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Disconect Main Earth. Put meter across Earth incoming (met) Connect other leads to Phase conductors do test. Then connect Earth and Neutral test leads together and connect to neutral phase conductor, connect the other lead to Line Phase conductor.
Test again. Wich ever is the highest reading in Ka record that on the test results.
Don't forget to re connect the main Met.
All these tests done with power on cons unit OFF
 
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You could also buy Guidance Notes 3 it will help you with all aspects of Testing & Inspecting
 
Disconect Main Earth. Put meter across Earth incoming (met) Connect other leads to Phase conductors do test. Then connect Earth and Neutral test leads together and connect to neutral phase conductor, connect the other lead to Line Phase conductor.
Test again. Wich ever is the highest reading in Ka record that on the test results.
Don't forget to re connect the main Met.
All these tests done with power on cons unit OFF


under what function do i set the tester?? i have a metrel 2100 easytest...thanks

You could also buy Guidance Notes 3 it will help you with all aspects of Testing & Inspecting


thank frank i think i will!!
 
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Sorry not familiar with that test set. I use Fluke 1653. But when I had Robin test kit
if I remember correctly it was the loop meter that was used for Ze and Prospective fault current. I'm sure if that's wrong a user of Robin kit will correct me
 
is there any illlustrations avaiable on the web that i could look at to help me ?
 
set your earth fault loop impedance tester to 20KA and dependent on whether you have a 2 lead or 3 lead tester you connect (3lead) green and black to neutral and red to live this is your potential short circuit current (pssc) then connect green and black to earth and red to live this is your prospective earth fault current (pefc)or (pfc) it states that you must determine the pefc and pssc at every relevant point in the installation this can be done by calculation as laney06 describes or measurement or enquiry hope that helps you.
 
Disconect Main Earth. Put meter across Earth incoming (met) Connect other leads to Phase conductors do test. Then connect Earth and Neutral test leads together and connect to neutral phase conductor, connect the other lead to Line Phase conductor.
Test again. Wich ever is the highest reading in Ka record that on the test results.
Don't forget to re connect the main Met.
All these tests done with power on cons unit OFF


Why do you need to Disconect Main Earth for the pefc test?
 
Ohms law applies to DC supply & not AC

although the ballpark figure won't be far off, it still isn't entirely accurate
 
saying V=I.R is fine, for DC theory

it is 100% correct, but i assure this is the formula for DC. when considering AC it becomes complex when you have to consider much more, ie. impedance, frequency, reactance, inductance etc.

when calculating AC power/current you are looking to give a single state value (of voltage) which is an RMS value (Route Means Squared), because as you know AC voltage is not constant it goes on positive and negative cycles up between approx +/-330V. the formula i think also includes the frequency of the supply voltage (how often the sine wave crosses 0V in a full cycle) and the peak/lowest value of voltage on the sine wave, this is then calculated to give an RMS value. I'm babbling a bit now because i can't find the best way to explain what i'm saying

i'll get onto google and see if i cant get a clearer answer
 
AC = Alternating Current,

the voltage is also alternating between approx +330V & -330V

in an AC system the voltage is never constant, which is why an RMS value is applied.

i would say it stands to reason that the maximum actual PSCC and PFC are higher than simply using ohms law to calculate from the value of 230, because you are using the RMS value, which is only about 0.7 times the actual highest value for the voltage

here's a little science lesson for you...

AC, DC and Electrical Signals
 
saying V=I.R is fine, for DC theory

it is 100% correct, but i assure this is the formula for DC. when considering AC it becomes complex when you have to consider much more, ie. impedance, frequency, reactance, inductance etc.

VIR is still the same as VIZ (z-impedance) really. Impedance is resistance that has taken into account all this frequency, reactance and inductance etc. Thats as i could see it anyway!
V = IxZ, I = V/Z, Z = V/I
 
In the instance of AC, you are taking the voltage as being a constant 230V, it is not, this is merely an RMS value, it is alternating between ~ +330V and -330V

the voltage is just as often 10V as it is 230V, or just as often -280V as it is 230V in the full sine wave cycle, and by doing AC calculations using DC theory is obviously not going to be entirely correct. it would be only correct at the exact instant where the voltage was on it's +/-230V part of it's cycle.

what my point was, in theory how can you take the PFC on an AC installation by calculation using DC theory. In reality the answer should be reached more like

Zs x 330 = Max PFC

if you dont mind me saying, Impedance has nothing to do with frequency, frequency is involved because it has an effect on the timescale of the sinusoidal waves cycle, which in turn (i think) will affect the RMS value. I also think that the reactance and inductance of the circuit could also play a part because it could cause a sort of dampening effect on the intensity of the wave, similar to rectifiying AC into DC and using capacitors to smooth the voltage, this dampening effect could perhaps also have an effect on the RMS value because of the timeframes and in turn would have an effect on the vectors when you use vector diagrams to work out the waveforms.

in honesty it's been years since college so i'm very hazy on the temrinologies and the workings of AC theory but the above is vaguely how i remember it
 
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