How to Maintain the Case - NT/NW Maintenance Guide

The case of the device:

Insulates the main contacts
Helps to protect the user against arcing effects
Provides a support for:
- Mechanism
- Control unit
- Auxiliaries
- Power connection
Withstands the thermal and electrodynamic stresses generated during short-circuits

The factors which can cause degradation of the case are the following:

Performing regular maintenance on the case can help to avoid the potential hazards and consequences listed in the following table.

Hazard	Consequence
Hazard	Personal injury	Equipment damage
Arc flash	Death or serious injury	–
Insulation resistance of the case too low and impulse voltage	Electric shock	–
Disruptive discharge	–	Degradation of the breaking unit
High short-circuit current	–	Degradation of the breaking unit

The following table lists the preventive maintenance procedures to be performed to maintain the case of the device.

Maintenance program	Preventive action	Procedure
Basic end-user preventive maintenance	Check the general condition of the device.	Device NII_1_1
Manufacturer preventive maintenance	Measure the insulation resistance.	Contact your Schneider Electric field service representative.

For more information, refer to Preventive Maintenance Programs.