A grounded neutral will be at earth potential. A floating neutral will be at a voltage dependent upon the voltage imbalance between phases, and the design of the transformer.
In 1600 kva transformer we provide NGR (Neutral grounding resistance)
100meter
A current transformer is primarily used at the neutral point of a transformer for earth fault protection. A neutral current transformer will measure any ground fault current which will essentially flow from the star point of the transformer. A fault-detection device other devices is connected to the current transformer and, if the fault current exceeds a certain trigger value, the fault-detection device will give a trip command to an earth-fault relay to disconnect the supply of electricity to the transformer.
For earth fault protection on the windings of a delta connected transformer. Used in MV distribution. An earth fault current return path is provided by connecting a Neutral Earthing Compensator (NEC) between the three phases of the power system and the earth system. This is done at the source of the supply. The NEC transformer winding has a Zig-zag configuration with no secondary winding. The impedance of the winding is high when there is no fault on the system resulting in only a small magnetising current in the transformer windings. The Zig-zag winding configuration results in a low impedance when an earth fault condition occurs. By inserting resistance between the neutral of the Zig-zag transformer and earth, the earth fault currents can be limited to any desired value. The resistance value and rating has been standardised to allow an earth fault current of 300 amp for 10 seconds, although some older installations may still operate at the old standard of 600 amps.
There are situations where the secondary of a transformer is not grounded and the neutral is not connected to the neutral of the primary. This can cause a potential shock hazard so the secondary side needs to be protected.
Geez, because it is just that; A NEUTRAL EARTH, there should be equal potential on each side, therefore no current flow, and no voltage.
If you are reading a voltage it is the drop across the resistance to ground. To get rid of the voltage get the resistance lower. This can be accomplished by installing more ground rods to the grounding system. Utility companies usually like 3 ohms to ground or less.
It is done by connecting the neutral to earth at the transformer that produces the three-phase supply. If the three phase wire supply equal currents, there is no current in the neutral wire and its whole length stays at earth potential, but if there is current in the neutral it produces a small voltage on the neutral at places away from the transformer.
An earthing transformer provides a neutral in a delta connected system.
iT IS ISMILAR TO THE GROUND RESITOR CALCULATION FOR TRANSFOMER THE TYPICAL EXAMPLE WAS ANSWERED EARLIER FOR TRANSFORMER DT.19-06-2009 Neutral of transformer can be grounded solidly earthed OR with Neutral Grounded with Resistance. Typical shunt calculations fro 5 MAV 11/6.6 kv transformer neutral are as :_ Transformer rating = 5 MVA Voltage ratio = 11/6.6 KV Vector Group = Dyn11 (6.6 KV ground through Resistor) During Earth fault voltage between Neutral & Earth = 6.6/√3 = 3.81 KV Earth Fault current will be limited to = 5 x 10³ /(√3 x 6.6) = 437.38Amp. N.G.R. value in ohm = V / I = (3.81 x 10³) / 437.38 = 8.71 Ohm Value of N.G.R. is 437.38 Amp, 8.71 Ohm., 10 Sec NGR are inserted On Higher voltage to restrict earth fault current BY SRI
In 1600 kva transformer we provide NGR (Neutral grounding resistance)
In a distribution transformer's star-connected secondary, the common point of connection is called the 'star point' and is connected to earth. The star point then provides the neutral connection for the transformer secondary, providing a return path for any unbalanced currents due to an unbalanced three-phase load.This arrangement provides a four-wire distribution system, comprising three line conductors and one neutral conductor (in addition, there are various methods of providing an earth connection to consumers). The line-to-line voltage is called a line voltage (in the UK, 400 V), while a line-to-neutral voltage is called a phase voltage (in the UK, 230 V). The line voltage being 1.732 x phase voltage.
100meter
A current transformer is primarily used at the neutral point of a transformer for earth fault protection. A neutral current transformer will measure any ground fault current which will essentially flow from the star point of the transformer. A fault-detection device other devices is connected to the current transformer and, if the fault current exceeds a certain trigger value, the fault-detection device will give a trip command to an earth-fault relay to disconnect the supply of electricity to the transformer.
For earth fault protection on the windings of a delta connected transformer. Used in MV distribution. An earth fault current return path is provided by connecting a Neutral Earthing Compensator (NEC) between the three phases of the power system and the earth system. This is done at the source of the supply. The NEC transformer winding has a Zig-zag configuration with no secondary winding. The impedance of the winding is high when there is no fault on the system resulting in only a small magnetising current in the transformer windings. The Zig-zag winding configuration results in a low impedance when an earth fault condition occurs. By inserting resistance between the neutral of the Zig-zag transformer and earth, the earth fault currents can be limited to any desired value. The resistance value and rating has been standardised to allow an earth fault current of 300 amp for 10 seconds, although some older installations may still operate at the old standard of 600 amps.
There are situations where the secondary of a transformer is not grounded and the neutral is not connected to the neutral of the primary. This can cause a potential shock hazard so the secondary side needs to be protected.
In the case of a step-down transformer, the secondary winding is earthed (grounded) to provide protection against an insulation breakdown between the high voltage and low voltage windings -in other words to deliberately cause an earth fault that will initiate the operation of the high-voltage system's protection system. At the same time, it provides a zero-potential point of reference for all potentials measured on the low-voltage system, and a means by which earth-fault currents can return to the source. In the case of a three-phase transformer supplying an unbalanced load, an unearthed star-point will result in a 'floating neutral', which means that the three phase voltages will likely be unbalanced (i.e. different from each other).