Pressure test of the switching power supply adapter
Withstand voltage test of the electrical strength of the switching power supply adapter (electric withstand test) is often referred to as the pressure test, high voltage test between the live parts and case, try switching power supply primary and secondary circuit is many times greater than the rated The operating voltage of the high pressure, to verify that the live parts of the the measured switching power supply adapter without grounding or insulation breakdown. Test, the measured part is exposed to the non-normal voltage stress test. If the switching power supply due to the manufacturing process, any part of the elements or materials could cause insulation failure will occur the phenomenon of breakdown voltage; or smaller clearances due to some reason, the problem does not occur under normal operating voltage, but after a certain time , may be due to the accumulation of dust and moisture is too small gap, caused by the gap breakdown danger of electrical shock, pressure test can pre-discovered this hidden danger of the switching power supply adapter.
The switching power supply of the internal insulator several times in the working voltage conditions without breakdown, of course, is safe under normal operating conditions. At the same time, pressure test can test conductor gap is too small and workmanship, which is unmatched by any other tests.
Withstand voltage test is divided into frequency withstand voltage test (generally used in the production site), AC voltage withstand test (hot and cold), DC voltage test and pulse test (general electrical products do not do), switching power supply adapter resistance The pressure test is usually used AC voltage withstand test more.
Voltage test applied voltage value and the applied time. IEC335-1 (GB4706.1): AC 250V, insulation withstand one minute, frequency of 50Hz/60Hz sine wave voltage; applied voltage value and location can be found GB4706.1-1998. Hope to provide normal use SELV circuit insulation 500V, other basic insulation 1000V, additional insulation 2750V, reinforced insulation 3750V.
The test voltage in the start of the test is not more than half of the predetermined voltage, and then gradually add the predetermined value. Test breakdown shall occur, or not passed.
If you are using a DC test, the test voltage amplitude peak corresponding AC voltage UL60950 requirements similar. Reinforced insulation requirements 3750V AC test, then switch to the DC test voltage shall be 5303V.
For Class 1 equipment: minimum test voltage 2500V is applied between the input and the safety ground, minimum leakage current 30uA; minimum test voltage 5000V is applied between the input and output, minimum leakage current of 60 uA, test time is 1 min. Between input and output leakage 9 megohm resistor, set the minimum leakage current of 300 uA.
Applied for between 2 devices: input and DC output minimum test voltage 5000V minimum leakage current of 60 uA, test time is also 1min. Between input and output leakage resistance 9 megohms, set the minimum leakage current of 600 uA.
The above domestic product testing leakage current is higher than the specified value, but shall not exceed 10mA.