IEEE 400.1-2007 pdf free download – IEEE Guide for Field Testing of Laminated Dielectric, Shielded Power Cable Systems Rated 5 kV and Above with High Direct Current Voltage.
4. Test procedure
4.1 Test precautions
the following precautions should be considered when tests with high Uc voltage in the field.
— All coniponenL’. require de•energwing and solid grounding before testing Checking with a reliable voltage indicator that responds to alternating current (ac) and & voltage is recommended. While the indicator is in contact with each component and indicates no voltage, a ground connection should be applied to the component and remain attached at all times except when the test voltage is being applied. All uncnergired metallic parts in the vicinity of the high. voltage connections should always remain grounded.
— All cable termination ends as well as all connecting leads of components being tested require guarding from accidental contact by such means as barriers, enclosures, or a watchman at all points. The cabk’ ends require separation from all elements not to be subjected to test and by distances at leasi 025 cnVkV 10.1 inkV) of test potentsal for voltages up to lOt) kV and at least OS cinkV (0.2 in’kV) for higher test voltages. Please note that the test electrode geometry has a great influence on the safety clearances, The values recommended in this paragraph are only for conditions where high-voltage and ground electrodes are smooth and unifoms and where high- voltage connections arc made with round conductors of adequate sire to avoid corona If the test connections are not snsooth, larger clearances should be provided.
— Breakdown or tenmnal flaxhoser may generate traveltng waves up and down the cable that can be of a magnitude great enough to cause degradation of the insulation of the cable or accessories or breakdown of the insulation. Consideration should be given to the installation of suitable rod gaps according to IEEE Std 4 lix dc voltages to provide protection. A damping resistor rated for the voltage and energy of the cable can be installed in the series circuit to reduce oscillations and reflection voltages.
— For circuits with open-circuit (split) shields, the shield gaps should be short circuited tjumpered comsectionf, and this jumper conductor connected to grounrL .Surge protectors should be disconnected and grounded. Grounding in this manner reduces ovrrvoltages on gap insulation and surge protectors in the event of a test failure.
High direct voltage field-testing of cable systems involves all of the concerns normally associated with working on energized circuits, as well as several unique concents that must be addressed. Cable circuits will normally have one or more ends remote from the location of the test equipment said the test operator. Tlsese ends must be cleared and guarded to ensure the safety of personnel. Reliable voice communication should be established between all such locations and rIse test operator.
— Cables have high capacitance and dielectric absorption characteristics with long time constants. Particular attention must be directed to the special techniques required for discharging cables after testing to minimize the possibility of personal iisjury 4.2 Safety practices
When testing. personnel safety and sen-icc reliability of the electrical systems are of ultimate importance. All cable and equipment tests must be perfonned on isolated and de’enersjired systems escept where otherwise specifically required and authorized. The safety practices should include at least the following requirements:
a) Applicable user safely operating procedures.
hi Recommended practices for safety in high•soltage testing (see IFEF. Ski 510.19)0).
ci Applicable state and local governing safety operating procedures.
d) Part 4 of the National Electrical Safety Cosleic (NFSC*i(Accredited Standard’. Committcc C2• 2002) where applicable.
ci Protection of utility and c-u.skicnsT property by such means a.’. IMmers. enclosures with warning signs, and safety watchers at all points. The test program of each safety system should be designed to provide for minimum interference, as much as practicable. with related operations channels, systems, or equipment.
I) Cables tmist be de•energized and pounded before waling is begun.
g) While testing. one or more cable ends will be remote from the testing site; therefore cable ends must he cleared and guarded
hi At the conclusion of high-voltage testing. cables and cable systems should be discharged and careful consideration must he given to eliminate the afterel’fects of the cables’ dielectnc absorption and capacitance characteristics. Those effects can be reduced isv leaving both the conductor and sheath of the cable pounded until it is placed in sen ice.
4.3 Testing procedure
Disconnect all equipment nut to he included in the test, but leave all ground connections intact Any temporary struts, ties, leads, spacers, and terminations or connecting leads must be capable of sustaining the test voltage withottt undtie leakage or heating. Prepare the cable system for testing in accordance with manufacturer or utility recommendations. Clean insulator surfaces with a dry cloth and, if necessary (in severely polluted areas), apply silicone grease to minimize leakage currents and prevent Ilashover, An output conncction is required to connect the power supply to the termination of the cablc under test. This conntctioli should he smooth and free of surface irregularities if possible.
The test lead itself as well as the entire measuring circuit should he corona-free. If a bare conductor is used, it should be of a sufficient diameter to prevent partial discharges icorona) from its stirface, A general guideline of 2.5 cm (I in) conductor diameter for every 100 kV of test voltage is usually sufficient for smooth conductors arid cable terminations with stress relief electrodes. If an insulated conductor is used, the insulation should be thick enough or have a large enough diameter to prevent pinholes from developing. due to the cstemal field that would cause corona. If a shielded conductor is used, its insulation and terminations should be adequate to withstand the test voltage, and the shield should be at ground or at the tesi equipment guard potential.IEEE 400.1 pdf download.