Impact of time parameters of lightning impulse on the breakdown characteristics of oil paper insulation

Abstract

At present, the insulation performances of electrical apparatus under lightning impulse voltages are always evaluated by the withstand test of standard lightning impulse voltage (1.2/50 µs), which is recommended by IEC Standard. However, the actual time parameters of transformer invading lightning impulse voltage present an obvious dispersibility characteristics. The standard wave shape is only representative of one particular class of lightning waves, which is far from satisfactory to act as the guidance waveform in the design of power equipment insulation. On the basis of the above research background, the relationship between breakdown characteristics of oil paper insulation and time parameters of applied lightning impulse voltage was investigated in this study. The 50% breakdown voltage characteristics of oil paper insulation under lightning impulse voltage with different time parameters were determined. The test results indicate that a short wave front time could lead to relatively low 50% breakdown voltage, while when the wave tail time varied, the 50% breakdown voltage of oil paper insulation barely changed. At last the simulation model of oil paper insulation was developed, and the current flowing through the oil paper insulating system under lightning impulse voltage was calculated. On the basis of the simulating results, the relationship between current and time parameters was analysed.

Breakdown Voltage and Its Influencing Factors of Thermally Aged Oil-Impregnated Paper at Pulsating DC Voltage

“…The breakdown voltage of OIP or oil-paper insulation has been widely studied at various voltage waveforms, including AC voltage [11,12], DC voltage [13,14], impulse voltage [12,[15][16][17][18], and pulsating DC voltage [6,19,20]. In [6], the breakdown voltage of OIP at pulsating DC voltage (with a ripple factor of 1 and 1/3) was measured.…”

Influence of Standard Lightning Impulse Front Time Tolerances on the Flashover Voltage of Suspension Insulators

“…If testers start to intentionally favor shorter T1 times (< 1 µs) in order to pass test requirements, is the procedure representative of natural lightning stress? Numerous authors [3,[7][8] have measured natural lightning waveforms with T1 values ranging up to tens of microseconds and T2 values extending to 200 µs (observations vary based on conditionsdistance to measurement location, voltage class, system conditions, etc.). To account for these longer time parameters, should positive tolerances for T1 be extended further and negative tolerance be removed (e.g., T1 = 1.2 µs +50%, -0%)?…”

“…According to historical reviews [3,7], the need for a standard lightning impulse waveform was first expressed in the 1920s. The impulse waveform went through several different formats as more experimental data was acquired.…”

Suppressing Arc Development by Arc‐Extinguishing and Lightning‐Protection Device

“…Traditional intercept‐type lightning‐protection measures have a certain inhibiting effect on overhead transmission lines struck by lightning, but the lightning‐protection effect is not obvious for areas where the line is located in areas with frequent lightning events, mountains, and areas with high ground resistance. So, we should adopt a new way, such as a parallel gap, when lightning hits overhead transmission lines . Because the insulation level of the insulator string is higher than that of the parallel gap, the parallel gap will first break down and leak the lightning current into the earth; so a parallel gap protects the insulator string but does not break down, which ensures the safe operation of lines and electrical equipment.…”