Q:

How is a Megger tester used?

A:

An insulation resistance tester (commonly called a Megger after a prominent company that manufactures them) is operated by hooking it up to a piece of electrical equipment and running voltage across the insulation on the equipment. The Megger calculates how well the electrical insulation on the equipment is working by checking how much current is flowing between the Megger to the machine. The higher the resistance, the less current will flow, amounting to better electrical insulation shielding. This is important, because poor insulation leads to equipment breaking down.

To test for insulation resistance, make sure to isolate the equipment from any other sources of current. Turn off the equipment, and disconnect it from other components. If it is not possible to completely isolate the equipment, observe what other conducting parts it is connected to, such as cables or wires, and be aware that the insulation resistance rating will be lower than due to these other components. Ground and discharge the equipment to prevent sparks or electrocution both before and after testing.

Attach two leads from the Megger across the equipment's insulation, with one lead on one side and one on the opposite side, and run the voltage on the Megger for at least one minute. The device will calculate the resistance using Ohm's Law and give the resistance rating in megaOhms.

Learn More

Related Questions

  • Q:

    Why is electrical grounding important?

    A:

    Electrical grounding reduces the risk of severe electrical shock from uninsulated metal components inside of electrical devices, appliances and power tools. When a grounded system is secured properly, the leaking current, known as the fault current, is transferred harmlessly. This type of grounding is common in the manufacturing industry and prevents hazardous static charges from accumulating.

    Full Answer >
    Filed Under:
  • Q:

    What is the difference between metal clad cable and armored cable?

    A:

    According to Radioshack, the difference between metal clad cables and armored cables is that armored cables are used for higher electrical draw installations, while metal clad cables are used for lower current loads. They differ in wire gauge, resistance, grounding, installation and limitations.

    Full Answer >
    Filed Under:
  • Q:

    How can I pull wire through a conduit?

    A:

    To pull wire through an electrical conduit with an existing pull wire, make a loop in the pull wire, attach the new wire, and have an assistant pull the wires while you lubricate them. The supplies you need are a wire spool, tape, lubricant and a cable puller.

    Full Answer >
    Filed Under:
  • Q:

    What causes a power transformer to hum?

    A:

    Sheets of magnetic steel in the transformer vibrate in a magnetic field, generating an audible hum. Transformers operate by changing an electric current with one voltage and current value to a magnetic field, which is then transformed back into an electric current with a different voltage and current value.

    Full Answer >
    Filed Under:

Explore