Ground Fault make my MCB Tripped, NOT GFCI

LowQCab

Joined Nov 6, 2012
5,101
Next Question ..........
Why is "Ground-1" to "Ground-2" Resistance so small ?

Because they are both- "very good" / "Very-Efficient" / "Low-Resistance", Grounding Systems,
and there is only 1-Earth / 1-Planet, and they are both connected to Earth, or, Ground.

The better a Grounding System is, the Lower its Resistance to Current-Flow is.

Water, mixed with Minerals from the Soil / Earth / Ground / Dirt,
is an excellent Conductor of Electricity,
but,
it does have a certain, measurable, amount of Resistance,
just like a Copper Wire has Resistance.
.
.
.
 

LowQCab

Joined Nov 6, 2012
5,101
Note ...........

The Resistance of a Grounding-System is directly related to the
Combined "Surface-Area" of the Grounding-Rods measured in Sq-cm / Sq-M / M2 / Sq/In.

AND

The Water Content of the Soil / Dirt / Ground.

AND

The Mineral Content of the Soil / Dirt / Ground.
.
.
.
 

LowQCab

Joined Nov 6, 2012
5,101
MY PROBLEM ISN'T NORMAL PROBELM IS VERY COMPLEX
Question :
1. It Is Dangerous To Make Very Good Ground Rods Than Power Substation ?, 20 Meters Copper Rods 2" 5 Meters Under Soil Surface ?, I Have very enough money to do this..., I Also have small substation in my house, that feed by utility's 20.000v, My Home is for scientific... so don't assume is normal home, (100a in China is of course normally for small industry nor very very big home), also my home is former small factory
2. Can Lightning or Current Leakage In ALL Substation Load (Utility Substation) go through my ground because my ground system is far better than utility's own ground system ?, Because My Ground System Is Connected To Utility's Company Through Electrical Appliance... and Also Connected To 20kV feeder (this feeder have ground wire)..., let's say factory in near my house is have great current leakage (same 20kV system), can that current leakage goes through my ground system too ?
Note : I have two electricity Supply From Utility's One Is 100a 220v, and One Is 10a 20.000v/20kV go to my private substation (20kV/0.4kV 500kVA Transformer, Load Break Switch, Fuse Cut Out, and Also Medium and Low Voltage Switch Gear), 20kV is Wire is R-S-T and Ground/PE this is not neutral, 220v is Phase and Neutral
DO NOT GO NEAR ANY VOLTAGE OVER ~220-VOLTS !!!!!!!
NEVER-NEVER-NEVER-NEVER !!!!!!!
STAY ~3-METERS BACK !!!!!



Ground = Ground
Big Ground = Small Ground

DO NOT connect ANYTHING to a Ground that is used for High Voltage Equipment .

You have an excellent, separate, Ground System.

You should use your Separate-Grounding-System for ALL of your personal use.

The Grounding System for the "Sub-Station"
will have NO-EFFECT on your "Separate" Grounding System.

However .........
Since you are VERY close to Very-High-Voltage-Lines,
you may have more "Electrical-Noise" / "Static-Electricity" / "Voltage-Spikes".
This means that you should take "Extra-Steps" to insure that this "Electrical-Noise"
is properly "Filtered-Out" of the Electrical-Supply that you personally use.

The first thing that you should have is an "Isolation-Transformer".
this will completely separate your electrical Power from the Sub-Station.
You DO NOT want to "share" a Neutral or Ground connection from the Sub-Station.
.
.See Picture ............Chinese AC Power Problem Transformers 1 .png
.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
666
DO NOT GO NEAR ANY VOLTAGE OVER ~220-VOLTS !!!!!!!
NEVER-NEVER-NEVER-NEVER !!!!!!!
STAY ~3-METERS BACK !!!!!



Ground = Ground
Big Ground = Small Ground

DO NOT connect ANYTHING to a Ground that is used for High Voltage Equipment .

You have an excellent, separate, Ground System.

You should use your Separate-Grounding-System for ALL of your personal use.

