Disadvantages of Direct Current (DC) Testing
(1) Unless there is no capacitance on the measured object, the test voltage must start from “zero” and rise slowly to avoid excessive charging current. The added voltage is also lower. When the charging current is too large, it will definitely cause misjudgment by the tester and make the test result incorrect.
(2) Since the DC withstand voltage test will charge the object under test, after the test, the object under test must be discharged before proceeding to the next step.
(3) Unlike the AC test, the DC withstand voltage test can only be tested with a single polarity. If the product is to be used under AC voltage, this disadvantage must be considered. This is also the reason why most safety regulators recommend using the AC withstand voltage test.
(4) During the AC withstand voltage test, the peak value of the voltage is 1.4 times the value displayed by the electric meter, which cannot be displayed by the general electric meter, and also cannot be achieved by the DC withstand voltage test. Therefore, most safety regulations require that if a DC withstand voltage test is used, the test voltage must be increased to an equal value.
After the DC withstand voltage test is completed, if the object under test is not discharged, it is easy to cause electric shock to the operator; all our DC withstand voltage testers have a fast discharge function of 0.2s. After the DC withstand voltage test is completed, the tester It can automatically discharge the electricity on the tested body within 0.2s to protect the safety of the operator.
Introduction to the advantages and disadvantages of AC withstand voltage test
During the withstand voltage test, the voltage applied by the withstand voltage tester to the tested body is determined as follows: multiply the working voltage of the tested body by 2 and add 1000V. For example, the working voltage of a tested object is 220V, when the withstand voltage test is performed, the voltage of the withstand voltage tester is 220V+1000V=1440V, generally 1500V.
The withstand voltage test is divided into an AC withstand voltage test and a DC withstand voltage test; the advantages and disadvantages of the AC withstand voltage test are as follows:
The advantages of AC withstand voltage test:
(1) Generally speaking, the AC test is easier to be accepted by the safety unit than the DC test. The main reason is that most of the products use alternating current, and the alternating current test can test the positive and negative polarity of the product at the same time, which is completely consistent with the environment in which the product is used and is in line with the actual use situation.
(2) Since the stray capacitors cannot be fully charged during the AC test, but there will be no instantaneous inrush current, so there is no need to let the test voltage rise slowly, and the full voltage can be added at the beginning of the test, unless the product is sensitive to the inrush voltage very sensitive.
(3) Since the AC test cannot fill those stray capacitances, there is no need to discharge the test object after the test, which is another advantage.
Disadvantages of AC withstand voltage test:
(1) The main disadvantage is that if the stray capacitance of the measured object is large or the measured object is a capacitive load, the generated current will be much larger than the actual leakage current, so the actual leakage current cannot be known. current.
(2) Another disadvantage is that since the current required by the stray capacitance of the tested object must be supplied, the current output by the machine will be much larger than the current when using DC testing. This increases the risk to the operator.
Is there a difference between arc detection and test current?
1. About the use of arc detection function (ARC).
a. Arc is a physical phenomenon, specifically a high-frequency pulsed voltage.
b. Production conditions: environmental impact, process impact, material impact.
c. Arc is more and more concerned by everyone, and it is also one of the important conditions for measuring product quality.
d. The RK99 series program-controlled withstand voltage tester produced by our company has the function of arc detection. It samples the high-frequency pulse signal above 10KHz through a high-pass filter with a frequency response above 10KHz, and then compares it with the instrument benchmark to determine whether it is qualified. The current form can be set, and the level form can also be set.
e. How to choose the sensitivity level should be set by the user according to the product characteristics and requirements.
Post time: Oct-19-2022
