Introduction To The Basic Concepts Of Insulators That Are Different From Ordinary Products

The discharge characteristics of Arrester are different under power frequency voltage, switching overvoltage, and lightning overvoltage. For insulation coordination under power frequency voltage, generally only creepage distance is required to meet the requirements. After all, power frequency voltage is applied to insulators for a long time. The discharge characteristics of switching overvoltage and lightning overvoltage are mainly affected by the length of the insulator string. Among them, the switching overvoltage is an internal overvoltage, so the influence of tower height is not considered, while the lightning overvoltage is an external overvoltage, and the tower height must be considered. Insulator In addition, the overvoltage waveform of the switching overvoltage is closer to the waveform of the power frequency voltage, so the zero-value insulator will affect its discharge characteristics. Therefore, when calculating the tension insulator under the switching overvoltage, it is necessary to consider adding a certain number of zero-value insulators more than the suspension string; and the lightning overvoltage mainly considers the effective string length because the discharge time is extremely short. The zero-value insulator will not reduce the effective string length of the insulator string, so it is not necessary to consider adding zero-value insulators when performing insulation coordination for lightning overvoltage. 1. For operating overvoltage, meet the minimum requirements of Table 7.0.2. This table is actually for verification, because it does not give you the multiples of the operating overvoltage and the discharge characteristics of the insulator under the operating overvoltage. You cannot look up the table to obtain the insulator length and then calculate the number of pieces. If it is tension-resistant, you need to add zero-value pieces. Regardless of the height of the insulator string, the equivalent length of the insulator string after the zero value fails must meet the string length required by this table. This is the minimum required string length when there is no zero value. Under plain conditions, the tower height does not affect the discharge characteristics of the insulator under operating overvoltage and the value of the overvoltage, so there is no need to correct the tower height for the operating overvoltage. 2. For power frequency voltage, it is only necessary to meet the creepage distance, and the creepage distance method can be used for suspension and tension! This method does not require tower height correction or zero value correction. 3. For lightning overvoltage, when the tower height is less than 40 meters, the length of the insulator string must meet the minimum requirements of Table 7.0.2; if the tower height exceeds 40 meters, the tower height must be corrected. The corrected insulator string length is the length required for lightning overvoltage. This length can be used to convert the number of insulator pieces to be used.