The Grounding System for the "Sub-Station"
will have NO-EFFECT on your "Separate" Grounding System.

However .........
Since you are VERY close to Very-High-Voltage-Lines,
you may have more "Electrical-Noise" / "Static-Electricity" / "Voltage-Spikes".
This means that you should take "Extra-Steps" to insure that this "Electrical-Noise"
is properly "Filtered-Out" of the Electrical-Supply that you personally use.

The first thing that you should have is an "Isolation-Transformer".
this will completely separate your electrical Power from the Sub-Station.
You DO NOT want to "share" a Neutral or Ground connection from the Sub-Station.
.
.See Picture ............View attachment 232018
.
Your picture is definitely wrong... 20kV is 3 phase delta and doesn't came with neutral, only ground, neutral is get at 20kV/0.4kV star transformer LV side, neutral LV side is grounded and ground wire is connected to ground from utility and also connected to my ground rods..., Before Transformer there is Fuse Cut Out and Another Instruments for measuring power usage by utility company... start from transformer and bla bla bla is from customer... also after fuse cut out there is Vacuumed Circuit Breaker and another instruments inside Medium Voltage Switchgear, after there is transformer, then Low Voltage Circuit breaker with 630a ACB and 630a MCCB also ATS, Schneider Power Meter, PLC and Another Instruments...
Can Shared Ground Wire By Utility Can Make My Ground System Affected by Another Customer from Utility ?, By Contract we can refuse shared ground wire from utility or make separated independently ground rods for that (note : that ground rods also connected to lightning arrester from utility at all Medium Voltage Distribution Lines)
And 100a Isn't Supplied From these 20.000v system, that is separated system


Contract 1 : Electricity For Small Industry (100a 220v Single-Phase), For Household Loads
Contract 2 : Electricity For Small Industry (10a 20kV Three-Phase Delta), For Scientific (about 0.35 megawatt capacity... remember isn't normal home)
My Home is about 12.000m2 and also have private sub station
 

Thread Starter

meowsoft

Joined Feb 27, 2021
666
V
DO NOT GO NEAR ANY VOLTAGE OVER ~220-VOLTS !!!!!!!
NEVER-NEVER-NEVER-NEVER !!!!!!!
STAY ~3-METERS BACK !!!!!



Ground = Ground
Big Ground = Small Ground

DO NOT connect ANYTHING to a Ground that is used for High Voltage Equipment .

You have an excellent, separate, Ground System.

You should use your Separate-Grounding-System for ALL of your personal use.

The Grounding System for the "Sub-Station"
will have NO-EFFECT on your "Separate" Grounding System.

However .........
Since you are VERY close to Very-High-Voltage-Lines,
you may have more "Electrical-Noise" / "Static-Electricity" / "Voltage-Spikes".
This means that you should take "Extra-Steps" to insure that this "Electrical-Noise"
is properly "Filtered-Out" of the Electrical-Supply that you personally use.

The first thing that you should have is an "Isolation-Transformer".
this will completely separate your electrical Power from the Sub-Station.
You DO NOT want to "share" a Neutral or Ground connection from the Sub-Station.
.
.See Picture ............View attachment 232018
.
VERY WRONG PICTURE
 

Thread Starter

meowsoft

Joined Feb 27, 2021
666
I have home with 0.35 megawatt electricity (remember... not normal home... and former factory), and this is very very rare
So... I can understand if you always can't understood my question
 

Thread Starter

meowsoft

Joined Feb 27, 2021
666
Let's assume that's a factory and not a home... because very rare home like my home... also I have private and secret scientific projects that needs about 0.2 megawatt electricity...
 

Thread Starter

meowsoft

Joined Feb 27, 2021
666
Also Isn't Usual For Home To Have 20kV wire inside and also 4kV 85hp motor appliance... so let's assume that's as a factory not home...
also not all 20kV is stepped down to 230v/415v, some of 20kV is stepped down to 4kV through 20kV/4kV transformer
Also for 20kV contract, power metering is inside Medium Voltage Power Meter by utility company... there is no restrictions even if we want to use 20kV directly without transformer... so don't assume this is home...

