Transformer Neutral Earthing

Bethini,

Principally Body Earthing method & Neutral Point have different purpose for transformer grounding (which i am sure that you understand about this).

Body earthing method will eliminate any voltage that may occur due to flux leakage inside Tx nor voltage induction during operation at termination point.

Meanwhile for Neutral Point creation has a purpose to balance and "minimize" fault (both voltage & current) which may occur during operation due to unbalanced load. Usually, this Neutral point will be connected to NER for grounding purpose.

I am not sure your system configuration. From where your motors get the power supply?is it coming from your transformer also?

Thanks for your reply.

I know about earthing system.

My machine consistants of Motors (3 ph, 3 wire system), heaters and control ckt connected in 1ph. for this we need 3ph 4 wire system and using aux. TX

our machine unbalance current is approx 25A.

We will moving the machine whereever its required. some places only available 3 ph 3 wire only, in that case we use aux TX.

Regards,

hanu

As you know, the purpose of grounding is to eliminate potential voltage between earth and equipment that you can touch. The neutral is usually grounded; sometimes one of phases can be grounded, if there is no neutral...

If you have no ground, you might have no problem until one of phases of your system in some way has contact with the earth; in this case you will have voltage between earth and your equipment that will move through your body when you touch the equipment. That is the only danger. In very simple electrical systems, when you can see all parts of it, it might be easy to make sure that everything is OK, but when you have cables or wires that can touch some metal objects that are not part of your electrical system (like framing) and touch the earth, one of your phases may appear on that object, and that is the situation when voltage exists between your equipment and the earth.

It is not a problem to eliminate this situation -- just drive a rod into the earth and connect it to your neutral on your transformer; it is one of the safest way today. Good luck!

The Transformer Secondary star point is normally earthed in a 3phase system. the earth point should be proper earthing such that unbalance currents will be minimum.

if you connect temporary earthing since it is a movable equipment, i believe your earthing is not a proper one.

<...What happened if TX secondary neutral is not grounded (body earthed) and directly connected to machine?...>

One ends up with an IT earthing system, the effect of which is that fewer faults will be cleared by circuit protective devices.

Check-out the Wikipedia article on earthing systems for the latest information.

The transformer body is normally grounded separately from the neutral ground electrode (if that is what you will use). The 2 are different.

If you use the tranformer neutral for loads that require only one phase and neutral, they will operate normally even if the neutral of the transformer is not grounded. the problem is only encountered when there is a fault to ground... the protective devices will not operate since there will be no current returning to the transformer via the neutral grounded. otherwise, forget about balanced or unbalanced since the grounding of the neutral has nothing to do with these: as long as your equipment does not require grounding...like electronics, you are OK BUT NOT FAULT to ground or metal cabinets protection will will work.!

All depends on the usage and mobility strategy you are working with. Just carry some earth rods and plant them somewhere in the ground so that you can remove after....

Hi there, I am a having the same issue. recently I got the power for 8 buildings. I got complain from one tenant, he is getting electrical shock from the appliances with 2 pin plug. I tested the same and found a voltage between the body of theres appliances and the earth ( 50V to 90 volt). I got confused of the situation and I checked almost all installations in the building and found ok. The voltage between earth and neutral in all sockets, DBs and main panels is zero. Can you please advise. Thanks in advance Saleh

Please see other discussions on grounding on CR4.Some of the advice you have received here is dangerous.

Best to refer to the National Electrical Code for the proper methods.Also get a qualified electrician to perform the work, or at least to supervise the work.You are playing Russian roulete with other people's lives.

You have a right to your question or entitled to your opinion, but safety rules concerning life and property has no circumvention.

Among all the safety protection systems, earth leakage protection is the most human, life and material friendly. It is a protection systems that remains affordable from time.

Electric motors and generators are the most vulnerable to earth fault. More so earth leakage protective devices depend on the ground potential and current for efficient tripping.

The above are some of the reasons for earthing the neutral point.

Dickson.