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Multi-channel safety gauge test (advantages and di


Please first determine whether the product under test is allowed to use ac voltage or dc voltage by the corresponding safety gauge unit, which should be tested according to the requirements. Some products can be tested with either ac voltage or dc voltage, so the manufacturer can decide to use ac voltage test or dc voltage test according to the characteristics of the product, the user must understand the advantages and disadvantages of the two kinds of test voltage.


Characteristics of ac withstand voltage (ACW) test


Most products that are tested for voltage will have a stray capacitance, a continuous capacitive current flowing through the stray capacitance when tested with ac.


1, ac voltage withstand (ACW) test advantages


(1) generally speaking, ac test is easier to be accepted by safety regulation unit than dc test. This is because most of the products are using alternating current, and ac test can test the positive and negative polarity of the product at the same time, and the use of the environment of the product is completely consistent with the actual use condition.


(2) unless the product is particularly sensitive to impulse voltage, or the standard requires slow voltage boost, the full voltage may be applied directly at the beginning of the ac test.


(3) generally, there is no need to wait for discharge after ac test.


2. Disadvantages of communication test


(1) if the stray capacitance of the object to be measured is large or the object to be measured is a capacitive load, the current generated in the ac test will be much larger than the actual leakage current, so the actual leakage current of the object to be measured cannot be known.


(2) another disadvantage is that the test instrument needs to supply the current required by stray capacitance, so the current supplied by the instrument is larger than that of dc test. Sometimes very powerful instruments are needed to test properly.


Characteristics of dc voltage resistance (DCW) test


In the dc voltage test, the stray capacitance of the object to be measured will be fully charged, and the capacitive current will eventually drop to zero.


1. Advantages of dc voltage resistance (DCW) test


(1) once the stray capacitance of the object to be measured is fully charged, only the actual leakage current of the object to be measured remains. Therefore, the dc withstand voltage test can clearly show the actual leakage current of the object to be measured.


(2) the power of the instrument is much lower than that of the ac withstand voltage test instrument because the charging current of stray capacitor is only needed in a short time and the current required in other times is very small.


2. Disadvantages of dc voltage resistance (DCW) test


(1) unless there is no capacitance on the object to be measured, the test voltage must rise slowly from "zero" to avoid excessive charging current. The higher the capacitance is, the longer the slow rise time is required, and the lower the voltage can be increased at one time. Charging current is too large will cause the wrong judgment of the tester, so that the test results are not correct.


(2) since the dc withstand voltage test will be used to charge the test object, so after the test, we must first treat the test object discharge, to do the next step.


(3) unlike the ac withstand test, the dc withstand test can only do a single polarity test, which must be fully considered if the product is to be used at ac. This is why most safety regulators recommend the use of ac withstand voltage testing.


(4) in the ac withstand voltage test, the voltage crest value is 1.4 times of the voltage indication value, so most safety gauge units require that, if using the dc withstand voltage test, the test voltage must be increased to the same value.


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