20kV 3phase delta + shared ground -> medium voltage 20kV power metering -> my own substation (0.35 megawatt, 0.8 megawatt actual maximum capacity) 20kV/0.4kV Transformer + 20kV/4kV Transformer -> load

220v Single phase + grounded neutral -> smart meter -> home -> household load

I have two contract because one is free electricity from governments (I was worked for Chinese Governments for over 20 years at IT Research... so there is facility for me, I can use it for free without no limits practically, 35000 kwh per month)
 
Last edited:

Thread Starter

meowsoft

Joined Feb 27, 2021
666
You can mentally get shocked... if you come to my home... because it's look like big factory not a residential home... how many home in the world that use 20megawat-hours electricity every month nor operated 85hp 4kV motor inside... that's very very very very very rare
 

Thread Starter

meowsoft

Joined Feb 27, 2021
666
Distance from home building and factory building for experiments to private substation that placed 20kV step down transformer inside is about 15 meters, and also for ground rods, everything that grounded more than 1kV load must have distance over 10 meters from another building nor another ground rods (especially less than 1kV) that is regulation in China, yes... of course far from 3 meters... and I believe you can't image before I tell this that I have 20kV private substation inside my home
 

LowQCab

Joined Nov 6, 2012
5,101
1)
Can the "Shared-Ground-Wire",
supplied by the Utility Company,
Affect My Personal-Ground-System because of "Voltage-Drops" or "Voltage-Spikes" or "Electrical-Noise",
created by another Customer,
who is connected to the same "Distribution-Transformer" that supplies Power for My Smart-Meter ?

2)
By Contract we can refuse shared ground wire from utility,
and create and use our own Personal, Separate, Grounding-System.

3)
(note : that ground rods are also connected to a Lightning-Arrester-System,
installed by the Utility-Company,
at all Medium Voltage Distribution Lines)

4)
Your picture is definitely wrong...

5)
I have home with 0.35 megawatt electricity,
(remember... not normal home... and former factory),
and this is very very rare.
So... I can understand if you always can't understood my question

6)
Let's assume that my Home is not really a Home, but is an actual Factory ........
This is a very rare, and very unusual, set of circumstances .........
Also, I have private, and secret, Scientific-Projects
that need about ~0.2 Megawatts (200,000 Watts) of Power ........

7)
Also, it is unusual for any Home to have ~20kV Power-Lines inside,
and also have "Appliances" that have 4kV-85hp Motors inside ...........
so let's assume that it's a Factory, and not a normal Home .........

8)
Also, not all 20kV Supply-Lines are stepped-down to 230v/415v,
some of the 20kV is stepped-down to 4kV through a 20kV/4kV Transformer.

Also, for My 20kV Contract,
Power-Metering is handled by a large "Medium-Voltage-Power-Meter"
installed by the Utility-Company .......
There are no restrictions on how we are permitted to use the 20kV Lines,
we may even choose to use the 20kV Lines directly, without a Transformer ...........
so don't assume that this is a "normal" Home ..........

Here is a description of the general arrangement,
of the Electrical Feeds that I am concerned with ........

20kV 3-Phase-Delta + shared Ground,
going to / feeding -->
Medium-Voltage 20kV Power-Metering,
going to / feeding -->
My own Sub-Station,
( 0.35 Megawatt, 0.8 Megawatt actual Maximum-Capacity), consisting of ........
20kV/0.4kV Step-Down-Transformer, plus a 20kV/4kV Transformer,
going to / feeding -->
various Medium-Voltage-Loads,
including,
a 220v Single-Phase + Grounded-Neutral Feed,
going to / feeding -->
My personal Smart-Meter,
then going to -->
My "Home", ( Personal-Living-Space ), to supply normal Household-Loads.

I have two Contracts because one is free Electricity, paid for by the government,
( I worked for the Chinese Government for over ~20-years doing IT-Research ..........
So there is a free facility provided for me,
I can use it for free with practically no limits,
I use, (or), ( I am limited to ), 35,000 kwh per month ) .

