Insulation Resistance Tester
The insulation resistance tester (also known as a digital megohmmeter, high-resistance meter, or digital "shake meter") is a core tool for evaluating the insulation performance of electrical equipment. It applies a high DC voltage to the object under test and measures the resulting weak leakage current, thereby calculating the insulation resistance value. It is widely used to identify hidden hazards such as moisture, aging, or partial discharge in equipment.
Combining the latest industry standards and selection logic, we have compiled a practical procurement and usage guide for you:
I. Core Selection Parameters: 4 Hard Indicators That Must Be Checked
1. Test Voltage Level Matching
The test voltage must match the rated voltage of the equipment under test. According to relevant electrical test regulations, the selection reference is as follows:
Equipment/circuits below 100V: Use the 250V range.
100V~500V equipment (such as 220V/380V low-voltage distribution lines): Use the 500V range.
500V~3000V equipment (such as AC motor rotors): Use the 1000V range.
3000V~10000V equipment (such as high-voltage transformers): Use the 2500V range.
Equipment of 10000V and above: Use the 2500V or 5000V (or even higher) range.
2. Range and Short-Circuit Current
Range selection: The range should meet the measurement requirements and leave a margin. For example, the range for 100V~500V equipment should be ≥100MΩ, and the range for 3000V~10000V equipment should be ≥10000MΩ.
Short-circuit current: For large-capacitance equipment such as transformers and power cables, the short-circuit current should not be less than 2mA; when testing large capacitive equipment, it is recommended to choose a model with a short-circuit current above 5mA to ensure fast charging and accurate measurement.
3. Diagnostic and Auxiliary Functions
Insulation trend analysis: When evaluating moisture or aging in the insulation of large equipment (such as generators and transformers), it must have the function of automatically calculating the polarization index (PI) and dielectric absorption ratio (DAR).
Safety and protection: It must have automatic discharge after testing, live circuit detection (to prevent accidental testing on live circuits), and overvoltage/short-circuit protection functions.
Data management: Models that support data storage and USB/Bluetooth transmission are preferred, making it easier to generate trend analysis reports.
4. Environmental Adaptability and Safety Certification
Outdoor or harsh environment operations require an IP54 to IP65 protection rating.
The safety rating should reach CAT IV 600V or above to ensure operator safety.
II. Reference to Mainstream Market Brands and Models
Currently, insulation resistance testers on the market are divided into top international brands and domestic high-cost-performance brands:
Mainstream international brands:
Fluke: Such as Fluke 1508 IND (suitable for routine industrial use, 5-year warranty), Fluke 1535/1537 (supports multiple adjustable ranges from 250V-2500V, automatically calculates PI/DAR, suitable for solar energy and industrial sites).
Megger: Such as the S1 series (S1-568/1068/1568), with extremely strong noise immunity and support for test voltages up to 15kV, suitable for high-voltage transmission and complex substation environments.
High-quality domestic brands:
UNI-T: Such as the UT511/UT512/UT513 series, covering multiple voltage ranges from 100V-5000V, with automatic range and data storage functions, and extremely high cost performance.
Zhuoya Electric Power / Jiangsu Jiuyi: Provide a wide voltage selection from 2500V to 20kV, support continuously adjustable voltage and simultaneous temperature and humidity collection, suitable for large-scale power maintenance.
III. Recommended Local and Surrounding Manufacturers in Yangzhou
Yangzhou (especially Baoying County) is an important industrial belt for domestic power testing instruments, with mature supporting facilities and convenient procurement:
Yangzhou Jinli Electric Co., Ltd.: Specializes in the production of insulation resistance testers, DC high-voltage generators, variable-frequency series resonance and other high-voltage testing equipment, and has accumulated rich experience in software, hardware, and electrical control.
Yangzhou Pengxiang Electric Co., Ltd.: Mainly engaged in high-voltage testing instruments, with a complete and scientific quality management system, and products covering insulation resistance testers and various power testing equipment.
Yangzhou Zhili Electric / Yangzhou Hengwei Electric Heating Technology: In addition to their main business in electric heaters, these two companies also have the capability to supply high-voltage testing instruments, suitable for customers with comprehensive procurement needs for "heating + testing."
IV. Safe Operation and Routine Maintenance Specifications
Key Points for On-Site Operation
Power-off and voltage verification: Before testing, it must be confirmed that the equipment under test is completely powered off, and voltage verification must be performed.
Correct wiring: Ensure that the L (line), E (ground), and G (shield) terminals are correctly connected, and dedicated high-voltage insulation test leads should be used.
Discharge after testing: After testing is completed, the instrument will automatically discharge, but before removing the test leads, it is still necessary to confirm that the equipment under test has no residual voltage at all.
Maintenance and Care
Battery management: Be sure to remove the battery when not in use for a long time to prevent leakage from damaging the instrument's internal circuits.
Moisture and dust protection: Precision instruments should be stored in a dedicated dry and ventilated box, and avoid long-term storage under extreme temperatures (such as below -20°C or above 55°C).
Regular calibration: It is recommended to send the instrument to a qualified metrology institution every year for calibration to ensure measurement accuracy.
