The wide-temperature selection determines whether the equipment can work, while the derating design determines how long it can work. This article gives a general accounting idea from the perspective of reliability life, which is applicable to communication equipment in cabinets, computer rooms, and outdoor nodes.

The lifespan depends on the continuous high temperature rather than the short-term exceeding of the limit.

The upper limit of operating temperature in the specification refers to the boundary that can still work normally for a short period of time; the device life is usually given in terms of the number of continuous operating hours at a certain reference temperature. A commonly used empirical relationship in the industry is that for every 10°C increase in temperature, the expected life of components such as electrolytic capacitors is approximately reduced by half. Therefore, when selecting a model, you should pay more attention to how many hours in a year the temperature is above 45 ℃, rather than the highest temperature measured at one time. The temperature reported by the module DDM is suitable for such cumulative statistics, which is more convincing than a single inspection.

Three types of components that age first

  • Power supply part: After long-term high temperature of the input filter capacitor and DC-DC device, the capacity decreases and the ripple increases, which manifests as occasional restarts;
  • Optoelectronic devices: The laser threshold current increases with the junction temperature, and the luminous power decreases under the same drive, and the link power margin is slowly eaten up;
  • Structural parts: Sealing rings and plastic parts harden and crack under high temperature and ultraviolet light. Then moisture and dust enter, and the problem turns into an environmental failure.

Derating can be done at the selection stage

There are four common practices: leaving a margin of one gear compared to the actual measured extreme value; the equipment load does not stay close to the nominal upper limit for a long time, and rack-mounted equipment needs to add the heat of the power module into the calculation; structurally ensure that the air inlet and outlet directions are not blocked by jumpers and fiber coils, leaving a self-cooling air channel between guide rail equipment; in monitoring, set the temperature alarm at 5°C to 8°C before the upper limit of the specification, so that operation and maintenance can intervene before the failure rate increases. Workshop and outdoor cabinet scenes can be combinedIndustrial automation and machine vision network solutionspower supply and temperature constraints, putSFP 100M single mode dual fiber 20KM optical moduleCheck the continuous operating temperature range of these commonly used models one by one.

The core of derating design is to turn the temperature into statistical data, rather than remembering an extreme value. When you already have a batch of equipment in service, EB-LINK technical support can help organize temperature specifications and margin references by model. Tel: 0755-83179002.