=========================================================
Responses ..........

1)
No,
or very very small effect.

The Power-Company does not have "Ground-Wires",
they have "Neutral-Conductors" which are connected to Ground at many different points.
These Wires are properly called "Conductors" because they are actively carrying Current.
All of the multiple Ground connections are ONLY to insure that the Neutral- Conductors
STAY VERY CLOSE TO "GROUND" VOLTAGE POTENTIAL.

The "Bonding-Wires" that connect the "Neutral-Conductors" to the Ground-Rods
are not expected to have a very significant amount of Current flowing on them,
very small Current,
because there are many, many Bonding-Wires and Grounding-Rods, EVERYWHERE.

At every Junction-Box, Switch, Transformer, Meter, Electrical-Pole, ............ etc.,
there is a Bonding-Wire, and a Ground-Rod.
Because of this fact .........,
Voltage variations, above, or, below, "Ground-Voltage-Potential",
can not travel very long distances from where the disturbance was created.

BUT,
Abrupt changes, or "Noise" from other users,
can cause "Noise" or "Voltage-Spikes" on the High-Voltage-Lines,
which can affect YOUR Equipment.

But, ( I'm guessing ),
YOU are the biggest user of power in the area,
so the "smaller users" will probably be affected BY YOU,
and You will not be affected very much by the other users.

2)
That is valuable information for my improved understanding.

3)
This is a good thing.
BUT,
The Utility-Company installs this Lightening-Arrester-System to
PROTECT THEIR OWN EQUIPMENT FROM DAMAGE,
It is NOT to protect individual users equipment from damage.

4)
It is not surprising that My Picture is "wrong",
as you have a VERY UNUSUAL SITUATION.

5)
WOOOOOO that's serious power !!!!!!

6)
OK, got it.

7)
................ I used to know a guy that had a 750 Horsepower Washing Machine ............ ;) ;) ;)

8)
OK, I get the idea.

My initial effort to help was based on a "normal" Home,
My goal was to advise you on what to do to
make your Home Equipment, and Power-Supply Safe for normal Home usage,
like a Computer, or a Television-Set.

Now I see that you are talking about MUCH LARGER PROJECTS.

OK, let's start over,
and discuss what kind of problems that you are concerned about .........
.
.
.
Mad Scientist 1 .GIF
 

Thread Starter

meowsoft

Joined Feb 27, 2021
666
1)
Can the "Shared-Ground-Wire",
supplied by the Utility Company,
Affect My Personal-Ground-System because of "Voltage-Drops" or "Voltage-Spikes" or "Electrical-Noise",
created by another Customer,
who is connected to the same "Distribution-Transformer" that supplies Power for My Smart-Meter ?

2)
By Contract we can refuse shared ground wire from utility,
and create and use our own Personal, Separate, Grounding-System.

3)
(note : that ground rods are also connected to a Lightning-Arrester-System,
installed by the Utility-Company,
at all Medium Voltage Distribution Lines)

4)
Your picture is definitely wrong...

5)
I have home with 0.35 megawatt electricity,
(remember... not normal home... and former factory),
and this is very very rare.
So... I can understand if you always can't understood my question

6)
Let's assume that my Home is not really a Home, but is an actual Factory ........
This is a very rare, and very unusual, set of circumstances .........
Also, I have private, and secret, Scientific-Projects
that need about ~0.2 Megawatts (200,000 Watts) of Power ........

7)
Also, it is unusual for any Home to have ~20kV Power-Lines inside,
and also have "Appliances" that have 4kV-85hp Motors inside ...........
so let's assume that it's a Factory, and not a normal Home .........

8)
Also, not all 20kV Supply-Lines are stepped-down to 230v/415v,
some of the 20kV is stepped-down to 4kV through a 20kV/4kV Transformer.

Also, for My 20kV Contract,
Power-Metering is handled by a large "Medium-Voltage-Power-Meter"
installed by the Utility-Company .......
There are no restrictions on how we are permitted to use the 20kV Lines,
we may even choose to use the 20kV Lines directly, without a Transformer ...........
so don't assume that this is a "normal" Home ..........

