Insulation resistance test In order to measure the total electrical resistance of insulation of a product or equipment. Doing this test is usually done as a quick check after manufacturing, installing or repairing a product. It is also a useful test to perform during preventive maintenance over a long period of time. Changes in insulation resistance measurement can help predict (repair or replace)
Introducing a device for measuring or testing insulation resistance
Measurement or testing of insulation resistance by a device called Megger (Megger) is a device that is more than 100 years old and is used to measure a lot of insulation resistance. The method of operation of this device is similar to ohmmeter, except that instead of a few volts, a few kilovolts It is applied on the tested part and with a range of 1 to 10 kV Dc, it can be used and available as needed, and based on this, it is able to show much higher resistances (Giga ohms) with better accuracy.
Principles of operation of the device
This device generates its test voltage by converting 12 volts (internal battery of the device) to a minimum of 1 and a maximum of 10 kV Dc.
This voltage is controlled quickly by current control circuits so that as soon as the current increases from the allowable limit or a short circuit speed, the desired voltage decreases to a reliable level. This is to protect the internal systems as well as the components being tested.
Note: Older devices were charged by hand and the device also needed to be discharged, but new devices are charged with an internal battery and are discharged automatically after the test.
Applications and capabilities of Miger
Measurement of total insulation resistance in electrical panels, types of electrical equipment, types of transformers, motors and cables
For rapid testing and evaluation of a product after production, installation or need for repair, as well as equipment that has passed its useful life, in which case by showing a change in the amount of insulation resistance to prevent errors.
Increase the useful life of electrical equipment
Articulation tests and overhead cables
Possibility of inspection and supervisory tests when delivering and receiving goods from the equipment warehouse
Instructions for determining the amount of voltage injection of insulation resistance test by the device Megger In weak pressure boards
In low pressure panels, by applying a voltage of 1 kv Dc to the main circuit by the Migr device in a period of 1 minute, which of course does not record the time using devices with new technology, this is the device that intelligently calculates the appropriate time to resist Automatically calculates and indicates according to the new standard IEC 61439 the amount of insulation resistance for each circuit should be at least V / Ω1000 and experimentally should be more than 5 Mohme
In addition, this test should be performed between phase, zero and earth lines in 5 connection modes as follows.
- L1 with L2, L3, N, PE
- L2 with L1, L3, N, PE
- L3 with L1, L2, N, PE
- N with L1, L2, L3, PE
- PE with L1, L2, L3, N
What is a dielectric test? (or (Power Frequency Dielectric Withstand Test (HiPot)))
Dielectric test is used to check the correctness and continuity of insulation of electrical equipment. This test is also known as power insulation test of power frequency (HiPot), which stands for High Potential or high voltage. Used each other in industry.
To evaluate the electrical endurance of equipment, they are tested at power frequency voltage for 1 minute. The test voltage is expected to be at a higher level than the working voltage, so that it can simulate possible stresses during the years of service of the device. Indoor installations, tests are performed only in dry conditions. External equipment is tested in the standard rain conditions described in the relevant standards, if necessary.