Electrical Earth

[philiptechie]

In AC Power Transmission, what is the reason for earthing the Neutral?

For in principle at least, it would be possible to Transmit AC Power with a floating Live and Neutral.

Philiptechie

 

[cuky2000]

Grounding the neutral could help the following

-Control voltage to earth (Ground voltage reference = 0)
-Proper operation of protective devices
-Voltage stabilization.
-Path for umbalance current.
-Limits the overvoltage stress over insulation (Smaller EFF or COG)
-Reduction of short hazard in the event of accidental contact with live parts.
-Code compliances where applicable.

 

[busbar]

”Those who do not learn from history are destined to repeat it” is not meant as a trite response.

Studying others’ mistakes is an easy way to save money.

 

[philiptechie]

cuky2000 thank you for your reply.
I had'nt realised there could be several reasons for this.

The intermediate texts in electrical engineering I've looked at don't have the answers.

Do you have any suggested references on the web ?

 

[cuky2000]

Grounding is a very extensive subject that may include HV substation, GPR effect on remote location, equipment gnd, overvoltage and lightning protection, electrical noise mitigation, safety related issues, etc.

Enclose are few references that could help. I recommend searching in this forum and the Internet for additional info.

If you require further assistance, please fill free to post your questions.

Good luck.

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http://www.usace.army.mil/inet/usace-docs/eng-manuals/em1110-2-3006/c-13.pdf

http://www.ece.uidaho.edu/ee/power/EE525/lectures/L13/lect13.pdf

http://standards.ieee.org/colorbooks/sampler/Greenbook.pdf

http://www.geindustrial.com/products/applications/ngr.pdf?SMSESSION=NO

 

[busbar]

You might refer to IEEE Std C62.92.5-1992 …Application of Neutral Grounding in Electrical Utility Systems, Part V Transmission Systems and Subtransmission Systems. Table of contents at

http://standards.ieee.org/reading/ieee/std_public/description/surge/C62.92.5-1992_desc.html

 

[lyledunn]

Consider a phase to earth fault on a piece of metal equipment connected to a 3 phase floating neutral system. Should a second fault to earth occur on another phase then a phase to phase voltage will appear between the metal parts of the equipment and ground.On the other hand a grounded neutral will reduce that voltage by sqrt 3

Regards,

Lyledunn