Here is a description of the general arrangement,
of the Electrical Feeds that I am concerned with ........

20kV 3-Phase-Delta + shared Ground,
going to / feeding -->
Medium-Voltage 20kV Power-Metering,
going to / feeding -->
My own Sub-Station,
( 0.35 Megawatt, 0.8 Megawatt actual Maximum-Capacity), consisting of ........
20kV/0.4kV Step-Down-Transformer, plus a 20kV/4kV Transformer,
going to / feeding -->
various Medium-Voltage-Loads,
including,
a 220v Single-Phase + Grounded-Neutral Feed,
going to / feeding -->
My personal Smart-Meter,
then going to -->
My "Home", ( Personal-Living-Space ), to supply normal Household-Loads.

I have two Contracts because one is free Electricity, paid for by the government,
( I worked for the Chinese Government for over ~20-years doing IT-Research ..........
So there is a free facility provided for me,
I can use it for free with practically no limits,
I use, (or), ( I am limited to ), 35,000 kwh per month ) .

=========================================================
Responses ..........

1)
No,
or very very small effect.

The Power-Company does not have "Ground-Wires",
they have "Neutral-Conductors" which are connected to Ground at many different points.
These Wires are properly called "Conductors" because they are actively carrying Current.
All of the multiple Ground connections are ONLY to insure that the Neutral- Conductors
STAY VERY CLOSE TO "GROUND" VOLTAGE POTENTIAL.

The "Bonding-Wires" that connect the "Neutral-Conductors" to the Ground-Rods
are not expected to have a very significant amount of Current flowing on them,
very small Current,
because there are many, many Bonding-Wires and Grounding-Rods, EVERYWHERE.

At every Junction-Box, Switch, Transformer, Meter, Electrical-Pole, ............ etc.,
there is a Bonding-Wire, and a Ground-Rod.
Because of this fact .........,
Voltage variations, above, or, below, "Ground-Voltage-Potential",
can not travel very long distances from where the disturbance was created.

BUT,
Abrupt changes, or "Noise" from other users,
can cause "Noise" or "Voltage-Spikes" on the High-Voltage-Lines,
which can affect YOUR Equipment.

But, ( I'm guessing ),
YOU are the biggest user of power in the area,
so the "smaller users" will probably be affected BY YOU,
and You will not be affected very much by the other users.

2)
That is valuable information for my improved understanding.

3)
This is a good thing.
BUT,
The Utility-Company installs this Lightening-Arrester-System to
PROTECT THEIR OWN EQUIPMENT FROM DAMAGE,
It is NOT to protect individual users equipment from damage.

4)
It is not surprising that My Picture is "wrong",
as you have a VERY UNUSUAL SITUATION.

5)
WOOOOOO that's serious power !!!!!!

6)
OK, got it.

7)
................ I used to know a guy that had a 750 Horsepower Washing Machine ............ ;) ;) ;)

8)
OK, I get the idea.

My initial effort to help was based on a "normal" Home,
My goal was to advise you on what to do to
make your Home Equipment, and Power-Supply Safe for normal Home usage,
like a Computer, or a Television-Set.

Now I see that you are talking about MUCH LARGER PROJECTS.

OK, let's start over,
and discuss what kind of problems that you are concerned about .........
.
.
.
View attachment 232038
I am not biggest electricity consumer in my area... near there is also big consumer, 0.1 - 2.5 megawatt per consumer is very usual in my area... (for industry and scientific purpose, also data center, and another purpose) only about 900 meters from me there is factory with about 2.2 megawatt... let's say if they have big current leakage and connected to that shared ground is that can also take my ground system capacity ? because that is ground wire shared...

