IEEE 1234-2019 pdf download

IEEE 1234-2019 pdf download.IEEE Guide for Fault-Locating Techniques on Shielded Power Cable Systems
5. Safety
5.1 Safety practices
When testing a cable system, personnel safety and service relability of the electrical systerms are of ultimate importance. All cable and equipment tests shall be performed on isolated and de- energized systems, except  here otherwise specifically required and authorized. The safety practices shall include, but not be limited to,the following requirements:
a) Applicable user safety operating procedures
b) IEEE Std510TM, IEEE Recommended Practices for Safety in High-Voltage and High-Power Testing’
c) Applicable state and local safety operating procedures
d) Protection of utility and customer property
While testing, one or more cable ends will be remote from the testing site, therefore:
-Cable ends shall be cleared and guarded.
-Communications shall be maintained with personnel at the remote end at all times.
-Cables shall be de-energized and grounded before testing is begun.
FAny cables andor conductors not under test shall be solidly grounded during testing.
At the conclusion of high-voltagc testing, attention should be given to:
Special techmiques required for discharging cables and cable systems t0 dissipate any stored energy that may be present in the cable.
Grounding requirements for cables to assure that adequate time is given to completely discharge the
trapped charges that can exist in a cable duc to diclectric absorption.
5.2 Precautions for ac cable systems Many cable fault locators and troubleshooters use high-voltage de as part of their standard fault-locating procedure. It is known that dc testing may generate additional cable defects in service- aged ac cables with extruded diclectric insulation, in particular, XLPE. Therefore, dc proof testing of service-aged cables with extruded dielectric insulation is not recommended. This precaution does not apply to de cable systems or paper-insulated cables. Failure to completely discharge a cable afer it has been charged with voltage may result in failure upon re- energization.
Due to trapped charges, which have a long discharge time constant, the residual dc voltage may cause a failure upon re-energization. See the IEEE Std 400TM omnibus. Some utility or industrial standards do not yet take into account the potentially damaging efects of dc testing on extruded cables used in ac systems. If dc testing should become necessary, the cable manufacturer should be consulted for the maximum dc test value. This restriction does not apply to cables with laminated, oil- impregnated-paper-type insulation. There is a key difference between what is considered a de cable test and an applied dc voltage during fault locating. As stated, it is not recommended to de test an extruded cable.
Typically when fault locating, a de voltage is applied when using the thumper method to determine the breakdown voltage of the fault. This information is then used to determine the proper thump voltage level to use.
This process of stting the thump voltage takes just a few seconds, as opposed to dc cable testing which is typically a minimum of 15 minutes in duration. Reducing the thump voltage and the number of times a cable is thumped can also be achieved by one of the arc reflection methods discussed in Clause 7.
DC voltagc sources are also used as part of some fault-locating techniques including the bridge methods, current tracing methods, metallic shield/sheath, and jacket (oversheath) fault locating. Again, these methods typically apply a de voltage less than the peak of the ac operating voltage for a short time duration. Conected equipment and the cable terminal voltage ratings should be considered before applying a de test voltage. Special consideration should be given if there are gas-insulated cable terminations. When testing a faulted cable, be cautious of induced voltage from parallel transmission circuits. Please refer to IEEE Std 1727TM.IEEE 1234 pdf download.IEEE 1234-2019 pdf download