Guideline for On-site Insulation Test Implementation DL/T474.1-DL/T474.5-2006

Author: Compiled by the Press
Publisher:
Publish Date: 2006-09-01
Features:
Insulation Resistance, Absorption Ratio, and Polarization Index Tests: This standard was revised according to the arrangement in the "Notice of the General Office of the National Development and Reform Commission on Issuing the 2005 Industrial Standard Project Plan" (No. 739, Guifan Gongye [2005]) and was based on DL474.1-1992. DL474.1-1992 "Implementation of Insulation Resistance, Absorption Ratio, and Polarization Index Tests in Field Insulation Tests" was compiled by experts in China's power industry based on years of field work experience. This revision only made partial updates considering the alignment with current relevant standards, the status of updated test instruments, and new issues encountered in field tests. Corresponding corrections were made to individual wording and printing errors.
DC High Voltage Measurement Difficulty: This standard was revised according to the arrangement in the "Notice of the General Office of the National Development and Reform Commission on Issuing the 2005 Industrial Standard Project Plan" (No. 739, Guifan Gongye [2005]). Compared to the original standard, the main changes are as follows:
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- The original standard's requirements for the accuracy of DC high-voltage measurement were changed from measurement error to permissible deviation, aligning with GB/16927.1~2 High-Voltage Test Technology;
- Added content on the calibration of DC complete equipment, including voltage-current characteristics, stability, and calibration cycles;
- The wiring diagram for microammeters was revised to be more suitable for field tests;
- New specifications were introduced for the insulation strength of high-voltage protection voltage resistors in the original standard to accommodate different types of protection resistors;
- The original standard's "pulsation factor" was standardized to "ripple factor";
- The standard's "pulsating voltage" was standardized to "ripple," aligning with GB/T2900.19 Electrical Terms High-Voltage Test Technology and Insulation Coordination.
The book also includes "Dielectric Loss Factor tan Tests," "AC Withstand Voltage Tests," and "Surge Arrester Tests."