I think that's something ground wire... are you sure that is neutral wire at 20kV side ?, usually consumer get neutral point from center of star configuration at low voltage side..., and there is no information for using 20kV directly phase to neutral... I think is some one use 20kV phase - neutral that is can be very dangerous for environments..., and that ground wire is specified in contract and also optionally... but because I was want for safety installation... I plan to still use that ground wire but with separated-independently ground rods..., also what is someone in my area get ground fault at medium voltage side is that can effect my ground system ?, let's say they accidentally connected 20kV phase wire to ground... what's can happen to me ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
666
Note : In 20kV metering equipment at utility side... also they placed earth fault relay... but that's not sealed... so customer can bypass freely without penalty, customer near me is bypass that relay protection
 

LowQCab

Joined Nov 6, 2012
5,101
Distance from "Home" building and Factory-Building for Secret-Experiments,
to Private-Substation that has a 20kV Step-Down-Transformer inside,
is about 15 meters, ( or, ~45 to ~50 Feet).
And as for Ground-Rods,
every "Device-Grounding-Point",
with a Voltage higher than 1kV,
must be spaced at least 10 Meters from another building, or, another "Grounded-Device",
(especially Devices operating at less than 1kV),
that is an Electrical Regulation in China.


????? ----- yes... of course far from 3 meters...
and I believe you can't image before I tell this that I have 20kV private substation inside my home ---????

OK,
I understand the first part, ( after Editing, sorry ),
but the second part does not make very much sense,
but it does not seem to be an important piece of information.

My thoughts ...........

IT IS POSSIBLE, but very un-likely, (improbable),
to raise the Voltage-Potential,
IN A SMALL, LOCAL, AREA,
of the actual Soil / Dirt / Earth.
But this requires MASSIVE amounts of CURRENT,
and would NOT result from "Normal" Power-Usage.

Something like a DIRECT-LIGHTENING-STRIKE would be required
to make this a dangerous situation.

But the manner in which, ( the method / the way ),
ALL of the "Neutral-Conductors" are tied-together,
into a giant mesh / matrix / grid,
means that ........,
any difference in "Voltage-Potential" on ANY "Neutral-Conductor",
will be "Spread-Out" / "Dispersed" / "Smoothed-Out",
over a VERY LARGE AREA,
possibly as much as a 1- Kilometre-Square Area.

The only time when "Ground-Rod-Spacing" would be an important factor,
is when the Dirt / Earth / Soil, is very "Rocky" / "Hard", and very "Dry", ( very little water ).

But,
you have very "Favorable-Soil-Conditions" for a
VERY Efficient, VERY LOW RESISTANCE Grounding-System.
So, 'Ground-Rod-Spacing" is probably NOT going to be a problem for you.

BUT,
With Grounding Systems,
"More-is-Better", and, "Bigger-is-Better".
More numbers of Grounding-Rods, and,
More space between Grounding-Rods,
is good, generally speaking.

THE BEST GROUNDING SYSTEM ................
Unfortunately,
the very BEST Grounding System,
must be installed when the Concrete-Foundation of the Building is being made.
The Foundation of the Building is made with
Concrete, and Steel-Reinforcing-Bar, ( Re-Bar ).
Both of these Materials conduct Electricity VERY WELL,
and there are certain special methods / techniques for connecting multiple points on the
Steel "Re-Bar" with a Large-Copper-Wire,
before the Concrete is poured.

So,
you will then have multiple locations inside of the Building,
where a Large-Copper-Wire is coming out of the Concrete-Floor of the Building,
in a Pre-Planned Location,
where Electrical Equipment will be installed,
which may require a very substantial Ground connection,
such as,
a Large Transformer, or Large
"Switch-Gear" / "Switching-Station" / "Power-Distribution-Center" / "Circuit-Breaker-Panel".

This method is incredibly Effective,
because it uses THE ENTIRE BUILDING-FOUNDATION, as the "Ground-Rods".
There is absolutely no reason to add additional Grounding-Rods when using this Method.
It is "Bullet-Proof", and very close to "perfection".

Some Building Foundations are "Insulated" from the "Ground / Earth / Soil",
in that case,
"Normal" Copper-Clad Ground-Rods can be placed around the Perimeter of the Foundation,
and Connected to the "Re-Bar" inside of the Concrete-Foundation.

