Advantages and disadvantages of AC voltage withstand test and DC voltage withstand test

Advantages and disadvantages of AC voltage withstand test and DC voltage withstand test
Please confirm with the designated safety unit of the tested product what voltage the product should use. Some products can accept both DC and AC testing options, but there are still multiple products that only allow for one of DC or AC testing.
If safety regulations allow for simultaneous DC or AC testing, manufacturers can decide for themselves which testing is more appropriate for the product. To achieve this goal, it is necessary to understand the advantages and disadvantages of DC and AC testing.

1、 Characteristics and classification of alternating current withstand voltage (ACW) testing
Most of the tested objects for voltage endurance testing will contain some discrete electrical capacity. During communication testing, it may not be possible to fully charge these discrete capacitors, resulting in a continuous current flowing through them.

1. Advantages of AC Voltage Withstand (ACW) Testing
Generally speaking, AC testing is more easily accepted by safety regulatory agencies than DC testing. The main reason is that most products use alternating current. And communication testing can simultaneously test the positive and negative polarity of the product, which is completely consistent with the environment in which the product is used and in line with actual usage conditions.
Due to the inability to fully charge the discrete capacitors during communication testing, there will be no instantaneous surge current, so there is no need to slowly increase the test voltage. The full voltage can be applied from the beginning of the test, unless the product is sensitive to surge voltage.
Due to the inability of communication testing to fully charge those discrete capacitors, there is no need to discharge the test object after testing, which is another advantage.
2. Disadvantages of AC Voltage Withstand (ACW) Testing

2、 Characteristics of DC Withstand Voltage (DCW) Test
During the DC withstand voltage test, the discrete capacitors on the tested object will be fully charged, and the capacitive current caused by the DC withstand voltage test will drop to zero after the capacitive capacitors are fully charged.
1. Advantages of DC withstand voltage (DCW) testing
Once the discrete capacitors on the tested object are fully charged, only the actual leakage current of the tested object remains. DC withstand voltage testing can clearly display the actual leakage current of the tested object.
Another advantage is that the charging current of the tested object only needs to be supplied in a short period of time, and the current required for other times is very small, so the current capacity of the machine is much lower than that required for AC withstand voltage testing.
2. Disadvantages of DC Withstand Voltage (DCW) Testing
Unless there is no capacitance present on the tested object, the test voltage must start from “zero” and slowly rise to avoid excessive charging current. The larger the capacitance, the longer the required slow rise time and the lower the voltage that can be increased at once. When the charging current is too high, it will definitely cause misjudgment by the tester, resulting in incorrect test results.
Due to the fact that DC withstand voltage testing charges the tested object, it is necessary to discharge the tested object (such as a battery) before conducting the test. Unlike AC testing, DC withstand voltage testing can only perform single polarity testing. If the product is to be used under AC voltage, this disadvantage must be considered. This is also the reason why most safety regulatory agencies recommend using AC withstand voltage testing. During the AC withstand voltage test, the peak value of the voltage is 1.4 times the displayed value on the electricity meter, which is something that cannot be displayed on a typical electricity meter and cannot be achieved through DC withstand voltage testing. So most safety regulatory agencies require that if using DC withstand voltage testing, the test voltage must be increased to an equal value.