in distribution transformer why the secondary neutral should be earthed?
969911
To say it should be earthed is not strictly correct, although it usually is for conventional protection systems especially if that neutral is made available for single phase connections.\n\nThe reason it is earthed is so that any fault that may occur causes a current to flow and operates the protection device and disconnects the supply.\n\nIf you didn't have the earth, everything would work just fine but a fault could cause a hazardous situation.\n\nSometimes the earth connection may be connected through a resistor so that a current would still flow to operate the protection but the maximum current would be limited so not to damage the transformer. This would not be done in low voltage secondaries where the neutral is used for single phase loads.\n\nA system where the neutral might not be earthed is critical systems such as military or nuclear. These systems would have some circuitry to detect a fault and give an alarm rather than trip anything.
479528
As the loads increased the line to neutral imbalance of each phase caused the neutral to ground voltage to increase.\n\nThe load of each line to line or line to neutral imbalance causes current in each phase to be imbalanced.
186909
I think the question is to the shape, size, position of the Plugs are different countries.\nInterestingly though the Live-Neutral-Ground concept is the same in all countries.\n\nIm researching on that.. Shall update my answer soon...\n\nUpdate:\nGot it!!! Check out the URL. Its the governments and the industry of each local government which had caused these different plug shapes and standards..
827050
Yupp... but unfortunately is a hardcopy on my desk. Perhaps you may straight to tell us what\n\n1. You are designing from HT to Transformer 11kV / 415V\n2. You are designinig from Transformer to LV ??\n3. What is the kVA of the transfomer?
232510
Ground is simply a common point or final destination for electricty to complete a circuit (current return). This can be at 0 volts in reference to eath ground or at some voltage higher or lower that 0v. Some TV chassis ground is +150V in reference to earth ground.
526801
Cord connected products are likely to be suspect to a higher failure rate of the grounding system, or circumvention of the grounding lead.  This can be through normal use as the appliance is moved around, the cord is flexed, and the plug is repeatedly inserted and removed from the socket through its service life.\n\nSecondly, corded products, particularly powered hand tools are more often in contact with the operator, so they present a greater a shock hazard in that respect.\n\nThird, corded products tend to see more abuse (dropping, etc.) than something that's positioned in a fixed manner.\n\nFourth, a fixed installation usually has more than one path to ground available.  While a single grounding lead is essential, the conduit also provides a grounding path.  This makes checking the ground path a little more involved as it could be achieving an earth ground through several or more paths, one of which should be the grounding wire.
829247
One would think it is a dead short.  But since the wire is coiled up around a soft iron core it forms a good sized inductor.  Since the voltage applied is a sinusoid of 60 Hz, the inductor acts as an additional impedence to current.  So you have the resistance of the thin gage wire plus the impedence of the inductor to keep things from shorting out.\n\nIncidently, when the secondary side of the transformer is conducting current, the effect of the inductor on the primary side is reduced.  So more current flows in the primary side to provide the power required by the secondary side.
1124742
Ground yourself properly !
803913
A 3-phase system requires 3 power leads A transformer or load connected delta (A to B, B to C, C to A) has no provision for a neutral connection, so there is no point in running a 4th wire. (note: a ground wire IS required by code)..a Wye, or Y connection (A to N, B to N, C to N)\nhas provision for a neutral wire.\n\nThere are 4 possible 3-phase connections,  Δ - Δ, Δ - Y, Y - Δ, and Y - Y.  Only the Y - Y connection can support a neutral, and thus 3-phase-4-wire wiring. In this system, the neutral wire carries the current resulting from unequal balancing of the phase loads.
423967
first connect all grounds then take the  neutral on the transformer to your  receptacle neutral then  take one live wire from the receptacle to the switch and from the switch to the transformer being that it is two pole you will take a wire from each pole and take each "hot leg" wire to a separate "live" connection point on the transformer, provided that it is a two phase connection
679718
The deciding factor here would be the Utility Company Service Entrance. THAT cannot be rewired by you! The other two points ( Low side of transformer and Motor Windings) can easily be configured either way by simply rewiring the 3 windings on the motor, and the 3 windings on the output of the transformer.\n\nOptimum efficiency will be DELTA-DELTA-DELTA or STAR-STAR-STAR...Either way no 'ground loops' to cause loss.
742046
For three phase AC powered loads, three separate power lines provide power to the load. The voltage waveforms on these three lines differ only in their timing, or phase relationship. A fourth wire may provide a neutral connection to the load. In the case of balanced loads, where the current in each of the three phases is equal, the current in the neutral wire will be zero. The neutral wire may therefore be eliminated, as it is not necessary for the purpose of carrying current. The vector sum of the currents drawn from the three phase lines will be zero with a balanced load. A non-zero sum of the current indicates an unbalanced load and that a current is returning to the generator, or current source, via an unintended path. This is the ground fault current.\n\nThe ground fault current for a three-phase system, without neutral, may be measured by performing a vector summation of the phase currents. This summation may be performed by a current sensing transformer with the phase currents passing through the common aperture in parallel. The magnetic field induced in the transformer core is then the vector sum of the three individual phase currents and the voltage induced in the secondary winding placed on the transformer provides a signal representing the vector sum of the currents, the ground fault current.\n\nThe electrical characteristics of ground faults in solidly grounded WYE systems allow for simple detection of ground currents by monitoring the phase and neutral currents for a simple unbalance in those currents. The principle is that the current going to the load on the normal phase and neutral conductors should return via those same conductors. Any missing current is deemed a fault to ground on the load side of the detector and, when that unbalance exceeds a set threshold, a ground fault is determined. The basic ways of measuring this unbalance for solidly grounded four-wire systems use one ground sensor surrounding the phase and neutral conductors, four individual current transformers connected in a WYE configuration, or four voltage sources connected in a delta configuration.
448145
Transformers do not store energy, that would be a battery or a capacitor.  Transformers work by wrapping wire around an iron core that is basically a circle.  For each wrap of the wire on the input side, you divide the total number of wraps into the voltage. If the input is 120 volts, and you have ten wraps, you get 12 volts per wrap.  Then, on the output side, you get an equivalent voltage per wrap.  So, that means on the example I gave, if you have five wraps on the output side you get 60 volts.  (5 x 12 volts = 60) This example would be a step down transformer, because you have a lower voltage than you started with.  If you have 20 wraps on the output side, you would get 240 volts. (20 x 12 volts = 240)  This is a step up transformer.  Note: Using Ohm's Law, you do not actually increase the total amount of power available, only change it's configuration.  Thank you, Nikola Tesla, inventor extraordinaire.
675159
Actually eclipse is wrong on the static dischargers, too.  All they do is slowly get rid of any excess charge on the plane relative to the surrounding air.\n\nThe answer to the ? is that planes AREN'T grounded electrically.  All the electrical and electronic stuff in them is grounded to the metallic structure of the plane, snd this is the return path for all current using devices.  Planes made of certain non-conductive composites use separate grounding wires and busses to do the job.
124192
It simply kills the ignition circuit. The ground or earth (i'm assuming u r referring to motor vehicles) is simply a way of using the metallic parts as a conductor in a circuit
579602
Consider a properly designed grounding system.
748193
I think the reason for the insulator layer is obvious. The conductor layer is probably to shield against emission of electromagnetic energy which can interfere with communications (such as radio and TV reception) and other electronic equipment, and may also be a safety measure to produce a high fault current to trip a breaker in the event of cable damage.