How vital is insulation resistance testing? As more than 80% of electrical testing and maintenance includes analysis of insulation integrity, the response is “very significant”. Severe installation surrounding, significantly those with chemical contamination and temperature extremes leads to failure. This consequently reduces power reliability and personnel safety. Evidently, it’s significant to find out about such failures so that preventive measures could be taken timely.
Understanding the term “Insulation Resistance Testing”
Fundamentally, you’re putting in a voltage (particularly a stabilized and highly regulated DC voltage) beyond a dielectric, calculating the current quantity which flows via that dielectric, and then measuring (through Ohm’s law) a resistance computation. Let’s simply the term “current” more easily. This is about leakage current. Megohms are used to calculate resistance measurement. Further, to calculate insulation integrity.
Current flow via a dielectric may be observed as somewhat contrasting, but be sure, no electrical insulation is perfect. Hence, some current will always flow.
What are the objectives behind performing insulation resistance testing?
You can use insulation resistance testing for the following reasons:
- A troubleshooting tool.
- A regular interval preventive maintenance task.
- An installation demand to assist make sure challenges are met and to verify adequate hook-up.
- A quality control standard at the time a piece of the electrical device is designed.
Furthermore, by conducting insulation resistance testing, you can analyze if the electrical device is convenient to work with and you can find out the service life of the insulation almost. It must be conducted while repairing a new electrical device, hence whilst testing an electrical device, you can check whether insulation is convenient for the operation.
Insulation Resistance (IR) Test Principle Explained
It is to execute the voltage to calculate the steady-state leakage current and then divide the current by voltage (R= V/I). The IR test is successful when the IR encounters otherwise strike the significant value.
The targeted IR quantification can be measured by calculating the current flow of the target after the voltage “V” is applied and then, the “V” applied voltage can be segregated by the outcoming current “I”.
Working of Insulation Resistance Test
Commonly, you need to connect two leads (negative and positive) over an insulation hurdle. A third lead which often links with a guard terminal, can or cannot be present for the tester. The guard terminal functions as a shunt to unfasten the linked components from the quantification. Simply stated, it enables anyone to choose in analysing a few particular elements in a large piece of electrical device.
It’s a great option to know the item that needs to be tested. Fundamentally, you should be familiar with what is expected to be insulated from what. The device you’re testing will explain how you work and sustain a megohmmeter.
Once the connections are done, you can apply the test voltage for one minute. (It is considered to be a standard industry specification that enables us to make a relatively precise contrast of readings from past tests conducted by other technicians.)
Throughout this time, the reading of resistance must reduce or sustain relatively steadily. Larger insulation units indicate a gradual reduction; smaller units will persist steadily as the absorption and capacitive currents reduce to zero faster against a larger unit. You can read and record the value of resistance after one min.
The readings of resistance quantification also reform with time. This is so as electrical insulation elements indicate capacitance and will change throughout the test course. This is often frustrating to a beginner. As compared, it works as a powerful tool for a seasoned technician.
Benefits of Insulation Resistance Testing
- The IR testing is applied whenever you need to check the effectiveness of insulation whilst limiting the current flow
- It is a quality control standard utilized whenever electrical devices are produced.
- IR testing is significantly helpful in verifying the insulation quality.
- It is suggested to prevent electrical shocks.
Applications of Insulation Resistance Testing
- It is applied to determine the whole resistance between any two points segregated by electrical insulation.
- It is conducted to prevent hazardous events like electric shocks & short-circuits occurred once the insulation within electrical parts, elements, and devices is used in apartments, and industrial plants corrupts over a long time of use.
Safety Precautions before Conducting Insulation Resistance Testing
During IR testing, it is significant to perform some precautionary measures to confirm the worker’s safety. Let’s discuss some of the significant safety precautions mentioned below:
- Never conduct any insulation test on energized electrical wires or appliances. You need to be careful while conducting the test and hence, perform when it’s turned off.
- Stay away from touching or holding the test meter as much as you can.
- Disconnect all the linked switched and switch down equipment. Then, discharge the terminals only into the grounds.
- The three points testing technique is used to check if the circuit is dead. These points are to survey and test the present live circuit; then examine the chosen circuit and examine again the first live circuit to check if the IR meter is functioning properly.
- Protective equipment is significant when you are examining the live circuit. It is also significant when you are functioning in a possible inflammable surroundings.
- Utilize insulated gloves whilst connecting and examining the leads and switches for tests.
The Bottom Line
Insulation resistance testing is crucial to examine the insulation condition across an electrical wire or appliance. It has a significant role in incident prevention linked with electricity and examining quality control whilst electrical appliances are created. The reliability and quality of the IRF tester are very crucial to ensure the IR measurements are 100% reliable. To choose the finest IR tester, keep significant factors in account such as voltage requirements, place and industry type, and others. Finally, always remember the safety precautions before performing the IR testing.