What is Withstand Voltage? How to measure?
That is, the Hi-Pot Test or the Electric Strength Test. Before the test, the Input terminals should be short-circuited to one point (I/P), and the Output terminals should be short-circuited to one point (O/P).
FG can only be tested after a single point. According to the following test circuit, the withstand voltage value between the specified terminals (such as I/P-O/P, I/P-FG, O/P-FG) (if the test voltage is AC, the leakage current is generally 25mA). benchmark), time 1 minute.
(1) The withstand voltage test is to ensure that the primary and secondary insulation of the power supply is good and to avoid the danger of electric shock. The test voltage must be gradually increased, from zero to the default voltage (rise time of at least 1 second), and stay at this point for 60 seconds. (During production test, the electric strength test time can be shortened to 1 second). An uncontrolled rapid increase in current due to application of the test voltage indicates that insulation penetration has occurred. A corona discharge or a single momentary flash is not considered to have penetrated the insulation.
(2) When using AC voltage test, Y capacitor is the main cause of leakage current. 4.7nF is enough to cause a leakage current of up to about 5mA. According to the requirements of UL-554, the Y-CAP needs to be removed, but this requirement is impractical for production. Increase, generally 25mA (current safety regulations do not define the current limit value).
(3) According to the requirements of IEC60950, DC test (AC 3KV=DC 4242V) can be used if the insulator to be tested has a cross-Y capacitor. The purpose is to solve the influence of AC on the leakage current of the Y capacitor.
