Zs is the total impedance of the complete circuit and it is made up of:
- The impedance of the supply cables and transformer windings, Ze
- The resistance of our circuit line conductor, R1
- The resistance of our circuit cpc, R2
What is the difference between zze and ZS?
ZE is the earth loop reading at the intake position (fusebox etc). ZS is the earth loop reading at the furthest point on a given circuit - example being the switch drop on a lighting circuit.
What is the difference between ZS and zdb?
Sounds good to me: Zs is the whole impedance, Zdb is the impedance up to the DB where a distribution circuit is involved, Ze is the impedance external to the installation and hence measured at the point closest to the service head. Only thing to watch out for is that you don't count the impedances twice; ie Ze+Zdb.
What does Ze and ZS mean in electrical wiring?
Country: Ze is the external earth fault loop impedence. Zs is the earth fault loop impedence at the furthest point on a final circuit. They are used to ensure that automatic disconnection will be achieved in the desired time in the event of an earth fault. 20 Jan 2012. #3.
How do you measure ZS in electrical circuits?
Both usually measured together at extremity of circuit by linking L to E at consumer unit and testing across L to E on circuit. The R1 + R2 can be added to Ze to calculate Zs. If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
What is Zs and Ze?
– Zs is the earth fault loop impedance (Ω) – Ze is the measured value of external impedance (Ω), and. – (R1 + R2) is the measured value of resistance (Ω) for the line conductor and protective conductor, at the most distant point or accessory from the distribution board or consumer unit.
Is ZS higher than Ze?
So, would you fill in the forms as follows Zs 39 ohms and Zs for sockets 0.79 ohms, or would you say Zs is 39.41 ohms given that Zs strictly speaking is the sum of Ze and R1+R2?...See Also:Technical discussion forums·Wiring and the regulations·Other and general engineering discussionsArchived categoriesNov 6, 2014
How do you calculate ZS from Ze?
0:431:52Total Earth Fault Loop Impedance Zs = Ze + R1 + R2 for TN-S ... - YouTubeYouTubeStart of suggested clipEnd of suggested clipThe formula is s equals Eddie. Plus r1 plus r2 this drawing shows a TN CS earthing arrangement andMoreThe formula is s equals Eddie. Plus r1 plus r2 this drawing shows a TN CS earthing arrangement and the supplier thora T's cable. Now has a maximum external impedance Z e of 0.35 of an ohm.
Is Zs the same as earth fault loop impedance?
So in short it is the impedance of the earth fault current loop starting and ending at the point of earth fault. This impedance is abbreviated to Zs. The earth fault loop impedance can be used with the supply voltage to calculate the earth-fault current, and hence, to properly determine earth cable size.
Is Zs at DB the same as Ze?
The board fed by the sub main will have a Zs value at the board which will roughly equal Ze = R1 +R2. You measure the Zs at the incomming terminals of the sub board. This is sometimes also called Zdb. At the end of the final circuits fed from this board will be a Zs for each circuit.
What happens if Zs is too high?
If a Zs value is high, then you need to establish whether it is due to circuit conditions, supply conditions, or a fault. You can then descide the appropriate course of action. Just installing an RCD or RCBO may not be the solution in a deteriorating installation. It would appear that PME is psychic.
What is the 80% ZS rule?
The 80% rule of thumb is only intended to be applied to a test result taken from an impedance test. You have to ensure that the tested value does not exceed 80% of the tabulated value.
What is the maximum ZS permitted?
The 1.37 ohms value is the 100% max Zs value which should be recorded on the test certificate.
What is a good Zs reading?
The highest measured Zs value for each circuit should not exceed 0.8 of the relevant value in the BS 7671 tables.
What is the purpose of a Ze test?
The objective is to make sure that the circuit is disconnected fast enough to prevent overheating and possibly a fire.
How do you test Ze with Megger?
2:575:43External Earth Fault Loop Impedance Ze Test - How to Remove Parallel ...YouTubeStart of suggested clipEnd of suggested clipEarth now you'll notice with the mega testers it automatically. Starts you on a three lead lowMoreEarth now you'll notice with the mega testers it automatically. Starts you on a three lead low that's generally because rcds are in circuit. Now because i don't have an rcd. At the intake.
How do you calculate Ze?
Ze =R1 + R2. While doing testing, if your not required to take insulation resistance or an rcd time.
How do you calculate r1 r2 from Zs and Ze?
1:542:07How to calculate R1R2 and verify Zs - YouTubeYouTubeStart of suggested clipEnd of suggested clipThe measured zs by adding the calculated value for r1 plus r2 to the measured value for ze.MoreThe measured zs by adding the calculated value for r1 plus r2 to the measured value for ze.
How is ze value calculated?
Ze =R1 + R2. While doing testing, if your not required to take insulation resistance or an rcd time.
How do you calculate ZS using r1 r2?
To measure Zs do just that go to the highest point of R1+R2 on that circuit and carry out a live test. Record your result. 2. Calculate Zs by Zs=Ze+(R1+R2).
How do you measure ZS on a ring circuit?
1:066:47Earth loop impedance test on a final circuit - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd we have a figure of point eight a times. So that is the zs. For this lighting circuit is two-wayMoreAnd we have a figure of point eight a times. So that is the zs. For this lighting circuit is two-way lighting circuit so you just need to put the switches in the opposite position to chest.
How are L and E measured together?
Both usually measured together at extremity of circuit by linking L to E at consumer unit and testing across L to E on circuit.
What is ZE in a fusebox?
ZE is the earth loop reading at the intake position (fusebox etc).
How to calculate Zs?
To calculate zs is the calculation zs= ze+Zdb+ r1+r2 for the individual circuits.
What is ZDB and ZS?
Sounds good to me: Zs is the whole impedance, Zdb is the impedance up to the DB where a distribution circuit is involved, Ze is the impedance external to the installation and hence measured at the point closest to the service head. Only thing to watch out for is that you don't count the impedances twice; ie Ze+Zdb. Zdb to my knowledge is the external impedance + the resistance of the distribution circuit conductors (R1+R2). So unless you're going to measure R1+R2 on the distribution circuit (which'd require safely isolating the distribution circuit cable) then add to Ze to get Zdb I'd measure Zdb live then add R1+R2 on the final circuit to get your Zs.Hope this helps.
