Grounding of Industrial Computer & Grounding Test
This file aims at introducing the essential points related to the grounding of industrial computers, telling the corresponding performance of grounding test to ensure the safe and reliable working environment for the board.
This file is applicable to those who use Synway products at the first time, and those who use Synway products to carry out projects, as well as those who come across troubles in the use of Synway products.
2. Way to Ensure Good Grounding of Industrial Computers
2.1. Why to Ground
A chassis installed with voice boards must be grounded for safety reasons, according to standard industry requirements. No or improper grounding may cause instability in operation and noises in call as well as decrease in lightning resistance. A simple way is earthing with the third pin on the plug. As long as the industrial computer is properly grounded, the grounding wire can conduct idle current or noises to the ground so as to greatly improve the board stability.
2.2. How to Ground
First of all, make sure the power cord of the industrial computer has a 3-phase plug and the corresponding third jack on the socket must be well grounded. If the third pin of the plug cannot be grounded, choose a stubby conductor (such as the water pipe or the ground wire of the building) to connect the PC chassis with the ground. To avoid a poor grounding, we suggest that you fix the conductor on the chassis with screws. Note that the resistance of the conductor itself should be less than 1Ω. Besides, the telephone wire is not recommended to work as the conductor.
2.3. How to Test
For instructions on how to install various Synway boards, refer to corresponding hardware manuals which can be downloaded from www.synway.net. After installing a board according to the requirements proposed in the corresponding manual, you can use such instrument as multimeter to test if the industrial computer has been well grounded. See below for details.
Use the multimeter for resistance measurements. Connect one pointed probe to the computer chassis and the other to the ground wire or the water pipe of the building. Thus you can test the grounding resistance between the ground and the chassis. In case of a good grounding, the result will not go larger than 5Ω; or the machine is regarded in a bad grounding. Note: As the shell of the machine is usually covered by insulated spray paint, if you choose an improper place for testing, the result may probably turn to be larger than the actual value. It is suggested that you select two testing places (e.g. the screws for fixing chassis) and make certain the resistance between them is less than 1Ω before you take one of them as a place for grounding test.
If the industrial computer is found not yet grounded during the test, please ground it following the steps described in the previous section ‘2.2 How to Ground’.