Can you use a digital multimeter to measure the insulation resistance of the motor coil to the shell?

According to the requirements of national standards, this kind of insulation resistance needs to be tested with a special insulation tester.

The importance of security testing ... the safety of users

In today's world with high consumer awareness, every manufacturer of electrical and electronic products must do its best to ensure the safety of products. Every product should be designed as well as possible to prevent users from getting an electric shock. Even if the user makes a mistake, there should be no chance of getting an electric shock. In order to meet recognized safety requirements, "withstand voltage tester" must be used. Safety enforcement agencies such as UL, CSA, IEC, BSI, VDE, TUV and JSI require manufacturers to use withstand voltage tester as a safety test when designing and producing electronic or electrical products. These safety execution units sometimes need to test insulation resistance, grounding resistance and even leakage current of some products.

Dielectric withstand voltage test

The basic theory of withstand voltage test is to expose a product to a very harsh environment. If the product can maintain its normal state in this harsh environment, it can be sure that it works in the normal environment and it will certainly maintain its normal state. The most commonly used conditions for withstand voltage test are:

Functional testing during design ... to determine the conditions under which the designed product can meet its functional requirements.

Specification testing in the production process ... to confirm that the products produced meet the standards required by its specifications.

Confirmation test during quality assurance ... to confirm that the product quality meets the safety standards.

Safety test after maintenance ... confirm that the repaired product can maintain safety standards.

Different products have different technical specifications. Basically, in the withstand voltage test, a voltage higher than normal operation is applied to the product for testing, and the voltage must last for a specified time. If the leakage current of a component is kept within the specified range within the specified time, it can be determined that the component works under normal conditions and should be very safe. Excellent design and good selection of insulating materials can protect users from accidental electric shock.

The withstand voltage test made by this instrument is generally called "high voltage dielectric test" or "withstand voltage test" for short. The basic rule is to use twice the working voltage of the tested object plus 1000 volts as the test voltage standard. The test voltage of some products may be higher than 2 X working voltage+1000 v.

For example, the working voltage range of some products is 100V to 240V, and the test voltage of such products may be between 1000V to 4000V or higher. Generally speaking, the test voltage of products with "double insulation" design may be higher than the standard of twice the working voltage+1000 V.

The output voltage of withstand voltage tester must be kept within the range of 100% to 120% of the specified voltage. The output frequency of AC withstand voltage tester must be kept between 40 and 70 Hz, and its peak value should not be lower than 1.3 times root mean square (RMS) voltage, and its peak value should not be higher than 1.5 times RMS voltage.

Insulation resistance test (insulation resistance test)

Some newly designed safety testers mostly cover the function of insulation resistance test. Basically, the insulation resistance test function must provide a voltage of 500 to 1000VDC, and the resistance measurement range must be from several hundred KW to several GW. These functions can enable the manufacturers of products to meet the safety requirements. In some specific products, TUV, VDE and other safety law enforcement units will require insulation resistance test before the withstand voltage test. At present, this requirement is mostly cited in the safety regulations test in product design.

The basic theory of insulation resistance test is very similar to withstand voltage test, which is based on leakage current, while insulation resistance test is based on the form of resistance value, which must usually be greater than MW.

The higher the insulation resistance, the better the insulation performance of the product. The connection mode of insulation resistance test is exactly the same as that of withstand voltage test, and the measured insulation resistance value is the equivalent resistance value formed by various related networks connected between two tested objects and their periphery.

The cover insulation resistance test function included in Qingdao Ousheng electronic safety test equipment is an independent test function, which will not overlap with the withstand voltage test function and is more convenient to use.

Product name: insulation resistance tester

Product model: 960 1