How to select the best insulation resistance tester?

To detect current leakage and poor or damaged insulation that may cause arc faults, blown circuits, and danger of electrical shock or fire, an insulation resistance tester applies a high voltage, low current DC charge to wires and motor windings to measure their resistance.

What is insulation resistance testing?
The definition of the insulation resistance test is the test that is used to measure the total resistance between any two points that are separated by electrical insulation. This test may be defined as the test that is used to measure the resistance between any two sites. The name “megger test” has also been given to this examination.
Therefore, the purpose of this test is to measure the effectiveness of the dielectric or insulation in limiting the passage of electric current. Therefore, the infrared (IR) tests are not only highly useful in confirming the insulation quality while the product is being created, but they are also very helpful in verifying the insulation quality when the product is being used over time.

Why is an Insulation Resistance Test Required?
It is necessary for an electric current to pass through a conducting wire in order for it to arrive at its destination, yet some energy is lost during this process. We must inspect the insulation to see whether there is any leakage taking place.
This is because stray currents might represent a significant risk. These tests must be carried out so that nobody gets hurt.
This test is required to guarantee the reliability of electrical appliances and assure their safety. Using this test, one may assess whether the electrical equipment is in great operating condition, and one can also predict how long the insulation will be effective.
It is crucial to test insulation anytime new electrical equipment is being repaired or installed. This is because testing insulation ensures it is in great operating condition.

How to select the finest insulation resistance tester
When choosing the best insulation resistance tester, there are six factors that it should take into consideration, including the following:

What equipment needs testing?
In the first phase, you’ll list all the typical machines that unavoidably need insulating resistance tests. Document the yearly target number of insulation resistance tests and the nominal voltage rating of the equipment (located on the nameplate). Indicating the test voltage required from the insulation resistance tester WB2681A, the nominal voltage is a useful starting point.
The expected number of yearly insulating resistance tests may come as a surprise. As the number of tests that need to be run increases, so does the significance of the test instrument’s general quality, durability, and convenience features.

What are the voltage requirements?
The manufacturer’s suggested dc insulation resistance test voltage should be used to determine the output test voltage applied to the device. Standard industry values should be used instead in the absence of a defined test voltage.
The output test voltage required must be supplied by the insulation resistance tester you choose. There is a wide range of insulation resistance testers on the market, some of which can only provide a test voltage of up to 1,000 V dc, while others can provide 5,000 V dc or more.

Where are the tests need to be conducted?
Selecting optional features for an insulation resistance tester might be aided by thinking about both the testing environment and other potential applications for the tool. If, for instance, a single device can do both digital multimeter duties and insulation resistance testing, that’s a big-time saver.
It is inconvenient to lug about a digital multimeter for voltage testing and the insulation resistance tester since it is necessary to ensure that all circuits and equipment are de-energized before connecting the tester.
These are some questions to consider while planning a test environment:
1) If you’re using an insulating resistance tester, ask yourself, “Will it be utilized for troubleshooting, preventative maintenance, or both?”
2) “Will the testing equipment be utilized only in a factory, or will it also be used in a shop?”
Different insulation resistance tests come in varying sizes and portability.

What you understand from an insulation resistance test
Insulation resistance testing assigns a numerical value to the state of the conductor insulation and the internal insulation of various pieces of electrical equipment to provide a qualitative assessment of their overall condition.
Applying a dc voltage to the wire or equipment being tested is the first step in performing an insulation resistance test. A small number of current escapes from the testing apparatus and enters the conductor, where it starts to charge the insulation.
Capacitive charging current is the name given to this current, and it may be seen on the front of the meter.
When the charging current starts to build up, the reading on the front of the meter will reflect a low number for the measured resistance. Imagine this as electrons begin to flow into the insulation and become stored there.
It will reduce the megohm value in proportion to the amount of current drawn from the test set. If the insulation is of excellent quality, it will soon get charged, and the meter reading will begin to stabilize at a higher megohm value.
The absorption current, also known as the polarization current, is the subsequent current that flows. The level of contamination in the insulation is directly proportional to the quantity of electricity absorbed.
For instance, if moisture is present in the insulation, the absorption current will be greater, suggesting that the value of the insulation’s resistance is lower. However, it is important to remember that accumulating this absorption current requires more time than the capacitive charging current.
Because of this, an insulation resistance tester WB2681A that is run for too short of a time will observe the capacitive charging current and will not begin to exhibit signs of impurities in the insulation.
In conclusion, the current known as the leakage current is the one that flows through the insulation that has been damaged and into metal components that do not carry current. In most cases, this current is taken into consideration during an insulation resistance test.
However, it must also include the absorption or polarization current to achieve more precise maintenance and troubleshooting.
LISUN provides the best testers according to your requirements.

