High Volts in Neutral & Earth

You haven't said what the voltage is or what type of meter you're using, but a few volts isn't going to matter for any industrial power system. Assuming that you're using an analog meter, what you are observing is the degree of unbalance between phases and/or the loads, which unless your system is perfectly balanced and the loads are perfectly matched, is to be expected.

If this still bothers you then try balancing the loads by rearranging their phase position until there is no voltage difference, that will "solve" your problem for today...until something else on your supply/loading changes.

This has been brought up here many times before. To reiterate:

Voltage between earth and neutral is a function of the neutral current and the earth loop impedance.

Neutral current is a function of the imbalance between each phase's load and the difference in power factor on each phase; if the loads on each phase were equal and of the same power factor then there would be no neutral current.

If the installation is installed, tested and certified to the latest edition of BS7671, then don't worry about it.

You don't actually say what the current is, but as others have said, neutral current is due to imbalance of 3-phase loads, but I am curious why you get N-E 1.6v on no-load, especially when you say you have an N-E link.

Plasma what?

I would help if we knew:

Voltage

Neutral current

Cable size

Cable length

The point where the voltage measurements were taken. I assume the load end as there is a N→E link.

Based on 400/230V the circuit volt drop is well within the limits set by BS7671. But we don't know where the OP resides so it's anyone's guess.

As this is from an anonymous poster I doubt we'll ever get useful information.

Plasma Means LCD TV

Voltage:" 235 Volts AC

Neutral Current : No data

Cable Size: 4 Sqmm copper wire multistands

Cable Length: 105 Meters

We have taken the connection from the main panel to the DB from DB it is connected to the LCD TV's has i mention in last question

This LCD for the commerical videos purpose we are using the transmitter & Receiver to play the video due to the high volts in between of Neutral & Earth wire the receiver getting burnt. so how to reduce this volts.

So "plasma" wasn't plasma anything!!!

An LCD TV of all things. Groan....

Check the MEN link in your MDB. (you called it "main panel")

In addition to all of the other good comments I would add that Plasma generates a high level of "noise" when operating which can be measured as an AC voltage and/or a frequency signal with a meter or oscilliscope.

I would check all components and ground connections associated with the noise filter section and make sure the impedance is less than 1 ohm throughout the system ground/earth wiring.

More than likely you are just measuring the amplitude of the noise signal being generated by the plasma which is being "drained" to ground/earth.

This noise is very harmful to the controls and must be prevented from entering the controls by routing it (draining) to ground/earth.

If all machine(s) in your system are operating properly and you are not experiencing tripping issues, I would not worry about it.

If you are experiencing issues with equipment you must identify the frequency and manipulate/modify the noise filter of the plasma machine(s) so that the noise level is decreased below the trip point.

in addition to shockhiscan's good answer you can add parallel grounds to reduce ground resistance. Many plasma systems use parallel grounds to reduce this noise voltage. It is a simple fix, but not necessarily cheap. It means putting in new grounds all the way to "earth", not just adding parallel wires attached to the present earth ground.

I don't think the OP means that he actually has an MEN link installed. I think he means that the N and E are common to the loads on each phase.

OP please verify that you do in fact have an MEN link installed at your MDB.

As for the variation of V_EN with load... plasma cutters (what else could it be?) are harmonic generating monsters.

One more thing OP (aka Sudarshan the Anonymous). Why post anonymously and then sign off with your name?

Very clear case of triplen harmonic. Do a power quality audit.

Most probable reason can be Third harmonics and its multiple in Load. These turns out ultimately Zero sequence currents which flow in N ti E conductor.

If you use true RMS voltmeter tuned for 50HZ supply you will not find this voltage - and if you find this nothing to worry.

what is the voltage between earth to neutral before connecting your device ?

first you measure without load and then you connect your device and measure the same.

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