IEEE Std ™ I. EEE Standards. TM. IEEE Guide for Field Testing of Shielded Power. Cable Systems Using Very Low. “IEEE Guide for Field Testing and Evaluation of the Insulation of Shielded Power IEEE “Guide for Testing of Shielded Power Cable Systems using Very. Guided IEEE Series (Bundle) Standards IEEE – • IEEE Guide for Field Testing of Shielded Power Cable Systems Using Very.
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Once the test lead from the VLF test equipment is connected to the cable to be tested, this safety ground can be removed so that testing can commence. At least one end of the cable must be accessible. A, and Hernandez-Mejia, J. It should be noted that Table 4 to Table 7 apply to maintenance tests on cable systems that have been in operation for five or more years, i. PD sensitivity can decrease with increasing length of the cable under test.
Also included are tables giving limits of the temporal stability of tangent delta, differential tangent delta difference in tangent delta at two test voltagesand absolute values of tangent delta for new and service-aged cable systems.
It is made available for a wide variety of both public and private uses. Users of this standard are expressly advised that determination of the validity of any ieed rights, and the risk of infringement of such rights, is entirely their own responsibility. The columns in Table 4 to Table 7 are arranged in the order of sensitivity of the measurements to 400.2 deterioration, i. NOTE—There have been no cases documented of partial discharge detectable in the field from water trees.
Therefore, caution is recommended in interpretation of results. The issues encountered include: If the circuit fails during the test, it should be repaired or replaced and then retested using a complete minute test, preferably a monitored withstand test.
Because of the sinusoidal transitions between the positive and negative polarities, traveling waves are not generated, and because of continuous ifee changes, space charges are not likely to be developed in the insulation unless the frequency is less than 0. There are two main wave shapes presently in use, the sinusoidal and cosine-rectangular waveforms. This guide addresses VLF ieew voltage withstand and dielectric loss testing in the frequency range from 0.
The safety practices shall include, but not be limited to, the following requirements: The impregnating compound has a sufficiently high viscosity at maximum operating temperature to preclude migration or draining of compound. Some comments on data interpretation and subsequent performance after simple or monitored withstand test are given in Annex F.
Letters of Assurance may indicate whether the Submitter is willing or unwilling to grant licenses under patent rights without compensation or under reasonable rates, with reasonable terms and conditions that are demonstrably free of any unfair discrimination to applicants desiring to obtain such licenses. Lower and upper TD and differential TD limits are individually applied. Once a cable system passes the VLF withstand test, it may be returned to service.
A cable design using impregnated ieee insulation. Time domain reflectometry may be used to determine the location of accessories, open points and the length of the circuit. There are risks associated with high-voltage testing and diagnostics. A traveling wave method may be used to measure the magnitude of PD, locate, and record the partial discharges from the various defect locations in the cable, splices, or terminations. VLF ac voltage testing methods utilize ac signals at frequencies in the range of 0.
Tree-like growths, consisting of non-solid or carbonized micro-channels, that can occur at stress enhancements such as protrusions, contaminants, voids, or water trees subjected to electrical stress.
The VLF ac voltage test set 400.22 turned off to discharge the cable system and test set. Since IEEE standards represent a consensus of concerned interests, it is important to ensure that any responses to comments and questions also receive the concurrence of a balance of interests.
When testing, a single system ground at the test site is recommended, see Figure 1. Typical measurement times take less than 15 min. The tangent delta values of aged extruded and oil-paper insulations usually increase with time but occasionally a decrease occurs. Some tested cable systems, which were already known to have questionable due to age or failures in service service performance, were monitored for a number of years to determine their service performance.
Corrosion of the metallic shield can limit the sensitivity of PD tests due to the attenuation of high frequency signals. After the initiation of PDs PDIVan electrical tree may form that can develop into a breakdown channel within minutes.
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If the individual sections cannot be measured, the test method may not be useful. All cable and equipment tests shall be performed on de-energized and isolated systems except where otherwise specifically recommended and properly authorized. These results may also be used to trigger further testing.
The new iee will be included in future revisions of this document. For new cable systems, the differential tan delta DTD is expected to be small, i.
Cable systems can be tested in preventive maintenance programs and returned to service after testing. 400.2 some equipment, voltage reaches the test voltage in the first cycle so that the ramp is a quarter cycle of the voltage waveform.
VLF cable testing – Wikiwand
Field testing techniques frequently employ a combination of diagnostic test methods. Dielectric losses can be affected by insulation material parameters such as different materials and the iere by-products, although in older cables the concentration 400.2 the latter will be negligible. IEEE does not, by the publication of its standards, intend to urge action that is not in compliance with applicable laws, and these documents may not be construed as doing so.
Obviously the 95th percentile Action Required is the level that is most sensitive to iese issue as this is at the extreme of the data distribution. In addition, some utilities may have components connected to the cable circuit being measured, e. The test is intended to detect installation damage and to show any gross defects or errors in installation of other system components.
The values may change as additional isee are accumulated. Portable ground clamps and grounding assemblies built and tested per IEC are recommended. Regarding the test times: Monitoring the future performance of tested circuits will help to strengthen or modify the correlations as more data are acquired.
A comparison of data from similar cable systems should improve the usefulness of tests.