You should do whatever is necessary to provide a "separate" Grounding-System
for your "Home", ( "Living-Area" ), 220V-Power-Supply,
so that it will be "Electrically-Quiet",
to reduce, or eliminate, Electrical-Noise that may cause problems with
your Computer, or Television, or Radio.
The Picture with the "Isolation-Transformer" is still a very good idea,
even if your major concerns are with the operation of
other Large, High-Voltage-Equipment.

Are you having any "Problems" with your "High-Voltage-Equipment" ???

I am not an expert on High-Voltage-Equipment,
but I am familiar with the "Operating-Principles" and "may" be able to help you.
.
.
.
 

LowQCab

Joined Nov 6, 2012
5,101
1)
........... let's say if they had a big current leakage, ( Ground-Fault ),
and I am also connected to that Shared-Ground,
will that affect my Ground-System-Capacity ? ,
Because we are sharing the same Ground ............

2)
I think that's something ground wire... are you sure that is neutral wire at 20kV side ?,
usually consumer get neutral point from center of star configuration at low voltage side...,

3)
and there is no information for using 20kV directly phase to neutral...
I think is some one use 20kV phase - neutral that is can be very dangerous for environments...,

4)
and that ground wire is specified in contract and also optionally...
but because I was want for safety installation...
I plan to still use that ground wire but with separated-independently ground rods...,

5)
also what is someone in my area get ground fault
at medium voltage side is that can effect my ground system ?,
let's say they accidentally connected 20kV phase wire to ground...
what's can happen to me ?

===========================================================

My Comments .............

First,
Terminology, Word Definitions.
In the USA,
"Neutral" is a "Current-Carrying" "Conductor" that is connected to a "Grounding-System".
and is Common to all Phases of the same Voltage.

"Ground-Wire" is a "sloppy" word that is mis-used all the time, everywhere in the USA.
The Proper Term for a "Ground-Wire" is a "BOND-WIRE",
which is used for "Bonding" Equipment to a "Grounding-System".

A "Conductor" is intended to "Carry Current".
A "Bond-Wire" only carries significant Current under "GROUND-FAULT" Conditions.
A "Bond-Wire" actually may have a very small amount of Current
flowing on it under "Normal-Operating-Conditions", but it is normally extremely small.

A "Ground-Wire", or a, "Bond-Wire", IS NOT CALLED A "CONDUCTOR",
because it is NOT intended to "Carry Current",
ONLY Wires that are intended to "Carry Current" are properly called "Conductors",
so, ONLY "Phase-Wires" / "Phase-Legs", and "Neutral-Conductors" are called "Conductors".
A "Ground-Wire" is ALWAYS a "Bond-Wire", and never a "Conductor".
In the USA, a "Bond-Wire" is ALWAYS a Bare-Copper-Wire, or a, Green-Colored Insulated-Wire.

The Standard Color for a "Neutral-Conductor" is White or Gray Colored Insulation.
A "Neutral-Conductor" is also known as an "Unidentified-Conductor",
because it does not have a distinctive Color on the Insulation,
it is a "Neutral-Color".

When multiple Phases are used, the Colors usually indicate the Voltage Level.
When there is only 1-Phase, Low-Voltage, (120V), the Color is normally Black.

1)
I am confused about what you refer to as a "Shared-Ground" ..................

Normally, ( in the USA ),
"Medium-Voltages" (~600V+), and, "High-Voltages" are 3-Phases, or, 2-Phases ONLY,
( 3-Phase is DELTA-only, 2-phases are very rare ),
and the "Neutral-Conductor" is only "created" "locally",
AFTER the Phase-Legs are connected to the Primary of a "Step-Down" Transformer.
Then the "Center-Tap" of the Secondary-Winding of the Transformer,
( 3-Phase-WYE, or, a Single-Phase+Neutral ),
is "Bonded" to a "Grounding-System" with a "Bonding-Wire",
AND, the Center-Tap of the Secondary-Winding is also the
"Starting-Point" of the "Neutral-Conductor",
AND, the "purpose" of the "Neutral-Conductor" is ONLY to "Carry" and "Balance" the
small differences in Current that may exist between the "Secondary-Phase-Conductors".

