what is a ul listed adapter

Reliability definition of air purifier power adaptor
The so-called reliability of the ac dc adapter is the ability to complete the specified function (ie normal operation) under the specified conditions and within the specified time. If the specified conditions or the specified time are exceeded, the power adapter may not work reliably or even shorten its life.
Prescribed conditions-the environmental conditions, load size, and working methods under which the circuit works.
Specified time-the working time of the circuit to complete the specified function, that is, the time of normal work.
The specified function-the performance technical index of the circuit.
Through the use of various environmental test equipment to simulate the high temperature, low temperature, high temperature and high humidity, and temperature changes in the climatic environment, accelerate the reaction of the power adapter in the use environment to verify whether it meets the expectations in R&D, design, and manufacturing The quality target is to evaluate the overall power adapter to determine the reliability life of the power adapter.
Life/failure rate curve (bath tub curve) life curve(bath tub curve)
The life/failure rate curve refers to the change of reliability of the small power adapter during the entire life cycle from input to scrap. Practice has proved that most failure rates are a function of time. A typical failure curve is called a bathtub curve. The shape of the curve is high at both ends and low in the middle. It has obvious stages and can be divided into three stages: the juvenile failure period, Stable failure period, elderly failure period.

Infant mortality:
Due to some defects caused by the production process, materials used, or design, etc., the samples will cause a certain percentage of failures within a short period of use.

Stable failure period/random failure period:
During the stable working period of the device, most of the period, the performance gradually degrades with the self-generated aging cycle, and the failure rate distribution can be modeled by different material processes. The general obituary is a stable, or slowly rising curve.

Elderly failure period (wear out):
The device reaches the end of its service life, and due to the aging of the inherent material, a large proportion of it begins to fail.

Reliability requirements and accelerated aging of power adapter
The reliability of the universal power adapter needs to meet: under 24h operation, 2 restarts per day, average 80% data load, less than 200 plugs and unplugs, 60C 60%RH environment, standard voltage, current, standard bit rate, 10 years of cumulative failure The rate is less than 20%.
The optical communication industry is a branch of the electronics industry, and its reliability must also meet the above conditions. In the verification of the reliability of the actual power adapter, we usually use the user conditions that exceed the limit, that is, the accelerated condition or the stress condition to perform the experiment, that is, through accelerated aging, the equivalent shortened life span is used to reduce the experimental time, so as to reduce the experimental time as soon as possible The adapter was introduced to the market. There are a variety of accelerated aging models that convert the actual life requirements into the stress conditions and experimental duration in the model, including:
Thermal model thermal effective: Arrheniusmodel, JMAmodel, is the theoretical basis of HTOL/HTS.
Thermo-mechanical model Thermo-mechanical: Norris Landzberg model, which is the theoretical basis of TC/TS.
Thermo-moisture model Thermo-moisture: Peck’s, Shirley, Reich-hakim, Lawson, is the theoretical basis of DH.
Through reliability experiments, the overall power adapter is evaluated to verify whether the power adapter has reached the expected quality goals in R&D, design, and manufacturing. Treating the power adapters that fail in the aging experiment with caution and focusing on the analysis of the reasons for the failure will greatly help improve the quality of the power adapter.