R1+R2, Ze, Zs

[Lee Gold]

Hello can someone please explain in the most simplest way possible what r1 r2 Ze and Zs mean please. All I get on Google is a book full I just need to know what they are and what do they mean. And also earth loop? Thanks

 

[Simonslimline]

r1 r2 rn are the end to end resistance values for a ring final circuits conductors.

Ze is the earth fault loop path that is external to the installation.

Zs is the total earth fault loop path from the supply transformer right the way to furthest point of a the final circuit in the installation and back to the transformer. Zs = Ze + (R1+R2). In theory this will not be the case most of the time due to parallel earth paths through equipotential bonding etc.


So Ze & Zs are both earth fault loop paths.

 

[Richard Burns]

R1 is the resistance of the line conductor from the origin of the installation (service head) to the point of testing.
R2 is the resistance of the circuit protective conductor from the origin of the installation to the point of testing.

An earth fault loop path is the "circuit" consisting of the conductors that will be carrying the fault current when a fault to earth occurs.
Start of supply from transformer, along line, round to the fault and down the circuit protective conductor (earth) back to the transformer.

Z is impedance.
Z e is external (i.e outside the installation)
Z s is system (i.e. the whole of the transformer, supply cable, service head, consumer unit, final circuit.)
R1+R2 can be considered the impednace/ resistance of the part of the earth fault loop within the installation

 

[telectrix]

as they both said. just take note of the use of upper case and lower case letters as slim explained. R1 and r1 are 2 different values.

 

[Paul.M]

Another calculation you can throw into this equation is the formula for PFC.

Measured Voltage divide by resistance = PFC.... eg:- 230V divided by 0.23 Ohms = 1KA PFC.

Formula:- Measured Voltage divided by Ze = PFC

 

[Lee Gold]

Cheers guys I'm taking notes all these formulas.... Haha

 

[Marc Lajevardi]

R1 is the resistance of the line conductor from the origin of the installation (service head) to the point of testing.
R2 is the resistance of the circuit protective conductor from the origin of the installation to the point of testing.

An earth fault loop path is the "circuit" consisting of the conductors that will be carrying the fault current when a fault to earth occurs.
Start of supply from transformer, along line, round to the fault and down the circuit protective conductor (earth) back to the transformer.

Z is impedance.
Z e is external (i.e outside the installation)
Z s is system (i.e. the whole of the transformer, supply cable, service head, consumer unit, final circuit.)
R1+R2 can be considered the impednace/ resistance of the part of the earth fault loop within the installation

could yourself or someone give an example of Ze please? So i can picture it in my head better, thanks

 

[hightower]

could yourself or someone give an example of Ze please? So i can picture it in my head better, thanks

Ze is the Earth Fault Loop Impedance external to the installation, so is done on your line supply and your earthing conductor (which has been disconnected from the MET)

 

[Marc Lajevardi]

right got it, cheers mate