When performing a DC withstand voltage test, what is the withstand voltage time?

AC withstand voltage and DC withstand voltage are both withstand voltage tests, which are methods to identify the dielectric strength of power equipment. Insulation preventive test, electrical equipment insulation preventive test is an important measure to ensure the safe operation of the equipment, through the test, grasp the equipment insulation status, timely find the hidden defects inside the insulation, and eliminate them through maintenance, serious ones must be replaced, so as to avoid insulation breakdown in the operation of the equipment, resulting in irreparable losses such as power failure or equipment damage. Insulation preventive tests can be divided into two main categories:

The first type is the non-destructive test or insulation characteristic test, which is a variety of characteristic parameters measured at a lower voltage or with other methods that will not damage the insulation, mainly including measuring the insulation resistance, leakage current, dielectric loss tangent, etc., so as to judge whether there are defects in the insulation. Experiments have shown that this method is effective, but it cannot be relied on alone to reliably judge the electrical strength of the insulation. The other type is the destructive test or withstand voltage test, the voltage applied by the test is higher than the working voltage of the equipment, and the insulation test is very strict, especially to expose those dangerous concentrated defects, and can ensure that the insulation has a certain electrical strength, mainly including DC withstand voltage, AC withstand voltage, etc.

The disadvantage of the withstand voltage test is that it will cause certain damage to the insulation. DC withstand voltage testDC withstand voltage test voltage is high, which has a special role in finding some local defects of insulation, and can be carried out at the same time as leakage current test. Compared with the AC withstand voltage test, the DC withstand voltage test has the advantages of light test equipment, small damage to insulation and easy to find local defects of the equipment.

Compared with the AC withstand voltage test, the main disadvantage of the DC withstand voltage test is that due to the different voltage distribution inside the insulation under AC and DC, the test of the insulation in the DC withstand voltage test is not as close to the reality as that of AC. AC withstand voltage test, AC withstand voltage test is very strict on the test of insulation, can effectively find more dangerous concentration defects. It is the most direct method to identify the dielectric strength of electrical equipment, which is of decisive significance for judging whether electrical equipment can be put into operation, and is also an important means to ensure the insulation level of equipment and avoid insulation accidents.

The AC withstand voltage test may sometimes make some weaknesses in the insulation more developed, so the test must be carried out on the test of insulation resistance, absorption ratio, leakage current and dielectric loss before the test, and the AC withstand voltage test can be carried out only if the test result is qualified. Otherwise, it should be dealt with in time, and the AC withstand voltage test should be carried out after the indicators are qualified, so as not to cause undue insulation damage. <>

When the DC withstand voltage test or the insulation resistance measurement of the main insulation of the cable is carried out, it should be carried out on each phase separately. When testing or measuring a phase, the other two-phase conductors, metal shields or metal sleeves are grounded together with the armor layer. The newly laid cable line has been put into operation for 3 12 months, and generally should be tested for 1 DC withstand voltage, and then tested according to the normal cycle.

The test results are abnormal, but according to the comprehensive judgment that the cable line that is allowed to continue to operate under the monitoring conditions, the test period should be shortened, if in not less than 6 months, after more than 3 consecutive tests, the test results will not deteriorate, then the normal cycle test can be carried out later. When the main insulation of a single-core cable with a sheath overvoltage protector at one end grounded at one end of the metal shield or metal sleeve and a sheath overvoltage protector at the other end for the DC withstand voltage test, the sheath overvoltage protector must be short-circuited to make the cable metal shield or metal sleeve at this end temporarily grounded. <>

During the DC withstand voltage test, the leakage current should be measured 1 min after the test voltage rises to the specified value and when the pressurization time reaches the specified value. The leakage current value and the unbalance coefficient (the ratio of the maximum value to the minimum value) are only used as a reference for judging the insulation condition, and are not used as a criterion for whether it can be put into operation. However, if it is found that the leakage current has changed significantly from the previous test value, or if the leakage current is unstable and rises sharply with the increase of the test voltage or the increase of the pressurization time, the cause should be investigated.

If it is the influence of factors such as leakage current on the surface of the terminal head or stray current to the ground, it should be eliminated; If it is suspected that the cable line is poorly insulated, the test voltage can be increased (it is advisable not to exceed the factory test DC voltage specified in the product standard) or the test time can be extended to determine whether the operation can be continued. <>

Hello, I am happy to serve you and give you the following answers: the duration of the AC withstand voltage test is generally 1 minute, but in actual operation, sometimes the voltage can not reach the standard voltage. The solution to this problem is to judge Morino the following points:

1.Check whether the power supply voltage is stable, if not, you can take measures to stabilize the power supply voltage; 2.Check if the voltmeter is accurate, if not, you can calibrate the voltmeter; 3.

Check whether the voltage regulator is normal, if not, you can replace the voltage regulator; 4.Check whether the regulation range of the voltage regulator is sufficient, if not, you can replace the more advanced voltage regulator; 5.Check whether the adjustment accuracy of the voltage regulator is sufficient, and if the spring imitation is not enough, you can replace the voltage regulator with higher precision.

Personal tips: When conducting the AC withstand voltage test, it is necessary to ensure that the power supply voltage is stable, the voltmeter is accurate, the voltage regulator is normal, the adjustment range is sufficient, and the adjustment accuracy is sufficient to ensure the accuracy of the test results.

Hello, I am glad to serve you and give you the following answer: the duration of the AC withstand voltage test is generally 1 minute, but in practice, sometimes the duration is not enough. The solution to this problem is as follows:

1.Check whether the voltage reaches the standard voltage, if not, the voltage can be adjusted appropriately to reach the standard voltage. 2.

Check whether the voltmeter is normal, if not, you can replace it with a new one to ensure the accuracy of the measurement. 3.Check whether the circuit has a short circuit, if so, you can check and replace the parts of the short circuit to ensure the normal operation of the circuit.

4.Check whether the contact of the circuit is good, if it is bad, you can check and replace the parts with poor contact to ensure the normal operation of the circuit. In practice, it is necessary to ensure the normal operation of the voltmeter, circuit and contact to ensure the accuracy of the test.

First, the nature is different.

1. AC withstand voltage: the most effective and direct method to identify the dielectric strength of power equipment.

2. DC withstand voltage: the maximum voltage peak value of the detection equipment under the high voltage test.

Second, the destructiveness of breaking orders is different.

1. DC withstand voltage: Since the insulation under DC voltage basically does not produce dielectric loss, the damage to the insulation caused by DC withstand voltage is small. In addition, since only a small leakage current is required for the DC withstand voltage, the required test equipment has a small capacity and is easy to carry.

2. AC withstand voltage: AC withstand voltage is more damaging to insulation than DC withstand voltage, because the test current is capacitive current, large-capacity test equipment is required.