If this is the first time for you then please read my previous post about Electric Earthing System. You will get enough idea for installing an earthing system for your home and industry.
In this post I am going to discuss about the Ungrounded and Grounded Neutral System and there Advantage and Disadvantage and I will also discuss about the preventive maintenance for earthing system. So let’s go.
Ungrounded and Grounded Neutral System:
Generally earthing of neutral point of the transformer and the generator is called the system earthing. Now, if the neutral point for any system is connected to the earth then it will be called grounded system.
But when the neutral for any system is not connected with the earth then it will be called ungrounded system. Connecting the neutral point to the earth through a resistance means resistance earthing and reactance earthing means connecting the neutral point to the earth through a resistance.
When the neutral point connected to the earth directly it will call solidly grounded.
Disadvantage of Ungrounded Neutral Earthing System:
- System Voltage Increase: When the earth fault occurs in line then for a healthy line voltage will increase three times if its ungrounded system.
- Protection Complicacy: In this system earth fault is not easy to sense and troubleshoot will become complicated.
- Arcing Ground: Sudden temporary fault can caused by failing of a branch creates an arc between the overload line and the ground. Arc extinguished and can restrict in a repeated regular manner. This is called arcing ground.
- Static Induced Voltage: Over voltage due to the static induced charges are not conducted to the earth.
Advantage of Grounded Neutral Earthing System:
- The System Voltage Will not Increase in Case of Ground Fault: When the healthy line of a grounded system i.e earthed the voltage of the healthy line will not increase w.r .t earth as in the case of ungrounded earthing system.
- Arcing Grounds are Eliminated: If the neutral point of the system is earthed then the distribute capacitive current from the lines to earth will neutralized by the current from the neutral point to earth and the arcing grounds will eliminated.
- It will be a stable neutral point.
- Life of the insulation will increase.
- Will get general safety to personnel and the equipments due to operation of the fuses.
- Over voltage due to sudden lightning will discharged to the earth.
- Earth fault relaying will relatively simple.
Preventive Maintenance for Earthing System:
- The earth resistance must need to be checked minimum two times in a year when it’s a dry season.
- Earthing system should checked periodically, when there is any kind of wear or loose connection with earth continuity conductor (ECC) or earthing lead or the earthing bus bar. Any types of looseness must be eliminated.
- It may need chemical treatment to the soil if the earth resistance is not sufficient or not desired level.
- It may need to pour sufficient water to the soil around the earth electrode through a funnel of earthing system pit periodically if the soil is very dry.
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