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General Discussion & Feedback => Just Chat! => Topic started by: NTYNUT on 17/08/2018 09:58:42

Title: What is megger test
Post by: NTYNUT on 17/08/2018 09:58:42

Hello
What is megger test

Title: Re: What is megger test
Post by: evan_au on 17/08/2018 10:30:29

"Megger" is an abbreviation of MegOhm meter, ie a device for measuring insulation resistance, in the MegOhms range.

For electrical safety, users must be insulated from dangerous voltages, where voltages > 32VAC are considered potentially dangerous. (Old-fashioned telephone lines deliver >32VAC while the phone is ringing, but they get around the safety issue by pulsing the ringer, which provides a regular interval where you can pull away from this AC voltage.)

To test a power cord which normally operates at 230VAC, standards call for testing the insulation at around 2500V. This is to account for voltage surges that can occur on the power lines, and also provides for some degradation in the insulation over time.

The MegOhm test applies a high voltage, and measures the current which flows, giving a display calibrated in MegOhms.
See: https://en.wikipedia.org/wiki/Megohmmeter

Title: Re: What is megger test
Post by: NTYNUT on 17/08/2018 10:36:18

Quote

"Megger" is an abbreviation of MegOhm meter, ie a device for measuring insulation resistance, in the MegOhms range.

Hello
Why we measure insulation resistance

Title: Re: What is megger test
Post by: evan_au on 18/08/2018 12:47:38

Quote from: NTYNUT

Why do we measure insulation resistance?

If the electrical insulation does not have sufficient resistance:
- Humans may be harmed by coming into contact with dangerous voltages
- High voltages may leak into computer equipment, damaging it
- Lightning surges can cause the insulation to fail
- Current can flow through the insulation, heating and weakening it. Eventually, the wires touch (maybe starting a fire), the generator gets overloaded, and the intended load receives no power
- This can happen if water gets into equipment; water can conduct electricity, if it has some chemical compounds dissolved in it.

Poor quality insulation is bad for everyone using electricity.
See: https://en.wikipedia.org/wiki/Insulator_(electricity)#Breakdown

Title: Re: What is megger test
Post by: NTYNUT on 18/08/2018 12:50:16

Quote

If the electrical insulation does not have sufficient resistance:
- Humans may be harmed by coming into contact with dangerous voltages
- High voltages may leak into computer equipment, damaging it
- Lightning surges can cause the insulation to fail
- Current can flow through the insulation, heating and weakening it. Eventually, the wires touch (maybe starting a fire), the generator gets overloaded, and the intended load receives no power
- This can happen if water gets into equipment; water can conduct electricity, if it has some chemical compounds dissolved in it.

Poor quality insulation is bad for everyone using electricity.

Hello
what does insulation do i am not getting it

Title: Re: What is megger test
Post by: Bored chemist on 18/08/2018 12:59:46

Why don't you search for this sort of thing yourself, rather than asking us to do it for you?

https://en.wikipedia.org/wiki/Insulator_(electricity)