Surge is caused by switching transients and lightning transients in the power system; and the purpose of the surge immunity test is to establish a ****similar benchmark for evaluating the performance of electrical and electronic equipment when subjected to surges (shocks). According to the standard IEC61000-4-5 surge impact immunity test general requirements, lightning surge generator simulates 1.2/50us voltage waveform, 8/20us current waveform and combined waveform (voltage waveform: 10/700us, current waveform: 5/320us), through the coupling network, the waveform is coupled to the circuit under test, and has reached the experimental purpose. The experimental levels are categorized into 1, 2, 3, 4 and X according to the degree of voltage severity, where X and is the open level, and the corresponding voltage intensity of each level is shown in Table I. Severe level of application depends on the environment (the possibility of suffering a surge environment) and installation conditions, lightning surge test is generally categorized in accordance with the following conditions:
1 level: better protected environment, such as factories or power station control room.
Level 2: a certain degree of protection of the environment, such as factories without strong interference.
Level 3: Ordinary electromagnetic nuisance environments, where no special installation requirements are specified for the equipment, such as cable networks for ordinary installations, industrial workplaces and power substations.
Level 4: Environments subject to severe harassment, such as civil overhead lines, unprotected high-voltage substations.
Class X: Special class, determined by the user and the manufacturer after consultation. Specific product selection of which level, generally set by the product standard.
Lightning surge test results:
Lightning surge test is a destructive test, depending on the degree of destruction of the object under test, divided into the following cases:
a) in the manufacturer, commissioned by the purchaser of the limit value specified by the performance of the normal
b) the function or performance of the temporary loss or degradation, but in the harassment ceased to recover on its own without the need for intervention of the operator
c) Temporary loss or degradation of function or performance that requires operator intervention to recover;
d) Unrecoverable loss of function or degradation of performance due to damage to the equipment's hardware or software, or loss of data.