What is an insulation resistance tester?

Feb 15, 2022 Detection of photovoltaic modules

What is an insulation resistance tester?

Insulation resistance tester, also known as high-voltage insulation resistance tester, withstand voltage insulation tester, is mainly used to measure the insulation resistance of electrical equipment and insulating materials. The safety performance test of photovoltaic modules and electrical equipment of photovoltaic power plants is very important, which is related to the possible electric shock problems that people may have when installing photovoltaic modules or related electrical equipment. At present, various standards, such as UL1703, IEC-61730-2, IEC-61215, etc., require manufacturers to use “voltage insulation testers” for safety testing when designing and producing electronic or electrical products. The so-called withstand voltage insulation test is actually a voltage higher than the normal working voltage to be tested on the product, and this voltage must last for a period of time. If an electrical device is within the specified time. If its leakage current is also kept within the specified range, it can be determined that the electrical equipment works under normal conditions and is very safe. The insulation resistance test mainly measures whether the insulation between the current-carrying part in the module and the frame or the outside of the module is good. Usually, a large constant voltage (DC 500V or 1000V) is applied and maintained for a specified period of time. standard. If the resistance value remains within the specified range within the specified time, it can be determined that it operates under normal conditions, and the product should be relatively safe. The higher the insulation resistance value, the better the insulation of the product. The insulation resistance value measured by the insulation resistance test is the equivalent resistance value formed by the associated networks between the two test points and their surrounding areas. However, the insulation test cannot detect the following conditions: the dielectric strength of the insulating material is too weak; there are pinholes in the insulator; the distance between parts is not enough; the insulator is broken by being squeezed. The above conditions can only be detected by the withstand voltage test.

Here we take the PVCHECK product of HT Company as an example. The characteristics of its products are as follows:
(l) Safety inspection.

(2) Continuity test of protective conductor (LOWΩ).
Comply with the standard IEC/EN62446, the test current is greater than 200mA.

(3) Measurement of insulation resistance (MQ) of photovoltaic modules/strings (test can be carried out with electricity), as shown in Figure 1.
①Comply with the standard IEC/EN62446, the test voltage is 250V, 500V, 1000VDC.
②3 measurement modes: Field, Timer, String.
③Insulation test of frame and metal structure.

What is an insulation resistance tester?
Figure 1 PVCHECK products can be charged to test insulation resistance

(4) PV photovoltaic system efficiency evaluation (EFF).
①Measure the DC voltage, DC current and DC power output of PV modules/strings.
②Measure irradiance (W/m²) through a reference unit connected to the optional remote unit SOLAR-02.
③Measure the module and ambient temperature by connecting to the optional remote unit SOLAR-02.
④Apply to the relationship of compensation DC efficiency.
⑤ Instantly assess DC efficiency against user-set limits.
⑥Programmable IP parameter record of photovoltaic power generation system 5a to 60min.

(5) Quick check (IVCK) in line with standard EC/EN62446
①Measure the open-circuit voltage Uac of PV modules/strings up to 1000VDC.
②Measure the short-circuit current lc of photovoltaic modules/strings up to 10A.
③ Measure the illumination device in an optional reference unit.
④ Directly assess the test results (OK/NO).
⑤Connect the optional remote unit SOLAR-02.
⑥ Internal database of up to 30 photovoltaic modules can be customized.
⑦ Display results in OPC and STC.