What is Megger or Insulation Tester?
Insulation tester or so-called megger helps us to measure the resistance between insulators, which should usually be high resistance. These devices can measure very high resistances by applying a constant and very high voltage to the insulation under test and measuring the current flowing through the equipment. Insulation testing device can be used to test vacuum switches, high voltage power distribution networks and test devices used for insulation in many applications due to their lightness and portability.
Migraine or insulation tester (Insulation tester) is a tool for measuring very high resistances. Usually includes a resistance of about 5000 megohms. Such as cable insulation control when connected to ground and insulation resistance of power cables.
In fact, these very high resistances are the insulation resistance of cables and the like. To measure these very high resistances, a lot of voltage is required. Insulation testers are used to evaluate the quality of insulation at high voltages. In some devices, the voltage is about 10 kV. Usually the voltage of the migraines is between 100 and 10 kV.
The voltage source required by the device is usually alternating and it is generated in two ways. In the first method, using a Dc power supply, the Dc voltage is converted to Ac by means of an oscillator (oscillator) and then, by means of a transformer, the alternating voltage of the oscillator output is increased to any desired value. In the second method, by means of a generator The simplest actuator is the AC voltage.
Measurement of insulation of cables, especially underground cables, which due to the infiltration of water over time by reducing the insulation resistance between the wires cause leakage current and voltage drop in (Insulation testers) are of particular importance in the early generation, A manual generator was used to generate the required voltage, but now the new problems have been solved with a new generation of migraines (insulation testers).
Ability to determine the required voltage from 50 volts to 20 kV, 50 tera ohm resistance, possibility of timing to determine the required test time, possibility of combined timing to determine two different types of voltage in two continuous times for advanced tests, with DC output Also, connection to a computer is a feature that is included in these devices. In some models, it is possible to store information in the form of a data logger to record the amount of applied voltage and changes in cable resistance at different times.
Types of applications and advantages of Megger (insulation tester):
1) Measurement of resistance of motor windings
2) Measurement of resistance of cables and other insulating materials
• Testing of electrical switches in about megaham
• Measurement of resistance between each phase and ground
• Testing of vacuum switches
• High voltage power distribution networks
• Testing of devices used for insulation
• Factories producing single-phase and three-phase electric motors
• Factories producing wires and cables
to use megger(Insulation testers) The following must be observed:
Danger: Do not use voltages of 1000 VDC and 750 VAC.
– Do not use the device around environments where gas leaks, explosives, combustion gases, humid or dusty
environments – Never use in humid environments.
– When using test jacks, be careful with your fingers so that they do not connect to the metal part.
– Never use the device without insulating covers.
Before testing, make sure there is no current in the circuit.
– Do not use the device when it is not working properly or when the insulation on the connection wires of the device is lost.
– Be very careful when working with voltages 30 V rms, 42 AC 42 and 60 V DC because the possibility of electric shock is high.
– After testing the insulation, be sure to discharge the electrical charge of the circuit.
– Do not replace the device battery while in a humid environment.
– Make sure that the connection pins to the device are firmly in place.
When measuring the insulation resistance, remove all power sources from the circuit and discharge the electric charge.
– Do not use the device when the battery icon appears on the screen.
– When not using the device for a long time, remove the battery.
– Do not expose the device to high temperatures, humidity, explosive, usable environments, and environments with high magnetic fields.
For voltage size Insulation tester (Meger) Do the following steps:
1- First select the type of AC or DC voltage by pressing the appropriate key.
2- Connect the red wire to the V part and the other wire to the Com terminal and connect the interface wires to the lizard jacks.
3. When the red negative voltage wire is connected, a negative sign (-) appears on the display.
Disconnect the connections between the test props and the circuit under test when the voltage measurement is complete.
Measurable quantities in (Insulation testers):
1) AC / DC voltage measurement
2) Insulation resistance measurement
How to work with Megger:
Exactly the same as a standard resistance measure, except that in the manual type, it is rotated by a handle on the armpit, so that the generator rotates, resulting in a voltage that is increased by incremental transformers. It is then converted to direct voltage (dc) by rectifiers and used.
How to tell if you are healthy:
We turn the handle that is on the armpit and connect the two ends of the wires together, if the hand is set to zero, it is not safe. To test the ohmmeter, we connect the two ends of the props and place the range on the ohm. The hand must be deflected, in which case it is healthy.
Rose Calibration Company in Melbourne, Australia with over ten years of experience provides all calibration, maintenance, and repair services throughout Australia. If you live in Sydney, Melbourne, Adelaide, Perth, Geelong, and Brisbane, you can receive your quote in less than two hours by fill-up the form via the “Booking” link.