representative. Check for any
sign of arcing damage to the insulated housing.
Return to Service
Before returning the controller to service, repeat the procedure outlined in the PRE-ENERGIZATION CHECK
section of this manual.
TOSHIBA
Hazardous Voltage. Turn off and lock out Primary and Control Circuit Power
before any inspection or testing.
JK 400 Series Fixed Controllers
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