[Technology Program] The insulation performance of insulation materials and electrical equipment has several measurement indicators.

The quality of insulation materials and the insulation performance of electrical equipment are generally measured by their electrical, mechanical, physical, and chemical properties. The quality and service life of electrical products largely depend on these properties of insulation materials. Because the heat resistance, mechanical strength, and lifespan of insulation materials are generally lower than those of metal materials, insulation materials are the weakest link in electrical products, and many faults occur in the insulation part.

Insulation resistance is usually measured to reflect insulation performance. In addition to insulation resistance (IR), there are comprehensive indicators such as polarization index (PI), dielectric absorption ratio (DAR), step voltage (STEP), ramp voltage (RAMP), and dielectric discharge index (DD), which fully reflect the insulation performance of insulation materials and equipment.

1.Insulation Resistance (IR) Measurement:
The principle of insulation resistance measurement is that a high-voltage generator generates a voltage V, which is applied to the two ends of the resistor to be tested. The current I passing through the resistor is measured, and then the resistance value R is calculated according to Ohm's law. R = V/I.

2.Polarization Index (PI) Measurement:
The polarization index is the ratio of the insulation resistance measured within 10 minutes to the insulation resistance measured within 1 minute. The polarization index test takes 10 minutes. When the insulation test time is 10 minutes or longer, the polarization test will be completed and saved. In the setting of the measurement mode, the PI calculation formula can be optionally selected.

    
 

Polarization Index（PI）	＞4	4～2	2.0～1.0	＜1.0
Insulation Condition	Excellent	Good	Fair	Poor

3.Dielectric Absorption Ratio (DAR) Measurement:
The dielectric absorption ratio refers to the ratio of the insulation resistance measured within 1 minute to the insulation resistance measured within 15 seconds. The DAR test is completed within 1 minute. Therefore, for all insulation tests lasting less than 1 minute, the measurement data will be stored as invalid data. When the insulation test time is 1 minute or longer, the DAR is saved in the test results. In the setting of the measurement mode, the DAR calculation formula can be optionally selected.

Dielectric Absorption Ratio（DAR）	＞1.4	1.25～1.0	＜1.0
Insulation Condition	Excellent	Good	Poor

4.Ramp (RAMP) Measurement:
The ramp test mode is an automated testing process. Once the test begins, the output voltage gradually increases to the selected voltage level, and the instrument records the insulation resistance value every second during the voltage ramp-up process. When there are defects in the insulation material, the resistance value decreases as the applied voltage rises and time increases. Conversely, when the insulation material is defect-free, the insulation resistance remains relatively constant during the voltage ramp-up process.

 

5.Step (STEP) Measurement:
The step test mode is also an automated testing process. Once the test begins, the output voltage gradually increases in steps of 10% of the selected voltage level, and the instrument records the insulation resistance value at each step. When there are defects in the insulation material, the resistance value decreases as the applied voltage increases. Conversely, when the insulation material is defect-free, the insulation resistance remains relatively constant during the voltage ramp-up process.

6.Dielectric Discharge Index (DD) Measurement:
The DD test is suitable for diagnosing multi-layer insulation. It involves measuring the discharge current value and the capacitance of the test object one minute after the test is completed to assess the condition of the multi-layer insulation. It is generally recommended to charge the insulation with 500V voltage for 30 minutes and then measure its capacitance and residual current after one minute. When setting the measurement mode, the DD calculation formula can be selected manually.

 

DD Value Judgment Criteria	＜2.0	2.0~4.0	4.0~7.0	＞7.0
Insulation Condition	Good	Caution Needed	Poor	Very Poor

 

ETCR3520 High Voltage Insulation Resistance Tester is a multifunctional high-end instrument capable of measuring various insulation performance indicators. Its performance characteristics are as follows:

1.5-inch touch screen, displaying test data simultaneously. Test operation and retri of historical records are very convenient.
2.Insulation resistance range: 0.005 MΩ to 30 TΩ.
3.Up to 8 levels of rated output voltage (50V, 250V, 500V, 1kV, 2.5kV, 5kV, 10kV, 15kV).
4.Maximum short-circuit current: 7mA.
5.High output power, strong anti-interference ability, stable testing capability even in scenarios with large distributed capacitance (such as long cable lines) and strong electromagnetic interference environments (such as substations).
6.Comprehensive measurement indicators: Insulation Resistance (IR), Polarization Index (PI), Dielectric Absorption Ratio (DAR), Step (STEP), Ramp (RAMP), Dielectric Discharge Index (DD), Capacitance (CAP), AC/DC Voltage (V).
7.Self-setting measurement mode, with options to choose PI, DAR, and DD calculation formulas, providing users with multiple choices.
8.Self-setting voltage mode: Users can freely set the test voltage and duration to accommodate special scenarios.
9.Voltage monitor: Automatically monitors the voltage of the object under test. Testing is automatically disabled if the voltage exceeds 36V, effectively protecting the instrument and operators.
10.Current monitor: Automatically displays the current of the test circuit.
11.Temperature monitor: Automatically displays the temperature and humidity inside the instrument box.
12.Automatic discharge function: After testing, the instrument automatically and rapidly releases the charge of the object under test without the need for an additional discharge circuit.
13.Large-capacity rechargeable lithium battery pack (14.8V 6400mAh) to ensure long-term testing work.
14.Large-capacity test record storage, with the ability to directly browse and analyze real-time test data with test date and timing information automatically stored for up to 1000 groups.
15.USB communication upload function, allowing recorded data to be uploaded to a computer for storage, data analysis, and statistics.
16.Bluetooth communication function, enabling the uploading of test results to a mobile phone.
17.Double-layer shell structure, rugged and durable, with IP65 protection rating (when the cover is closed).

Guangdong ETCR Electronic Technology CO.,Ltd. focuses on the research and production of electrical testing instruments and equipment, and is a manufacturer of high-voltage insulation resistance testers. For more information, please contact Guangdong ETCR Electronic Technology CO.,Ltd. service hotline: +(86-757)66860936, or visit the official website at www.etcr-instruments.com