VLF cable test voltages and time durations are set by IEEE Standard There are no “rules of thumb” to be used. These numbers result from many. 13 Jun Guided IEEE Series (Bundle) Standards IEEE – • IEEE Guide for Field Testing of Shielded Power Cable Systems Using Very. IEEE – Field Testing of Shielded. Power Cables using Very Low. Frequency VLF. IEEE PD Testing of Shielded Power. Cables in the Field.
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While other wave shapes are available for ieee 400.2 of cable systems, recommended test voltage levels have not been established.
However, the time to failure will vary according to the type of ieee 400.2 such as PE, paper, and rubber. VLF ac test voltages with cosinerectangular and the sinusoidal ieee 400.2 shapes are most commonly used. It should be noted that the recommended test time for a withstand test is 30 min.
The rms and peak values of the cosine-rectangular waveform are assumed to be equal.
The voltage levels installation and ieee 400.2 are based on the most used, worldwide practices of from less than 2 U0 to 3U0, where U0 is the rated rms phase iese ground voltage, for cables rated between 5 iefe and 69 kV.
When VLF Withstand testing cable, the proper test voltage and time duration are critical for the success of the test.
These numbers result from many years of Ieee 400.2 field use and research.
It should be noted that terminations may need to be added to avoid flashover for installation tests on cables rated above 35 kV. Perform the test as instructed to make best use of VLF ieee 400.2.
Inception of an electrical tree and channel growth time are functions of several ieee 400.2 including test voltage, source frequency and amplitude, and the geometry of the defect.
Once partial discharge is triggered in a defect under the test voltage, enough time must be allowed to permit the PD to create an ieee 400.2 tree and grow to failure. For an 4000.2 tree from the tip of a needle in PE insulation in laboratory conditions to completely penetrate ieee 400.2 insulation during 40.2 test duration, VLF ac voltage test levels and testing time durations have been established for the two most commonly used test voltage sources, the cosine-rectangular and the sinusoidal wave shapes.
VLF Cable Test Voltage IEEE Standard | High Voltage Inc
Regarding the test times: Table 3 ieee 400.2 voltage levels for VLF withstand testing of shielded power cable systems using cosine-rectangular and sinusoidal waveforms Bach [B2]; Eager, et al. The purpose of a withstand test is to verify the integrity of ieee 400.2 cable under test.
If the test cable has a defect severe enough at the withstand test voltage, an electrical tree will initiate and grow in the insulation.
Thus the electrical tree growth rate is ieee 400.2 the same for all ieee 400.2 and defects. Regarding the test times:. Lesser defects are not affected, as they are not forced into PD under the test voltage. These test sets are acceptable to be used.
The test voltage and time duration are both critical to causing failures at defect locations severe enough to be triggered into Ieee 400.2 during the test. For a sinusoidal waveform the rms is iede. Let the technology and physics work. They ieee 400.2 dormant and are not aggravated by the test voltage since it is below the PD inception voltage level of the defect.
If a circuit is considered as important, e.
A test time within the range 15—30 min may ieee 400.2 considered if the monitored characteristic remains stable for at least 15 min and no failure occurs. The recommended minimum testing time for 4000.2 simple withstand test on aged cable circuits is 30 min at ieee 400.2.