impedance

impedance

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  1. S

    UK Amtech/Trimble - Excessive Earth Loop Impedance on SWA cables

    Hi All, I'm new to Amtech/Trimble and I've been asked to review a model. I'm looking at circuits that are SWA cables using the armour and an internal conductor as the CPC. There are various earth loop impedance errors listed where the Zs at the load end is too high, but what I can tell, Amtech...
  2. M

    G99-SGI-3 4.4 kw set export limit phase to neutral loop impedance test on site

    G99 SGI-3 4.4 kw set export limit phase to neutral loop impedance test on site 0.309 ohms and dno max being 180 m ohms or 0.018 ohms so site reading are well over the top or is this not unuall for 1950 lead cable TN-s
  3. P

    Mains cable surge impedance

    A short while back @marconi asked for the surge impedance of some 25mm SWA, so here are some related measurement results. For those who don't recognise the term, "surge impedance" is the same as "characteristic impedance" as in the 50 ohm cox cable you see advertised. It can best be explained...
  4. J

    Loop impedance measurement

    Hi, All I have a megger LTW325 and fluke 1664FC to measure loop impedance by using high current mode. But both results are quite different. megger LTW325 is given a value 0.04ohms and fluke 1664fc is given a value 0.12 ohms. Means megger can give a current at 230V/0.04=5750A but fluke is only...
  5. J

    UK Earth loop fault impedance help

    Hello I’m a student learning about industrial wiring and circuits and we’re about to start learning about how to do loop impedance calculations. I have made a drawing of a three phase installation and was wondering if anyone could give me information on how I get the Ze Zs and R1 + R2. How would...
  6. E

    Loop Impedance reading

    Hi I bought a holiday lodge last month and decided to test the circuits to see how they measured. The lodge itself is fed from a central point in the holiday village by a 16mm PVCSWA. The main earth wire terminates into a MET it looks to be a 10mm earth that is crimped onto the incoming earth, I...
  7. T

    Fault loop impedance testers

    Hi just wondering how most are testing fault loop impedance and which testing units are best
  8. E

    System Impedance

    Hi Guys found this in a Ariston 9.5kw Water heater instructions quote ''The product should be connected only to a supply with the relevant system impedance no more than 0.237 ohm. Restrictions to connection may be imposed by the supply authority on the use of equipment in the actual...
  9. H

    how would i calculate resistance using Vcc, input impedance and logic-high threshold?

  10. R

    The measured value of loop Impedance for a circuit is 2.4 Ohms

    Hello trainee forum thank you very much for letting me in here and as a consequence hopefully helping me to develop my skills and knowledge. I'm currently focusing on the 2391 and have enrolled myself on a course with no previous Inspection and testing experience or Knowledge so I do feel kind...
  11. C

    A coil of inductance 0.1 H and resistance 40 Ω is connected to a 230 V 50 Hz supply. Determine

    A coil of inductance 0.1 H and resistance 40 Ω is connected to a 230 V 50 Hz supply. Determine, showing all calculations, the impedance of the circuit. Anyone help me I don’t want the answer just a guide
  12. mak

    Is there a max Zs for lighting circuits?

    I can't find anything related to this in the regs so I probably misunderstood the question. The way I see it the max Zs for any lighting circuit depends on the circuit breaker for that circuit. Say we have a lighting circuit with 100x36W ceiling lights which gives us a load of 16A, we choose the...
  13. Mark Wright

    Max Earth Fault Loop Impedance for OverCurrent Devices Before Amendment 3 and Now???

    Maximum Earth Fault Loop Impedance for OverCurrent Device was calculated 230/(MCB Rating*5) * Rule of Thumb is that correct? And how are they worked out now after Amendment 3?
  14. H

    Working out the impedance of a circuit

    Hi Guys, Just wondering if anyone can give me a nudge in the right direction on how to work out the impedance of a circuit. The values I have to work with are that its and 230v ac inductive load circuit with a phase angle of 40 degrees and a resistance of 14 ohms. I read and re-read my text...
  15. M

    Loop Impedance tester electrical circuit

    Hi A quick one I was wondering if anyone knows how a multifunction tester performs a loop impedance test. I understand how to perform a test and what the results of a loop impedance test give you in working out your PSCC and earth fault current. I use my Fluke multifunction tester every day at...
  16. R

    Testing Loop Impedance through RCD.

    Hi, installed some circuits in a factory. The circuits were tapped off of a busbar that goes straight to the main switchgear. From this I installed a Chint RCD, which then goes to 2x Chint TP MCB and 1x Chint SP RCD. One of the TP MCB´s goes to red commando sockets and the SP MCB goes to blue...
  17. J

    RCD impedance

    Hi everyone, I appreciate this is probably a really silly question. I’ve come across the below test question and although I know how to find the answer, I don’t understand why we would need to know what the max permissible earth fault loop impedance is in relation to a 30mA RCD? I hope someone...
  18. A

    Earth Fault Loop Impedance Test for lighting circuits

    Hello guys, Do you do Earth fault loop impedance test for lighting circuits during periodic inspection ? do you measure it at the lighting point? what is the percentage of lights you test? Thanks alot in advance
  19. J

    Earth Fault Loop Impedance...

    Hi there, I’m just hoping someone could clear something up for me at all. I’m just working my way through some test questions and I’ve come across one in which isn’t making sense to me. Q. Calculate the maximum earth fault loop impedance permissible for a 30mA RCD used to protect a circuit...
  20. D

    Megger loop impedance irregularity

    Hi, I have a Megger mft1720 and the low current loop test isn’t working properly. Just wondering if anyone else has had issues? Readings are stupidly high compared to the high current test, and this can be made even worse if there’s an rcd in line......

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