Views: 0 Author: Site Editor Publish Time: 2018-03-28 Origin: Site
As a widely used varistor, overvoltage protected varistor is often used to protect thyristor rectifier. How should we choose a suitable over-voltage protection varistor? In general, the 3kA varistor model is usually used for surge absorption of electrical equipment, while the 5kA resistor model is mostly used for the protection of lightning strikes and overvoltage absorption of electronic equipment. Here we take lightning protection as an example.
Usually in the test, we choose the common synthetic wave (the voltage wave of 1.2 / 50 μ s when the generator output is open circuit; the current wave of 8 / 20 μ s when the short circuit output; the internal resistance of the generator is 2 Ω) to check the ability of the equipment to resist the lightning surge interference on-line. In the 4kV test, the current absorbed by the over-voltage protected varistor is up to 2 kA. For the 6kV test, the absorption current value is 3kA. However, in the actual selection, we should also appropriately increase the current capacity of the selected over-voltage protection varistor.
"Mwandishi wa ""Site Editor"" na ""Mwandishi wa tovuti"" ni ""Mwandishi wa tovuti"" na ""Mwandishi wa tovuti"" ni ""Mwandishi wa tovuti"" na ""Mwandishi wa tovuti"" ni ""Mwandishi wa tovuti"" na ""Mwandishi wa tovuti"" ni ""Mwandishi wa tovuti"" na ""Mwandishi wa tovuti"" ni ""Mwandishi wa tovuti.""" Jinsi gani tunapaswa kuchagua sahihi juu ya voltage ulinzi varistor? Kwa ujumla, 3kA varistor ni kawaida kutumika kwa ajili ya kuondoa mwinuko wa vifaa vya umeme, wakati 5kA upinzani ni hasa kutumika kwa ajili ya ulinzi wa umeme na overvoltage kuondoa vifaa vya umeme. Hapa sisi kuchukua ulinzi umeme kama mfano. Kwa kawaida, katika mtihani, sisi kuchagua wimbi la kawaida la synthetic (wimbi la voltage ya 1.250 m s wakati pato la jenereta ni mzunguko wa wazi, wimbi la sasa la 820 m s wakati pato la mzunguko mfupi, upinzani wa ndani wa jenereta ni 2 m) ili kuangalia uwezo wa vifaa vya kupinga kuingiliana kwa umeme. Katika mtihani wa 4kV, mkondo unaoingizwa na varistor iliyohifadhiwa kwa voltage ni hadi 2kV. Kwa ajili ya mtihani wa 6kV, thamani ya sasa ya kunyonya ni 3kA. Hata hivyo, katika uteuzi halisi, tunapaswa pia ipasavyo kuongeza uwezo wa sasa wa kuchaguliwa juu ya voltage ulinzi varistor.