A megger meter is an electrical measuring instrument designed to measure large resistance values. When measuring resistance, a relatively high voltage is applied to the measured circuit (in most models – 100, 500, 1000 or 2500 volts ). Its value may be unacceptably enormous. Gradually, however, rather quickly, the properties of the insulation coating can deteriorate significantly. Moreover, any additional external impact, for example, mechanical, can violate the integrity of the weakened insulation.
Further, there is a high probability of a short circuit at the damage site and its ignition due to high temperature in the short circuit zone. Therefore, it is necessary to periodically check the state of insulation using a megger insulation tester for the magnitude of the leakage currents in it to prevent the destructive consequences of its degradation.
In most cases, you can check the insulation status using a megger insulation tester. This is a specialized device that is made specifically for this. When it is used, an electric circuit is created in which an imaginary resistor is included, numerically equal to the value of the insulation resistance at the measurement site.
The meter measurement results make it possible to determine the parameters of the state of the insulating coating, according to which coefficient calculations are made to assess the prospects for further use of the tested wires and cables.
Purpose of measurements
The datasheet contains information on the insulation resistance of wires and cables. Therefore, with its regular monitoring, it is possible to detect changes that occur with it under existing operating conditions. The data obtained from the control results can prevent such events as an electric shock when in contact with a wire or cable, overheating or ignition of a wire or cable.
The insulation test is carried out under certain conditions. So, experienced specialists know that it is imperative to check the temperature and humidity of the air. The air should be warmed up to 25 degrees, but deviations within 10 degrees are also acceptable. Humidity should not exceed 80 percent.
Using a megger meter is not destructive.
When insulation has been damaged, a megger tester is used in determining the cause by testing. The test is typically conducted at rates that are low as compared to the insulation. The insulation tests may range from as low as 40 V dc to 10 kV. A 10 kV diagnostic insulation resistance tester – Megger is used to ensure that the insulation is not compromised. This is because, when a voltage is used, which does not match with the testing, it can cause degradation of the insulation material. Thus, it is very vital to select an insulation tester megger that matches the rating of material it will be testing.
The main advantage of using a megger meter is that it ensures the safety of the equipment being tested without damaging it. This can be ensured by setting the megger properly with the right voltage, which will be used to test the equipment. It can’t destroy the material being tested.