NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
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NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
Author: Noyafa–Cable Tester Manufacturer
What are the regulations for the DC withstand voltage test of the cable fault tester? 1. When testing the main insulation DC withstand voltage or insulation resistance of the cable fault tester is measured by a DC high voltage generator, it should be carried out separately on each phase. When testing or measuring one phase, what are the provisions for the DC withstand voltage test of another cable fault tester? 1. When the main insulation DC withstand voltage or insulation resistance of the test cable fault tester is measured by a DC high voltage generator, it should be carried out separately on each phase. When testing or measuring one phase, the other two-phase conductor, the metal shield or metal sleeve and the armor are grounded together.
2. The test results are abnormal, but the test period should be shortened according to the comprehensive judgment of the cables that are allowed to continue to run. If the test results are good after more than 3 consecutive tests for not less than 6 months, the test results will be tested on the normal cycle. 3. The newly laid cable fault tester is put into operation for 3 to 12 months.
Usually, the DC high voltage generator is used for 1 DC withstand voltage test and then tested according to the normal cycle. 4. When one end of the metal shield or metal sleeve is grounded, and the main insulation of the single-core cable and the overvoltage protector at the other end are used for the DC withstand voltage test, the overvoltage protector must be short-circuited. Make a cable for this.
The metal shield or metal sleeve is temporarily grounded. 5. After the DC high voltage generator is subjected to the withstand voltage test, when the conductor is discharged, it needs to pass about 80k per kilovoltΩThe current-limiting resistor is repeatedly discharged several times until no spark is applied, then the discharge is allowed directly to ground. 6. For cables with a rated voltage of 0.6/1kV, the insulation resistance of conductors to ground can be measured by a 1000V or 2500V megohmmeter instead of a DC withstand voltage test.
7. In the DC withstand voltage test, the leakage current should be measured 1 minute after the test voltage rises to the specified value and when the pressing time reaches the specified value. The leakage current value and unbalance factor are only used as a reference for judging the insulation state, not the standard for whether it can be put into operation. However, if the leakage current is found to be very different from the previous test value, or the leakage current is not stable and the voltage rises sharply as the test voltage increases or the pressurization time increases, the cause should be determined.
If it is caused by leakage current on the terminal surface or ground stray current, it should be eliminated; if it is suspected that the cable has poor line insulation, the test voltage can be increased (not to exceed the factory test DC voltage specified in the product standard), or it can be extended Test time to see if it can continue to run. 8. Except for the self-provided cable fault tester, other cable fault testers must be in good condition before being put into operation after a power failure. For cable lines that have been out of power for more than a week but less than a month, use a megohmmeter to measure the insulation resistance of the cable conductors to ground.
When in doubt, the test must be performed with a DC voltage lower than the conventional DC withstand voltage.
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