How To Reduce Voltage Between Neutral and Earth?

The neutral-to-earth voltage occurs when the electric current passes through a neutral conductor, the neutral-to-earth voltage is also known as stray voltage. When the voltage exceeds a certain threshold, the system will be shorted, which means excessive voltage.

Shorted systems have harmful consequences like electrocutions, electrical burns, and fires; therefore, you need to lower or reduce the voltage between neutral and earth. This way, you will avoid any harmful consequences.

How To Reduce Voltage Between Neutral and Earth?

The high voltage between neutral and earth can be due to many reasons; therefore, you need to determine the leading cause for the high voltage and then imply a suitable solution. The solutions can vary from having an excellent grounding system to lowering the current passing through the neutral. 

Solutions to Reduce the Voltage Between the Neutral and Earth (Single Phase)

The reason you have an excessive or high voltage between neutral and earth must first be determined to imply a suitable solution. There are many solutions to reduce the high voltage between the neutral and the earth, like installing a transformer for insulation or modifying the wire between the neutral and earth.

Great Grounding System

The ground’s resistance can be one of the reasons for excessive voltage between the neutral and earth. The current passing through the wire can produce a high voltage if the resistance of the ground is increased. Therefore, you need to make sure you have that you have a great grounding system.

Great ground systems ensure that the resistance of the ground is small as possible; you can check if you have a good ground system by checking the wires. The length of cables in the system can affect the resistance of the ground, as any unnecessary increase in the wire’s length will increase the resistance.

To determine the exact required length of the wire, you will need to determine the system’s safety requirements and maximum electricity consumption first. The last step is determining the needed diameter of each ground wire on different floors.

Lowering the Current in the Earth Wire

You can lower the current in the earth wire by several steps; first, you will need to improve and strengthen the insulation between phase lines. Next, prevent forming of any loop in the earth’s wire by checking the equipment for any current leakage. The last step is to get rid of the hybrid junction of the earth and the neutral wire.

Remember that it’s impossible to find the ground wire iterative earthing at different ground potentials. Therefore, even if you try to use a non-contact voltage tester, it won’t be easy to locate each iterative earthing. Consequently, you need to insulate each earth wire from the ground and connect them to a single point in high-flow DC areas.

Adding a Transformer for Insulation

Adding a transformer for insulation is a great way to reduce the voltage between neutral and earth. The transformer ensures the load operation when the voltage between the neutral and the earth is excessive and guarantees a normal startup; meanwhile, other methods can not control it.

Adding a transformer for insulation will isolate the connection between the output and the input; however, you can only use this method for UPSs without an isolation transformer. So, when you add the transformer to the output end, the voltage between the neutral and earth will be reduced.

When used, this solution has a significant advantage: it effectively solves the issue of the neutral-earth voltage at the load end. This is due to the isolation of the neutral wire earthing makes the wire meet the different power requirements.

Modifying the Wire

Any wire’s length and cross-sectional area affect its resistance; therefore, you can modify the wire between the neutral and the earth by lowering its length or increasing its cross-sectional area to reduce its resistance. When the resistance of the wire decreases, it will result in a lower voltage between the neutral and earth.

The neutral wire in AC systems carries current, as it’s used to maintain the current back, so the circuit is complete. Therefore, when you lower its resistance either by increasing its cross-sectional area or decreasing its length. As a result, the voltage resulting from passing the current through it will be reduced, which means a lower neutral-to-earth voltage.

Increase the Distance between Conductors

When current passes through a wire, it generates an electromagnetic field around it, which means the fields of different currents will overlap when the cables are close. The overlapping of high-frequency currents that pass through the neutral-to-earth wires will result in a drop in the voltage of neutral-to-earth.

Therefore, the UPS’s neutral, hot, and ground wires should be separated away by at least 20 cm; however, it’s preferred that they be separated by 40 cm. If you can not separate the neutral and ground wires for construction reasons, you can use an armored shielded cable, which will have the same effect.

This solution has a significant advantage: it has no costs and can effectively reduce the interference of high-frequency currents. Furthermore, as a result of eliminating the interference of currents, the neutral-earth voltage will be reduced. The only downside of this solution appears at any configuration in the room.

The environment of the electromagnetic interference will correspond to any change in the room’s configuration, resulting in a drift in the neutral-to-earth voltage.

Solutions to Reduce the Voltage Between the Neutral and Earth (3 Phase)

Three-phase systems require solutions other than single-phase systems to reduce the voltage between neutral and earth. The first solution is to distribute and adjust the load of the single phase evenly in three phases; in addition, you will need to consider the power factor difference of the electric equipment.

The last step is to distribute reactive and active power evenly; the second solution that you can use is to ground the N wire in the load section iteratively. You must avoid using the same earthing pole as the PE wire. If there is no electrical connection, you will need to insulate the PE wire and the N pole.

The iteratively earthing of the N pole will ensure that the potential drift at bay is zero. The third solution is a device for power factor compensation which adjusts any unbalanced current. The device uses a microcomputer to adjust any unbalanced current in three-phase systems.

The method uses several quantities of single-phase power capacitors among phases by connecting them between the neutral wire and each phase, compensating for the power factor.

Source

Other Solutions for Three-Phase Systems

There are other solutions for reducing voltage between neutral and earth in three-phase systems; the first solution is to install a neutral wire of a large cross-sectional area under the area of low drift neutral-to-earth potential. As a result, the impedance of the conductor will be reduced, which means a lower voltage drop.

The second solution is to use neutral wire that is current-free; using current-free wire means a longer line. However, the expense will be considerable considering an analysis of cost-benefit. The third and last solution is using intelligent UPS products, also known as the new generation of UPS.

These UPSs are characterized by real-time monitoring of the current passing through the neutral wire. In addition, they match the rectifier’s current in a three-phase system in real-time to reduce the resultant neutral line current to zero. As a result, the increase in neutral-earth voltage will be diminished, caused by the voltage drop of the neutral line.

Conclusion

To summarize, the increase in the neutral-earth voltage will result in a short circuit with many harmful consequences like electrocutions, electrical burns, and fires. Therefore, any increase in the neutral-earth voltage must be handled as soon as possible to avoid dangerous effects.

You can reduce the voltage between the neutral and earth in single-phase or three-phase systems; however, the two systems require different solutions. The single-phase systems are easier to handle, and the neutral-to-earth voltage can be easily reduced. 

Meanwhile, the three-phase systems require some experience and effort to reduce the voltage between the neutral and the earth. You must be careful when dealing with electricity as it can cause severe injuries and even death.

Related Readings:

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