Electrical distribution sysytem

[G.natarajan]

in 11kv /230 v delta /star connected distribution transformer neutral not connected to earh,then if we touch the one phase (ex:R phase)of secondery line, shall we get shock or not?

 

[jim hardy]

Yes.

The circuit is completed by distributed capacitance of other two phases to earth.
Current might amount to goodly fraction of an amp.
Or it might be too little to feel.

 

[G.natarajan]

Yes.

The circuit is completed by distributed capacitance of other two phases to earth.
Current might amount to goodly fraction of an amp.
Or it might be too little to feel.

Thanks.i am new to this forum.

 

[G.natarajan]

Thanks.i am new to this forum.

Dear
If the ground is neutrely charged .
And if The phase line is positively charged.
The distribution Transformer neutrel not grounded. Then we touch the line
From standing the ground what happens, will get full shock.

 

[jim hardy]

Full shock ? no.

There is capacitance from all the wires and equipment in your distribution system to earth. How much depends on the size of the system.
Currents flow through that capacitance from each phase to earth.

When everything is balanced those three currents add to zero, of course .

When you grab a phase you place yourself in parallel with one of those distributed capacitances.
So voltage across that one drops and the others rise.
How much current flows ? I'd say maximum would be 230V/X_c

There might be a little contribution from interwinding capacitance in the 11kv/230v transformer.
I've measured around 0.3 amp on a 480 system in a power plant.
That'd be a good shock and might be lethal but it wouldn't cause an explosion.
IEEE standard 241"The Green Book" recommends the neutral be earthed with a resistor approximately equal to X_c.
A good industrial reference book will have formulas to estimate distributed capacitance.