Influence of Temperature on Aging
Ambient Temperature Outside the Switchboard
The ambient temperature around the switchboard affects the device temperature, which is itself affected by the percent load.
Major variations in temperature (greater than 30 °C (86 °F)) cause both mechanical stresses (thermal expansion) and condensation, both of which can accelerate aging.
|
Influence |
Appearance |
Consequences |
|---|---|---|
|
Aging of plastic insulation. Deterioration of the mechanical characteristics of plastic parts (insulation, case) for which deterioration speed is increased with temperature rise. |
Change in color |
Breaking of parts leading to potential failure of functions |
|
|
|
|
Deterioration of insulating varnishes on coils. |
Burning smell |
Potential failure of coils (current transformers, MN, MX, or XF voltage releases, MCH gear motor, RES electrical remote reset) |
|
Hardening of glues. |
Visual |
Loss of labels |
|
Deterioration of electronic components. |
Modified display of LCDs |
|
|
Deterioration of opto-electronic devices and SCRs. |
Not identifiable |
Possible transmission of erroneous orders |
|
Interruption of battery backup power. |
Not identifiable |
Trip-cause indication not displayed |
Recommendations
The maintenance and installation recommendations according to the annual average ambient temperature Ta are defined in the following table:
|
Annual average ambient temperature Ta |
Description |
Maintenance recommendations |
Installation recommendations |
|---|---|---|---|
|
< 25 °C (77 °F) |
Optimum operating conditions |
Implement the Intermediate program. |
No particular recommendation |
|
25 to 35 °C (77 to 95 °F) |
A 10 °C (50 °F) increase in the ambient temperature is equivalent to a 5 % increase in the percent load. |
Carry out more frequent periodic checks. |
No particular recommendation |
|
35 to 45 °C (95 to 113 °F) |
A 20 °C (68 °F) increase in the ambient temperature is equivalent to a 10 % increase in the percent load. |
Carry out more frequent periodic checks. |
Install forced-air ventilation in the switchboard, or air conditioning for the electrical room. |
Example: Influence of the ambient temperature on the service life for a 1,000 A device, with an 80 % load.
|
Annual average ambient temperature Ta |
Typical service life of the device (electronic components excluded) |
|---|---|
|
25 °C (77 °F) |
30 years |
|
35 °C (95 °F) |
27 years |
|
45 °C (113 °F) |
25 years |