S in ZS

[mst]

i know the Z stands for impedence but what does the S stand for?

is it system? does anyone know

 

[dingodeano]

i take it to mean the total e.f. impedance of the circuit in question.

Zs = Ze ( r1 + r2 ) + Zdb1
total efl ext efl dist board 1 efl e.c.t

Read the 17th edition regs book by E.C.A. its a good book.

 

[Spark123]

Isn't it just Zs = Zdb + (R1+R2)? Will Zdb not already take into account Ze i.e. Zdb = Ze + (R1+R2)?

I'm not sure what the "s" means, a lot of the symbols used do not appear to mean much i.e. Ib is design current.

 

[securespark]

Zs is defined simply as "earth fault loop impedance".

Whereas Ze is defined as that part of EFLI which is external to the installation.

 

[tim west]

I vagueley remember it from college as being s for supply but that was a long time ago

 

[GaryMo]

It's simply Zs = Ze+(R1+R2)

It generally never works out though as parallel earth paths may have an effect on measured Zs values making them lower than a calculated Zs value.

Zdb is a Zs value at the incoming connections of a submain. Back at the distribution board which feeds the submain this would be a Zs value of that circuit.
It makes more sense to call it Zdb though.

So Zs = Zdb+(R1+R2) in this case.

 

[DESL]

It generally never works out though as parallel earth paths may have an effect on measured Zs values making them lower than a calculated Zs value.

Also when measuring Zs it is carried out under AC so the inductance & capacitance of the cct will effect the result.

 

[festa]

Like Tim i was always told the S in Zs stood for supply

 

[ban-all-sheds]

i know the Z stands for impedence but what does the S stand for?

Sircuit.

 

[empip]

sumfink of impedences??

 

[baldelectrician]

I know this is not the official answer but I usually tell folk to think of the 's'' as 'socket outlet or other outlet.

 

[dingbat]

Like Tim i was always told the S in Zs stood for supply

And you were both told wrong.

S is for 'system'.

The supply loop impedance is Ze.

 

[dingodeano]

Isn't it just Zs = Zdb + (R1+R2)? Will Zdb not already take into account Ze i.e. Zdb = Ze + (R1+R2)?

I'm not sure what the "s" means, a lot of the symbols used do not appear to mean much i.e. Ib is design current.

Sorry i was over complicating my answer , i was using an example of an installation with more than one dis-board.

im with s= sum of impedances or s= system
i would suggest just plain z but this is already defined !!!

i bet the OP has long moved on!!