What's the difference between a 12v usb socket tested to the EN50155 standard for railway applications?

06/05/2022
If you are looking for such products as car chargers, 12v usb sockets, cigarette lighters, etc., it means that you already have an understanding of most of these products on the market. Have you ever encountered such a situation?
  • In order to save costs, poor materials are used, such as omitting fuses, using iron shells for USB sockets, and using poor-quality components for PCBA. These consequences are that when the car charger is used for a long time, the components fail, the car charger cannot be protected, and the battery fuse of the car may be burned out. USB is easy to rust, difficult to plug and unplug, and the service life is greatly reduced.
  • The craftsmanship is very poor. For example, the positive and negative terminals are not fixed and reliable, and they are not soldered to the PCB. They only rely on an internal device to achieve conduction; the USB does not solder the fixed pins. These will lead to some devices often have poor contact, and then sometimes good and bad and particularly not resistant to vibration.

Of course not only these, there may be more bad situations. In this case, it is actually recommended that you choose a 12v usb socket that has been tested by the EN50155 railway application standard.

First of all, what is EN50155 certification? What are the main aspects?

The railway has a history of more than 200 years. With the continuous advancement of technology, the speed of trains has greatly increased. Improving and ensuring passenger safety is an important topic in railway applications. But how do you increase driving speed and balance passenger safety with operational efficiency? It is one of the topics that rail transit operators attach great importance to in recent years.

EN50155 type test is to do environmental adaptability test, electromagnetic compatibility test, electrical safety test and other testing items of electronic equipment of railway vehicles. EN50155:2017 can be applied to all control, regulation, protection, diagnosis and other electronic equipment used on rail vehicles. When the car charger passes such an authoritative test, it just means that its product quality is guaranteed, and the above-mentioned problems will naturally not occur. So what are the main aspects?

All electronic equipment on rail vehicles must be able to adapt to environmental differences such as different altitudes, temperatures, humidity, shocks, vibrations, surges, electrical performance, etc., in order to meet the needs of railway traffic safety applications. Only a high level of stability can be maintained to ensure a safe journey.

 
  1. Shock and Vibration: The test methods used in EN50155 and their limits are in accordance with EN 61373 - Railway Applications - Rolling Stock Equipment - Shock and Vibration Tests. This standard can ensure that the car charger can withstand shock and shock, and guarantee the service life in a specific environment. To meet the requirements, the 12v usb charger should be designed and installed with a special shock mount.
  2. Temperature tolerance test: It should meet the requirements of storage under low temperature -40℃ and high temperature +85℃.
  3. Alternating humidity and heat: The relative humidity requirements specified in the EN50155 standard are: the car charger should be able to withstand an average annual relative humidity of 75% and a relative humidity of 95% for 30 consecutive days.
  4. Electrical safety performance: In order to make the 12v usb socket avoid serious damage and work normally for a long time, EN50155 also stipulates some standards for this, such as: input voltage range, input voltage ripple and input current peak value. Each category presents clear requirements.
  5. Electromagnetic Compatibility (EMC): Another main content of the EN50155 standard. We should protect the car charger from electromagnetic or radiated interference according to the EN 50121-3-2 standard, which also stipulates that the car charger should not emit more than a certain level of Radio Frequency Interference (RFI).
12v usb socket


After this series of tests, the car charger and 12v usb socket that have passed the test and obtained the qualification certification are recommended.