In the USA, there is no "1-Phase" Power, delivered to Residential Homes,
the "Drop" to the Home is always a total of 3-Conductors ..........,
2-Phase-Conductors, and 1-Neutral-Conductor.
Then, after the Circuit-Breaker-Panel inside the Home,
there is ~240V available between the 2-Phases, or,
120V to Neutral from either Phase.
The Neutral is "Bonded" at the last Transformer, and,
where the "Service-Conductors" enter the House, at the Electric-Meter-Box.

( I got off of the Subject ),

So,
You should insist upon having a "Separate-Neutral-Conductor" to your Building.
You have your own "Sub-Station",
( High-Voltage-to Medium-Voltage, and, Medium-Voltage-to Low-Voltage Transformers ),
so there is no good reason why you should "Share" your "Neutral-Conductor"
with other Buildings that are near to your Building.

This idea of "Sharing" is a totally new-concept to Me,
so it took a considerable amount of time for Me to grasp the idea,
that You were describing as, a "Shared-Ground",
which in the USA, would be properly called a "Shared-Neutral-Conductor".

A "Shared-Neutral-Conductor" is a BAD-IDEA.
Certain types of Electrical-Loads may introduce strange Electrical-Noises into
the "Neutral-Conductor",
which could then interfere with "Sensitive" Electrical-Equipment in your Building.

YOU may actually create more problems than your neighbors are creating,
in other, nearby Buildings, that are connected to the "Shared-Neutral-Conductor".
But,
when You have a separate "Neutral-Conductor",
and, You have a Power problem,
then the problem will only be caused by YOUR Equipment,
and so,
solving the problem will be easier if You KNOW that the problem is not
being created in some other Building 100 Meters away from Your Building.

A separate, Local, Neutral-Conductor,
gives you more control over Your Power-Supply-Service.

A Transformer that will allow You to "Isolate" the Primary and Secondary Windings,
will make it possible to have complete Isolation from other Buildings,
by making it possible to have,
2-separate Neutral-Conductors that are NOT CONNECTED.

I do not know what types of Transformers are common in China,
but in the USA, most of the Transformers are "Auto-Transformer" Style,
because they are less expensive to manufacture than a
Isolated-Primary / Isolated-Secondary Style of Transformer.

A Delta / Delta Transformer is very simple to Wire with
"Isolated" Primary Windings, and "Isolated" Secondary Windings,
because there are NO Neutral-Conductor-Connections,
( only a "Bond-Wire" Connection to the Metal-Enclosure ).
Best Solution.

A WYE / WYE Transformer "may" have
permanently connected, "Common" Neutral-Conductor-Connections,
that can not be divided separately.
Possibly undesirable, but "may" work.

You DO NOT want a "Auto-Transformer" providing Power to Your Building.
It is NOT POSSIBLE to "Isolate" the Primary-Windings, from the Secondary-Windings.
BAD.


2)
Ground-Wires / Bonding-Wires do not "normally" carry Current.
Neutral-Conductors are designed to carry Current,
and are "Bonded" to Ground by a "Bond-Wire" or "Ground-Wire".

3)
~20kV is ALWAYS 3-Phase-Delta in the USA.
No Neutral.
"Bond-Wire" to Ground-Rod, is for Metal Case of Transformer,
and,
with "WYE-Secondary-Winding",
"Bonding-Wire" or "Ground-Wire" for Center-Tap / Neutral-Conductor, .


4)
Separate Neutral-Conductors = Separate Grounding Systems = Best solution.


5)
20kV Phase Wire to "Neutral-Conductor" or Ground = Blown-Fuse at other Building, and,
maybe, Voltage-Spike or Drop in YOUR Building.

Having a Separate "Neutral-Conductor" and a Separate "Grounding-System",
will only "reduce" the effects that You may experience in an event like this.
It will not "completely-stop" all of the possible effects.
 
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