What Is Megger Test and How Is It executed?

All about the megger test

The Megger test is a technique of testing making use of an insulation tester resistance meter that will help to confirm the condition of electrical insulation. Insulation fighting quality of an electrical system degrades with time, environment condition i.e., temperature, humidity, moisture and dust atoms. It also gets stuck negatively due to the presence of electrical and mechanical stress, so it’s become very necessary to check the IR (Insulation resistance) of equipment at a continuous regular interval to avoid any measure fatal or electrical shock.

In the electrical industry, there is no margin for error. Firm guidelines have been put into place to maintain the highest of standards, and more significantly the safety of personnel. Working in this field needs the best knowledge, the best personnel and the best accessible equipment. Having a Megger Test of your clearance means you are relying on the best.

 

Common types of the megger test

Battery Impedance Tester- Provides information about the health of lead-acid cells up to larger sizes and measures the most important functions for useability and endurance. Generally, measurements of batteries this size require taking the system offline, but with this unit, your devices can remain working and keep productivity at its maximum.

 

Cable Height Meters- checks the height of overhead cables to ensure their obedience with federal safety standards. They work by producing sound waves which reflect off of the cables and are picked up by the device. It also features a temperature sensor since the speed of sound waves can be changed by differing temperatures.

 

Ultrasonic Leak and Corona Tester- obtain ultrasonic sounds out of the air that cannot be notable by a human ear, turns it into a sound that registers on this machine and determines electronic corona and gas leaks. Gatherers pinpoint the exact location of the leak.

 

Phasing Detectors- Measure the estimated voltage of underground cables to ensure they are running at optimum capacity.

 

Insulation Testers- check to wire for insulation width, and also validates any damaged areas or compromise in the protective sleeve on the wire. Controls if there is a stress area that deserves attention.

 

Stages of the megger test

In-process testing

This is the most elementary process which can be done even on the readily installed equipment, so long as it is not running. This process includes the use of a meagering instrument to test the insulation integrity of the coils before it is associated with phases, neutral, and earth. In some cases, a multimeter can also be castoff. Inter-winding and winding-to-body resistances are checks at this stage. So, the dielectric withstanding voltage and insulation resistance of the coil can be resolute.

 

Ancillary Equipment Testing

This contains testing for insulation resistance and dielectric withstanding voltage for intersecting cables, high voltage bushings, busbars, and terminations. This can be directed when the components are interconnected or separated.

 

Generator Assembly Test

In this case, the generator is visually examined. Dusting is done and the machine's stability is also assessed. The pulse of the machine is carefully monitored using a special display instrument. The equipment is also meggered for lining resistance and dielectric withstanding voltage test.

 

How Megger Testing is Performed?

A multimeter is used as an insulation tester in some circumstances and mostly a continuity test only is performed. But for sensing and testing for a leakage current during a normal or overloaded condition, a special instrument known as the Insulation tester is used.

They quantity electrical leakage in wire and results are very dependable as we shall be passing an electric current through the device while we are testing. They confirm the electrical insulation level of any device such as motor, cable, generator winding, or general electrical installation. This is a very famous test being passed out since very long back. Not required it shows our exact area of an electrical puncture but shows the amount of leakage current and level of dampness within electrical equipment/winding/system.

 

The method of insulation resistance test or megger test are given below:

First, they will separate all the line and neutral terminals of the transformer. Megger leads are linked to LV and HV bushing studs to measure Insulation Resistance IR value in between the LV and HV windings.

Megger leads are associated with HV bushing studs and transformer tank earth point to quantity Insulation Resistance IR value in between the HV windings and earth.

Megger leads are associated with LV bushing studs and transformer tank earth point to quantity Insulation Resistance IR value in between the LV windings and earth.

 

Megger Safety Precautions

While using a megger, you could be injured or damage gear you are working on if the following MINIMUM safety protections are not observed.

 

Use megger on high-resistance measurements only, such as insulation measurements or to check two distinct conductors on a cable.

Never touch the test leads while the grip is being cranked.

De-energize and discharge the circuit totally before connecting a megger.

Disconnect the item being check from another circuitry, if possible, before using a megger.

 

Benefits of hiring Megger Testing Services

-Positive Equipment Condition Analysis

-Lower the Risk of Emergency Power System Failure

-Insured Obtainability

-Prognostic Repairs

-Helps Management

-Extrapolative Equipment Life Expectancy