Will you measure polarization current?
The insulation resistance tester needs more time to operate because of the increased time required for the polarization current to build up. This evaluation typically takes five minutes. Take a reading from the insulation resistance tester after one minute and again after ten minutes to get an idea of the level of contamination and general insulation condition.
To get the polarization index, take the reading from the first minute and divide it by the reading from the tenth minute. It is recommended to keep track of both the spot reading test results and the polarization index values as part of a regular maintenance schedule. It should always compare the most up-to-date values to the historical average. Never have a polarization index value under 1.0.

Will you measure the leakage current?
Those testers that automatically get this data should be prioritized for use in industrial settings. However, all insulation resistance testers will show leakage current and offer the information to estimate insulation contamination.
During leakage testing, the test voltage is applied to the component for one minute before a resistance measurement is taken to determine the amount of leakage current. The spot reading test refers to this specific kind of examination.
The spot reading test is the gold standard for determining leakage current through insulation because it enables capacitive charging currents to settle. The spot reading test should serve as the basis for establishing minimum insulation resistance values in megohms.

What is your experience level?
There is a direct correlation between the skill and expertise of the individual operating the testing device and the accuracy of the results obtained. Think about the experience level of the people conducting the insulation resistance testing before making a purchase.
If the requirements for the program are low and the user base is similarly inexperienced, it makes sense to prioritize simplicity and a stripped-down set of features. It may do testing for insulation resistance with little training. There are enough resources for this purpose, such as instruction manuals and introductory literature.
It should consider on-the-job training in the correct and safe use of insulation resistance testers for novice workers. Make the insulation resistance tester’s output test voltage and other features suitable for the intended use. Instruct people conducting the exams on how to do so effectively.

What does safety have to do with testing and fixing problems??
The priority of testing and troubleshooting should always be protecting everyone involved. It must never connect the insulation resistance tester WB2681A to a live circuit because it generates high dc voltages.
The tester’s output is also dangerous enough to fry electronic components. Never plug an insulation resistance tester into a battery charger, PLC, VSD, UPS, or other solid-state electronic equipment. Certain insulation resistance testers may flash or beep as a safety feature if the voltage is detected on a circuit.
After an insulation resistance test has been completed, the insulation may continue to contain a considerable voltage charge. After a test is complete, the insulation will be discharged automatically by most testers but not all.
When deciding on an insulating resistance tester, this is a crucial factor. It may show insulation resistance and voltage levels on certain models of testers. After turning off the test output voltage, the voltage may be seen on such testers as it gradually decreases to zero.
Depending on the manufacturer, the insulation resistance tester may need to stay attached to the circuit or component being tested for up to four times as long after the test as was performed to guarantee a safe discharge.
After a test is complete, most technicians will ground the circuit to ensure the insulation has been discharged. When shopping for an insulation resistance tester, it is important to consider whether it has a self-discharge function.

The next thing to do when choosing an insulation resistance tester is
Using the right insulation resistance tester allows for fast and accurate troubleshooting and thorough documentation of service history.
You should make a list of the machines that need to have their insulation resistance tested, as well as the test voltages that will be required for the devices and insulation, the testing environment, any special features that will be necessary, the technicians’ levels of experience, and the safety features of the testing machinery.
However, technicians may only benefit from using an insulation resistance tester if they have access to one suitable for the task.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

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