NGR full form is the Neutral Grounding Resistor, which is used in the electrical system to protect the transformer and generator. As the name suggests, the neutral ground resistor connects the neutral point of a transformer or generator to the ground.
After knowing the full form of NGR, let us discuss some points related to neutral ground resistors.
What Is NGR in Electrical?
A Neutral Ground Resistor(NGR) is made using materials such as Stainless Steel and Nickel Chromium Alloy (NiCr). These materials have a stable resistance that does not change with temperature. Porcelain and ceramic are used to support the resistor elements.
Purpose of NGR (Neutral Ground Resistor)
The primary purpose of an NGR (neutral ground resistor) is to limit the ground fault current that can flow in the event of a fault in the system. This helps prevent excessive currents and associated damage to equipment during a ground fault.
What Is the NGR Panel?
The NGR panel is an outdoor enclosure that houses a neutral grounding resistor, current transformer, CT shorting terminals, insulators, terminals, and bus bar.
Installation of NGR in Transformer and Generator
Neutral ground resistors are connected between the neutral point of a transformer or generator and the ground. The resistor is usually sized and rated based on the equipment’s voltage and its full load current.
The image below shows how to install NGR for transformer protection.
The image below shows how to install NGR for generator protection.
Resistance Value of NGR
To calculate the NGR resistance value, we need two parameters – the rated voltage and current of the equipment. Let’s assume that the line voltage of the transformer is VL, and its full load current is IF. The resistance value can be calculated using the following mathematical formula.
Advantages and Disadvantages of NGR
Advantages
- Protects equipment from high ground fault currents.
- Reduces insulation stress and minimizes equipment damage.
- Allows selective tripping of faulty circuits.
- Improves safety and reliability of the power system.
Disadvantages
- Generates heat and energy loss during faults.
- Requires extra space for installation.
- Not suitable for very high-voltage systems.
- Needs regular monitoring to ensure proper functioning.
NGR Monitoring and Protection
The NGR (Neutral Ground Resistance) plays a vital role in the protection of transformers and generators. It is essential to ensure that the NGR is healthy at all times. To monitor the condition of the NGR circuit, a neutral ground resistance monitoring relay is utilized, which provides a signal indicating any faults or issues with the NGR circuit.
This is all about the full form of NGR and its application in electrical circuits.
Conclusion
The NGR full form in electrical is Neutral Grounding Resistor, and it is one of the most important components for the safe operation of transformers and generators. By connecting the neutral point to the ground through resistance,
NGR limits fault currents, reducing equipment damage, and improving system stability. The NGR panel, resistance value, and monitoring system further ensure reliable protection and easy fault detection.
In short, understanding the NGR full form in electrical along with its purpose, installation, advantages, and applications is essential for every electrical engineer and power system professional.
FAQs on NGR Full Form in Electrical
The full form of NGR in electrical is Neutral Grounding Resistor.
The purpose of NGR is to limit ground fault current and protect electrical equipment like transformers and generators from damage.
An NGR panel is an outdoor enclosure that houses a neutral grounding resistor, current transformer, insulators, bus bar, and terminals.
The resistance value of NGR is calculated using the equipment’s rated voltage and current with the formula:
R=V/I
NGR is installed between the neutral point of a transformer or generator and the ground.
NGR monitoring is done using a neutral ground resistance monitoring relay that checks the health of the NGR circuit and signals any faults.
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