fault current

fault current

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  1. J

    Power fluctuations

    I have a business owner claiming his pc monitors keep flickering and its a non consistent supply of electrix. He doewnt say he trips thr rcd but says this is dangerous as his servers are very important. He uses protection and regulation devices on his equipment. Once I test at the board and at...
  2. K

    IEC 61439-1 - Relationship between prospective fault current and diameter of copper wire

    Hi, I am currently reading through the standard IEC 61439-1 - Low-voltage swtichgear and controlgear assemblies - Part 1: General rules, and on Table 14 it is stated the "Relationship between prospective fault current and diameter of copper wire" (see picture attached). I don't understand why...
  3. UKMeterman

    100 12V car batteries in parrell fault current testing

    A youtube video on 100 car batteries in parrell and what happens when various items are short circuit current tested...
  4. Lainan01

    How does fault current loop? "Earth Fault Loop"

    Confused as to what the earth fault loop is. I'm aware it's the path that fault current takes (Line-Earth) but how many times does fault current "loop"?
  5. L

    Breaking capacity of MCBs

    Hi all, I have a question regarding the breaking capacity of circuit protective devices. So, the breaking capacity rating of devices in domestic / 230v tends to be 6ka, and for commercial / 3 phase it tends to be 10ka. Say the PFC at the origin was greater than the rating on the MCBs, and the...
  6. D

    Prospective fault current testing

    hi, new to this forum and still training. During testing for prospective fault current at the point I get a bad reading, what ever that may be????, what possible situations would be causing and why? still trying to get my head round it... thanks Adam
  7. A

    Can a BS 61008-1 RCCB be used for fault current protection

    I am aware that a BS 61008 can't be used for overload protection but is there a reason that it can't be used for fault current protection.
  8. UKMeterman

    Ukrainian prospective fault current meter

    Fault current measurement, Ukranian style
  9. newfutile

    Prospective fault current

    During a recent inspection on a 3 phase board I have some MCBs rated at 6KA And some rated at 10 KA . The ZE is about 0.04 to 0.05 depending on phase , form my calculations this works out to 9.95 KA ( I can only measure single phase pfc) On a consumer unit we allow 16KA if its backed up by a...
  10. J

    Calculating Fault Current...

    Hi all, quick question, hoping an easy one to answer. Just need to clarify this up in my own head. When calculating fault current from Zs, do I take Cmin into account? For example. Zs is 0.54 ohms So to find fault current I would calculate nominal voltage / Zs So 230 / 0.54 But, should I...
  11. P

    UK MCBs for Inverter-Supplied System

    My house is off-grid and supplied from an inverter. Max power output of the inverter is about 6kW (25A). Max fault current is 100A. The highest rated Type B MCB that can be tripped by this max fault current is 16A, so I cannot use MCBs with higher ratings than that. I cannot have a circuit with...
  12. G

    Regulation 434.5.2 - Time a conductor can withstand fault current

    Can anyone help me clarify the formula in regulation 434.5.2, the time a conductor can withstand a fault current without sustaining damage. t=k2 x S2 / I2 The regulation states I is the effective fault current. Does effective fault current mean the prospective short circuit current/...
  13. Diver233

    - Prospective fault current test 2391

    Hello all, I’m now overthinking the - Prospective fault current test for the 2391 practical, the exam boards will be a 3 phase and a single phase board. Do I test the three phase board and double the highest and use that for both DB’s or do I do one for 3 phase db1 and sep one for single phase db2
  14. C

    Fault Current Distribution

    Hello All, 1.Star connected earthed neutral Source to Star connected earthed neutral load? Say if a L-G fault occurs between the source and load, How does the fault current gets distributed? To the source side neutral or load side neutral? 2.Star- Star Transformer. Neutral earthed on both the...
  15. J

    prospective fault current

    i understand what pfc is - the maximum current that flows under fault conditions until protective device is operated.... and i know the difference between the 2 types prospective earth fault current prospective short circuit fault current My question is what (path) would prospective short...
  16. P

    Full Calculation of Perspective Fault Current - PFC

    I seem not to have access to the professional forums so I post this here: I understand ohm's law and to get a current you use Volts/Resistance (V/R); so if it's Perspective Fault Current (PFC), it's V/R or Volts/Ze; and we divided by 1000 to convert to kA. Yes? Is there a difference when...
  17. J

    Fault current, and earth electrode resistance: Numbers not making sense

    In "Advanced Electrical Installation Work" by Trevor Linsley, he says that an earth electrode rod that is 1m deep will typically have a resistance of between 10 and 200 ohms. Given that fault currents can supposedly, momentarily, be in the order of 1000's of amps, this makes me scratch my head...
  18. R

    Generator prospective fault current

    Just done a calc on a 60kva generator at 240v and 415v for max fault current got 556A at 415v and 1667A at 240v based on 15% reactance anyone care to check
  19. S

    Prospective fault current

    I have recently had test readings as follows - On a Fluke tester - loop test L/PE earth fault current 22.8 ohms but the loop test L/N was 0.14 ohms. This points to poor main earth connection. Should I report to DNO. Have done in the past and after calling to test. They only test L/N and...
  20. F

    Fault current

    Can someone explain why fault current is higher when your zs is lower trying to write down reason but struggling on what to put

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