Rated lightning impulse withstand voltage

1 Topic Content and Applicability Scope 

    This standard specifies two testing methods, namely, MethodAPlease provide the Chinese content to be translated.BInsufficient Chinese content provided for translation. Please provide the complete news content in Chinese for accurate translation into American English. Electrical strength in a field subjected to standard lightning strikes. 

    MethodA—— Step-by-Step Testing Method: Used to provide the breakdown voltage of insulating liquids under specific conditions, due to lightning impulse The estimated value. 

    MethodB——Sequential Testing Method: A statistical testing method used to examine insulating fluids under a specific Assumption of breakdown probability under the impact of lightning impulse voltage. 

    This standard applies to both used and unused insulating liquids. The tested insulating liquids include:40Unfortunately, the provided text "℃时的粘" does not contain sufficient information to be translated accurately into English. It appears to be a fragment of a sentence or term that is likely related to temperature and viscosity in a technical context. Could you please provide the full news content or clarify the intended meaning so I can provide an accurate translation? Degree should be lower than700mm2/s。 

    Two methods can utilize both positive and negative polarity impacts. However, they are used to judge the chemical composition's effects on insulating liquids. When considering the effect of electrical impulse breakdown voltage, it is advisable to use negative polarity impulses. 

    These two methods are primarily used to establish standard procedures for assessing the lightning impulse breakdown voltage of insulating liquids. They both Available for assessing the lightning impulse characteristics of insulating liquids, as well as changes in production processes, composition, or oil sources. Variation in the breakdown voltage values due to lightning impulse. 

2 Citing Standards 

    GB 311.1～311.6 Insulation Coordination for High-Voltage Transmission and Transformation Equipment 

    GB 7597 Petroleum for Power Use(Transformer Oil, Turbine Oil)Sampling Method 

3 Significance 

3.1 Insulating liquids used in electrical equipment may need to withstand transient voltages superimposed on the power frequency voltage during operation. The effect of operating voltage or lightning impulse voltage. 

    Transient voltages, whether unidirectional or oscillating, will inevitably result in either a positive or negative polarity. The transient voltage action process. Therefore, it is necessary to understand the characteristics of the insulating liquid under these conditions. 

    However, when using a needle in the oil sample cup...-Ball electrode experiments were conducted to obtain the breakdown voltage and actual insulation system. The relationship between the breakdown properties of insulating liquids and the dielectric strength still requires further investigation. 

3.2 Insulation fluids' dielectric breakdown is a complex phenomenon that has yet to be fully understood. In summary, breakdown requires excitation The propagation of emitted and pre-breakdown disturbances(Stream Column)。 

    Due to the fact that breakdown voltage depends on factors such as voltage waveform, the duration of voltage application, and electric field distribution, therefore, to achieve To comparable results. All these factors must be clearly defined and strictly controlled. Despite this, the conclusion There may still be considerable dispersion, which can be attributed to the randomness associated with the pre-breakdown mechanism.