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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These are set out below, using the filled insulation, and its sub-classes, as an example. Complete insulation breakdown may subsequently occur if a water tree either induces an electrical tree and the electrical tree ieeee a channel of sufficient length to fail the insulation or leads to thermal runaway.
There is no evidence of partial discharge see NOTE inside the water tree branches. Moreover it should be noted that PD inception conditions at VLF can be different from those at other frequencies. Whenever possible, cable systems are treated in a similar manner to individual cables.
If a high value of loss is detected, then a oeee has a number of choices as follows: The values in Table 4 to Table 7 were derived from empirical cumulative distribution functions CDF for the data consisting of data points obtained for aged cable systems, mainly in utilities from North America, i.
The values given in Table 4 to Table 7 can also be given in percentage, in which case the values are multiplied byfor example, 0. It should also be noted that tangent delta measurements in aged cable systems are sensitive to water tree degradation; whereas, such measurements in acceptance tests on new cable systems are looking for contamination, etc.
Cable systems can be tested after installation, for acceptance, or in preventive maintenance programs or after outages. If a circuit is considered as important, e. Typical measurement times take less than 15 min.
VLF cable testing – Wikiwand
For example, a short length of cable or an accessory could have a high loss whereas the rest of the circuit has low losses, or severe metallic shield corrosion could affect the tangent delta measurements.
However, the test may detect a wet or lossy accessory in new Baur [B5] or aged cable systems. The variation of tangent delta iee test voltage is also sensitive to insulation aging. Cables ,Medium, and High Voltage. Users may use their own cumulative measurement data and percentile values to develop their own ieef of merit for the different types of cable systems.
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 ieed as doing so. Again this is a judgment guided by the remediation and risk strategies. Within the water tree the insulation is degraded due to chemical modification in the 400.2 of moisture.
Reference to these resources is made for informational use only. IEEE disclaims liability for any personal injury, property or other damage, of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, or reliance upon any IEEE Standard document.
VLF ac voltage testing is an alternative method of continuous ac voltage testing and is used iee a broad range of accessory and cable types Kobayashi, et al. Therefore, caution is recommended in interpretation of results. The tangent delta values of aged extruded and oil-paper insulations usually increase with time but occasionally a decrease occurs.
During the test other properties of the test object are monitored and these are used, together with the withstand results, eiee determine its condition.
As the data available in from VLF diagnostic tests on the different types of newly installed cable systems ieeee limited, the figures of merit for new cable systems are listed in Table G. 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. The measurement of the test voltage should be made with an approved and calibrated measuring system as described in IEC When the cable or cable system passes the VLF voltage test, the test voltage is regulated to isee and cable and test set are discharged and grounded.
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The criteria used for the historical figures of merit provided in this document have been selected using the estimate of ieee 80th and 95th percentiles, not the lower confidence limits. In withstand testing, Gnerlich [B11]the test object must survive a specified voltage applied across the insulation for a specified period of time without breakdown of the insulation Hampton, et al. The results of these tests will assist in assessing the severity of the cable condition and give guidance in determining the duration of the withstand test.
The most commonly used, commercially available VLF ac voltage test frequency is 0. For this reason, IEEE and the members of its societies and Standards Coordinating Committees are not able to provide an instant response to comments or questions except in those cases where the 400.22 has previously been addressed. Nor is IEEE undertaking to perform any duty owed by any other person or entity to another. A comparison of data from similar cable systems should improve the usefulness ieer tests.
Click here to sign up. Each length tested is different from others dependence in the same area. In addition, some utilities may have components connected to the cable circuit being measured, e. A correlation between an increasing 0. Monitoring the future performance of tested circuits will help to strengthen or modify the correlations as more data are collected.
The Working Group would also like to thank EPRI for allowing the use of its data to expand the data base thus allowing greater precision in the data. The positive and the negative halves of the output waveform should be symmetrical.
If PDs occur, the voltage is maintained for an additional 30 s to 60 s and then slowly reduced until the PDs extinguish. The change in the tangent delta with time at constant voltage increases with degree of aging of the insulation. Suggestions for changes in documents should be in the form of a proposed change of text, together with appropriate supporting comments.
For new cable systems, the voltage sensitivity of the tangent delta, the differential tangent delta DTDis expected to be small, as should the temporal stability of tangent delta at constant voltage TDTS. Furthermore, the viewpoint expressed at the time a standard is approved iree issued is subject to change brought about through developments in the state of the art and comments received from users of the standard. The described method is based on the application of a pure, sinusoidal 0.