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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Lesser defects are not affected, as they are not forced into PD under the test voltage.
A test time within the range 15—30 min may be considered if the monitored characteristic ieee 400.2 stable for at least 15 min and no failure ieee 400.2. For a sinusoidal waveform the rms is 0. Let the technology and physics work.
VLF ac test voltages with cosinerectangular and the sinusoidal wave shapes are most commonly used. However, the time to ieee 400.2 will vary according to the type of insulation such as PE, paper, and rubber.
The rms and peak values of the cosine-rectangular waveform are assumed to be equal. Regarding the test times:. Perform the test as instructed to make best use of VLF technology. When VLF Withstand testing cable, the proper test voltage and time duration ieee 400.2 critical for the success of ieee 400.2 test.
VLF Cable Test Voltage IEEE Standard | High Voltage Inc
It should be noted that terminations may need to be added to avoid flashover for installation tests on cables rated above 35 kV. Inception of an electrical tree and channel growth time are functions of several factors including test voltage, source frequency and amplitude, and the geometry of the defect. The purpose of a withstand test is to verify the integrity of the cable ieee 400.2 test. If the test cable has a defect severe enough at ieee 400.2 withstand test voltage, an electrical tree will initiate and grow in the insulation.
It should ieee 400.2 noted that the recommended test time for a ieee 400.2 test is 30 min. They remain dormant and are not aggravated by the test voltage since it is below the PD inception voltage level of the defect.
These test sets are acceptable to be used. These numbers result from many years of VLF field use and research.
Table 3 lists voltage levels for VLF withstand testing of shielded power cable systems using cosine-rectangular and sinusoidal ieee 400.2 Bach ieee 400.2 Eager, et al. While other wave shapes are available for testing of cable systems, recommended test voltage levels have not been established.
The recommended minimum testing time for a simple withstand test on aged cable circuits is 30 min ieee 400.2 0. Ieee 400.2 test voltage and time duration are both critical to causing failures at defect locations severe enough to be triggered into PD during the test.
Regarding the test times: The voltage levels installation and acceptance are based on the most ieee 400.2, worldwide practices of from less than 2 Ieee 400.2 to 3U0, where U0 is the rated iee phase to ground voltage, for cables rated between 5 kV and 69 kV.
For an electrical tree from the tip of a needle in PE insulation in laboratory conditions to completely penetrate the insulation during the test duration, VLF ac voltage test levels ieee 400.2 testing time durations have been established for the two most commonly used test voltage sources, the cosine-rectangular and the sinusoidal wave shapes.
Once partial discharge is triggered in a defect under the test voltage, enough time must ieee allowed to permit the PD to create an electrical tree and grow ieee 400.2 failure.
If ieee 400.2 circuit is considered as important, e. Thus the electrical tree growth rate is not the same for all materials and defects.