UL 1449 Surge Protective Device Standard Update: New Test Requirements for Wet Environment ApplicationsUnderstanding the UL 1449 Surge Protective Devices (SPDS) standard update, which adds new test requirements for products in humid environment applications, mainly using constant temperature and humidity testing. Learn what a surge protector is and what a humid environment is.
October 25, 2022.
Surge protective devices (SPDs) have always been regarded as the most important protection in electronic equipment, which can prevent the accumulation of power and power fluctuations, so that the protected equipment will not be damaged by sudden electrical shocks. A surge protector can be a complete device designed as a stand-alone design, or it can be designed as a component to be installed in the electrical equipment of the power system.
As mentioned above, surge protectors can be used differently, but they are always extremely critical when it comes to safety features. The UL 1449 standard is a standard requirement that practitioners are familiar with when applying for market access.
With the increasing complexity of electronic devices and their application in more and more industries, such as LED street lights, railways, 5G, photovoltaics and automotive electronics, the use and development of surge protectors is increasing rapidly, and industry standards also need to keep pace with the times and keep up-to-date.
Definition of a humid environment.
Both the National Fire Protection Association's (NFPA) NFPA 70 and the National Electrical Code (NEC) have clearly defined "damp location" as follows:
locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture.(Locations that are not affected by the weather and are not soaked with water or other liquids, but are subject to moderate humidity.) ）
Specifically, tents, open porches, and basements or refrigerated warehouses are what are defined by the regulations as "moderately wet" locations.
When a surge protector (e.g. varistor) is installed in an end product, it is most likely because the end product is installed or used in an environment with variable humidity, and it is important to consider whether the surge protector can meet the safety standards of the general environment in such a humid environment.
Requirements for product performance evaluation in humid environments.
Many standards explicitly require that a product must pass a series of reliability tests to verify performance over the life cycle of the product, e.g. by performing itHigh temperature and humidity, cold and hot shock, vibration and fallingand other test items. When it comes to simulating a humid environment, the constant temperature and humidity test will be used as the main evaluation, especially the combination of two sets of parameters, 85°C temperature and 85% humidity (commonly known as "double 85 test") and 40°C temperature and 93% humidity.
The constant temperature and humidity test aims to accelerate the life of the product through experimental methods, and it can well evaluate the anti-aging ability of the product, including whether the product has the characteristics of long life and low wear and tear in special environments.
We have conducted a questionnaire survey on the industry, and the results show that a considerable number of end product manufacturers are making temperature and humidity assessment requirements for surge protective devices and components used internally, but the UL 1449 standard at that time has not yet corresponded to the requirements, so manufacturers must obtain UL 1449 certificates and then conduct additional tests on their own; In the case of a third-party certification report, the aforementioned operational process becomes less viable. In addition, when applying for UL certification for the finished product, it will also encounter the situation that additional evaluation is required because the internal pressure sensitive component certification report does not include the test for wet environment applications.
We understand the needs of our customers and are determined to help them solve the pain points they encounter in practical operations, and UL has launched an update plan for the 1449 standard.
The corresponding test requirements added to the standard.
The UL 1449 standard has recently added testing requirements for products in wet environments (damp location) applicationsManufacturers may choose to add this new test to their test cases at the same time as applying for UL certification.
As mentioned above, the test for humid environment applications will mainly use constant temperature and humidity testing. The following is an overview of the test process for verifying that a varistor (MOV) gas discharge tube (GDT) is suitable for wet applications
The test sample will first undergo an aging test under 1000 hours of high temperature and high humidity conditions, and then the varistor voltage of the varistor or the breakdown voltage of the gas discharge tube will be compared to confirm whether the surge protection component can maintain its original protection performance in a long-term humid environment.
Table 1: The test methods required for MOV and GDT respectively in the standard:
Table 1) Once the test has been successfully obtained for UL certification, the SPD component will be updated in the UL Product IQ online certification catalog platform for the end product manufacturer to find the product model number that is suitable for wet environment applications (as shown in the figure).
1 and 2), and then save the overall certification process of the finished product.
Figure 1).
Figure 2).
Let's talk about the two sessions in 2024