# Accelerated lifetime / thermal ageing of power cables

• Casper Hansen
In summary, the conversation discusses the possibility of performing accelerated lifetime tests on power cables to estimate their expected life span. It also touches on the idea of using the Arrhenius equation to calculate the expected life time and the availability of IEC standards for this purpose. The conversation also mentions the possibility of the cable manufacturer performing similar tests for thermal degradation of the insulation material and the potential consequences of premature failure of a power cable.

#### Casper Hansen

Hi PF

Is it possible to perform accelerated lifetime test of thermal ageing on power cables?

Let's assume that the cable manufacturer guarantees a service life time of 20 years at max operation temperature 90 [degC]. Is it possible to estimate the expected life time of a cable if I choose to operate my cable above the 90 [degC] let's say 100 [degC]. Maybe the expected life time could be calculated using Arrhenius equation?

Are there any IEC standards that deal with this? That i can use to estimate the life time of a cable

I know that the cable manufacturer do accelerated lifetime voltage test on cables where they test breakdown at 4xU0 (4 times rated voltage) at 4 hours. Does they perform similar tests for thermal degradation of the insulation material?

I would contact the cable manufacturer. They are the ones with the expertise and know all of what goes into an age estimate.

Casper Hansen said:
Maybe the expected life time could be calculated using Arrhenius equation?
I think that's the way it is usually done. You need an appropriate value for the activation energy.

Casper Hansen
I found this standard IEC 60216 series anyone have been working with it?
.Scott said:
I would contact the cable manufacturer. They are the ones with the expertise and know all of what goes into an age estimate.
I have tried that they could not tell.

gmax137 said:
I think that's the way it is usually done. You need an appropriate value for the activation energy.
If i have two temperature points i can estimate the activation energy?

lets say:
operation temperature: 90 [degC] @ 20 years (631 138 519 s)
Short circuit temperature 250 [degC] @ 5 s

CWatters said:

https://ieeexplore.ieee.org/document/4111066/

But I haven't read it. Bit dated perhaps.
Thanks I'll look into that.

Casper Hansen said:
If i have two temperature points i can estimate the activation energy?

Technically, yes.

lets say:
operation temperature: 90 [degC] @ 20 years (631 138 519 s)
Short circuit temperature 250 [degC] @ 5 s

Nope, not from this data. One temperature refers to slow degradation, the other to fast thermal decomposition, these are different (chemically) processes, so they have different activation energies (actually thermal decomposition is a mixture of competing, parallel processes, which makes it even more complicated).

If you had data for - say - 50°C and 90°C, that would make sense.

Lord Jestocost and gmax137
What type of cable are you interested in? Medium voltage, high voltage or low voltage?

A number of labs around the world have performed accelerated aging on medium voltage cables (mostly 15 kV to 34.5 kV). The temperature and applied voltage are usually set higher than normal to permit meaningful results in approximately 3 years or so.

You might check NEETRAC, an independent testing facility that is part of Georgia Tech in Atlanta. CTL (Cable Technologies Lab) in New Jersey has done aging tests for different clients. Finally, General Cable has done quite a bit of testing in their lab in Texas.

IREC in Montreal has done some of this testing too, and CESI in Italy has done some.

Casper Hansen said:
.Scott said:
I would contact the cable manufacturer. They are the ones with the expertise and know all of what goes into an age estimate.
I have tried that they could not tell.​

Then my next question would be: What would the consequences be of premature failure of this power cable? More specifically, is it life-critical, mission-critical, or just a nuisance?​

An increase of the operating temperature by 8 to 10°C reduces the service life by half.

Which nicely fits the old rule of thumb "raising the temperature by 10°C makes the reaction twice faster". This is based on the observation activation energies of many reactions fall in the same range of tens of kJ.

ChemAir, Bystander and jim hardy
Casper Hansen said:
Hi PF

Is it possible to perform accelerated lifetime test of thermal ageing on power cables?

Let's assume that the cable manufacturer guarantees a service life time of 20 years at max operation temperature 90 [degC]. Is it possible to estimate the expected life time of a cable if I choose to operate my cable above the 90 [degC] let's say 100 [degC]. Maybe the expected life time could be calculated using Arrhenius equation?

Are there any IEC standards that deal with this? That i can use to estimate the life time of a cable

I know that the cable manufacturer do accelerated lifetime voltage test on cables where they test breakdown at 4xU0 (4 times rated voltage) at 4 hours. Does they perform similar tests for thermal degradation of the insulation material?

You can do accelerated lifetime studies on pretty much ANYTHING. NOTHING in this universe is actually static and unchanging - it's only the limitations of human perception that create the illusion of static qualities.

To know if a cable will have problems, contacting the manufacturer probably save a lot of time. Doing your own studies are absolutely possible but to get them right they will take time and it very much helps to know a lot about how the thing was manufactured to do that correctly.

## 1. What is accelerated lifetime/thermal ageing of power cables?

Accelerated lifetime/thermal ageing of power cables is a process in which power cables are subjected to artificially increased levels of heat and other environmental stressors in order to simulate the effects of long-term use. This process is used to predict the performance and lifespan of power cables in real-world conditions.

## 2. Why is accelerated lifetime/thermal ageing of power cables important?

Accelerated lifetime/thermal ageing of power cables is important because it allows us to test and evaluate the durability and reliability of power cables before they are installed in critical applications. This helps ensure that they will perform safely and efficiently over their intended lifespan.

## 3. What factors can accelerate the ageing of power cables?

The ageing of power cables can be accelerated by a variety of factors, including increased temperature, exposure to chemicals, mechanical stress, and electrical stress. These factors can cause degradation of the cable's insulation and other components, leading to reduced performance and potentially causing safety hazards.

## 4. How is accelerated lifetime/thermal ageing of power cables tested?

Accelerated lifetime/thermal ageing of power cables is typically tested in a controlled laboratory setting, where the cables are exposed to elevated temperatures and other stressors for an extended period of time. The performance and condition of the cables are then monitored and evaluated to determine their expected lifespan and any potential weaknesses or failures.

## 5. Are there regulations or standards for accelerated lifetime/thermal ageing of power cables?

Yes, there are international standards and regulations that govern the testing and evaluation of power cables, including their accelerated ageing. These standards, such as IEC 60287 and IEEE 400, provide guidelines for conducting these tests and interpreting the results to ensure the safety and reliability of power cables in various applications.