Today, let’s explore the transmission performance of network cables in high and low temperature environments. We set the test ambient temperatures at -20℃ and 60℃ to conduct high and low temperature tests on the network cables, aiming to study how high and low temperatures affect the transmission performance of network cables.

The network cables were placed in a constant temperature and humidity test chamber to simulate the impact of high and low temperature environments on their transmission performance, and tests were carried out at -20℃ and 60℃.

First, at the conventional temperature of 20℃, Fluke permanent link tests are conducted on Category 5e engineering cables and standard network cables.

                                                                           Fluke Test Charts of Engineering Cables and Standard Cables at 20℃

It can be seen that both of them can pass the Fluke test and are cables that meet the transmission performance requirements.

Next, we test the transmission performance of the two bundles of cables in a low-temperature environment of -20℃.

In this environment, we use professional Fluke cable testing equipment to test the cables, so as to simulate the engineering acceptance of the cables under the low temperature of -20℃. After on-site testing, it can be seen from the test result report below that both types of cables can pass the Fluke permanent link test.

Of course, from the above test results, we can see that in addition to passing the test, the two types of cables also differ in their transmission performance test parameters. Next, we will conduct a quantitative analysis of these parameters one by one.

As can be seen from the above test results, for both engineering cables and standard network cables, the worst margin of insertion loss has increased by more than 2dB.

This is because the resistivity decreases as the temperature drops, and the reduction in DC loop resistance also leads to a decrease in insertion loss.

The worst margin of return loss has also changed by approximately 1dB. This is because when the temperature decreases, the temperature at each point of the cable does not drop to the same extent; therefore, the degree of cold shrinkage of the material at each point varies, which intensifies the imbalance of the cable's characteristic impedance and thus causes changes in return loss.

The worst margin values of the Equivalent Far-End Crosstalk Ratio (EFEXT) and Composite Equivalent Far-End Crosstalk Ratio (CEFEXT) have both increased by 1dB. This is related to the decrease in insertion loss: a smaller insertion loss results in greater signal integrity. Moreover, since the twisted structure of the cables does not undergo isomerization in the low-temperature environment, the noise intensity remains basically unchanged. Hence, both EFEXT and CEFEXT have increased.

However, the Attenuation-to-Crosstalk Ratio (ACR) remains basically unchanged. This is because ACR is the ratio of the signal to near-end crosstalk (NEXT), and as we know from the test report, the worst margin value of NEXT remains basically unchanged, while the change in insertion loss has little impact on it. Therefore, the worst margin of ACR remains almost unchanged.

After completing the low-temperature test at -20℃, we then proceed to test the transmission performance of the two bundles of cables in a high-temperature environment of 60℃.

In this environment, we use professional Fluke cable testing equipment to test the cables, so as to simulate the engineering acceptance of the cables under the high temperature of 60℃. After on-site testing, it can be seen from the test result report below that neither of these two types of cables has passed the Fluke permanent link test.

Of course, from the above test results, we can see that in addition to failing the test, the two types of cables also differ in their transmission performance test parameters. Next, we will conduct a quantitative analysis of these parameters one by one.

As can be seen from the above test results, for both engineering cables and standard network cables, the worst margin of insertion loss has decreased by approximately 2.8dB.

This is because the resistivity increases as the temperature rises, and the increase in DC loop resistance also leads to an increase in insertion loss, thus reducing the worst margin value.

The worst margin of return loss has also decreased by 1dB. The worst margin values of the Equivalent Far-End Crosstalk Ratio (EFEXT) and Composite Equivalent Far-End Crosstalk Ratio (CEFEXT) have both increased by 1dB. This is related to the increase in insertion loss: a larger insertion loss causes both the signal and noise to be attenuated. However, the noise itself has a low level, and after being attenuated by the insertion loss, the change in its level is greater than that of the signal. Therefore, both EFEXT and CEFEXT have increased.

However, the worst margin of the Attenuation-to-Crosstalk Ratio (ACR) remains basically unchanged. This is because ACR is the ratio of the signal to near-end crosstalk (NEXT), and as we know from the test report, the worst margin value of NEXT remains basically unchanged, while the change in insertion loss has little impact on it. Hence, the worst margin of ACR remains almost unchanged.

From the above test results, we can conclude that: Under a low-temperature environment of -20℃, the transmission performance of regular network cables is better than that at 20℃. However, when using network cables, we should not only focus on the transmission performance of the cables but also pay attention to the physical properties of the cable materials, such as the service life of PE/PVC. Low-temperature environments can impair the service life of these materials.