How to Maintain the Main Contacts
Functions
-
Fixed contact
-
Movable contact
The main contacts of the device:
-
Are mounted in the arc chamber
-
Are composed of the fixed and the movable contacts
The movable contacts make (close) or break (open) the electrical circuit under normal conditions (at rated current In) or fault conditions (overload and short-circuit).
Degradation Factors
The factors which can cause degradation of the main contacts are the following:
-
Frequent switching operations at rated current
-
Stresses due to high short-circuit currents
Potential Hazards
Performing regular maintenance on the main contacts can help to avoid the potential hazards and consequences listed in the following table.
|
Hazard |
Consequence |
|
|---|---|---|
|
Personal injury |
Equipment damage |
|
|
Fire |
Death or serious injury |
– |
|
Thermal dissipation due to high-resistance contact |
– |
Degradation of the breaking unit |
Preventive Action
The following table lists the preventive maintenance procedures to be performed to maintain the main contacts of the device.
|
Maintenance program |
Preventive action |
Procedure |
|---|---|---|
|
Intermediate end-user preventive maintenance |
Check the condition of the breaking unit. |
Breaking unit NIII_Z_1 Breaking unit NIII_2_1 Breaking unit NIII_ZA_1 |
|
Manufacturer preventive maintenance |
Measure the contact resistance for each pole. |
Contact your Schneider Electric Services representative. |
For more information, refer to Preventive Maintenance Programs.