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calculate

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  1. S

    How to calculate the true power|!

    I need to calculate the true power and reactive power and i no the formula for true power is V x I x cos and reactive power is apparent power-true power squared. however the figures it have been given are the load size of 50KVA at a power factor of 0.7??? any help on this would be appreciated...
  2. L

    how to calculate and avoid the Voltage drop at starting of gas compressor

    In a gas power plant There are 2 main transformers ( st1 , st2 ) taking from the grid 380 kv and step down to 13.8 kv ,and then feeding the main bus which it is divided into 2 buses ( A Feed by st1 , B Feed by st2 ) between them bus tie st1 = 380 kv/13.8 kv st2= st1 Bus A feeding gas...
  3. L

    how to calculate and avoid the Voltage drop at starting of gas compressor

    in a gas power plant There are 2 main transformers ( st1 , st2 ) taking from the grid 380 kv and step down to 13.8 kv ,and then feeding the main bus which it is divided into 2 buses ( A Feed by st1 , B Feed by st2 ) between them bus tie st1 = 380 kv/13.8 kv st2= st1 Bus A feeding gas...
  4. B

    Calculate Earth Loop Impedance - Cable >35mm2 Impedance Data

    Hi all, Where do I get phase (Z1) and earth (Z2) conductor impedances to calculate earth fault loop impedance? I have seen (R1 + R2) tables which give combinations for cable sizes up to 35 mm2. What about cables > 35 mm2? Can I use voltage drop tables (for phase conductors) from Appendix 4 in...
  5. S

    Calculate the cpc size

    How do i calculate the required size of the cpc?
  6. Sparky Ninja

    Megger Mft 1730 calculating R1&R2?

    A student of mine had his new toy delivered today (delivery first thing, thank you very much Tester Meter). We've had a play with it and I am surprised to see that it has a method of caculating R1&R2 as what appears to be normal practice. You turn the dial to Zref, make a loop impedance...
  7. N

    Who does just a Zs when carrying out a periodic on a lighting circuit

    Just answered a question on another post ,and it dawned on me , yippee the brain kicked into gear , i have read on loads of posts that people say doing an inspection just calculate the R1R2 by doing a Zs and taking away the Ze , i have never liked this method and heres a reason why ...
  8. R

    Help checking lighting circuit

    Hi Guys When checking a lighting circuit you obviously need to check at each point on the circuit, switch and light fitting. What do you do when you can't get to the cable in the light fitting?? For example, in my kitchen I have 3 spot lights on a bar. I'm not able to remove the bar...
  9. gr7

    Calculate distance between rows of panels on flat roof

    Does anyone know how to calculate the required distance between rows of modules to avoid any shading issues? I may need to mount the panels at less than 30° to avoid the need for planning permission and would rather not use mounts such as the Solion model as these waste valuable roof space...
  10. N

    Calculating 3 phase kva

    My brains switched off chaps and i can remember how to calculate 3 phase kva i know its V x I x 1.73 / 1000 so is it 230 or 400 x I x 1.73 / 1000 fee a right numpty cant belive ive forgotten it not done 3 phase calcs for a while please enlighten me to the correct figures then ill give my...
  11. P

    Is that matthew is the best model to calculate ARc fault current?

    i need a optimal model for calculating arc fault current in low voltage switchboard. where can i get a sample case of arc fault current ,so that i can calculate by different model of formula? Hope that u all can help me....please!!!!
  12. Jimmy Boy

    Can someone tell me the power consumption of a 110V Tranny when off ?

    I guess if I knew the resistance of the Primary coil I could calculate it ? but wondered if anyone had a reference guide to current consumption when a 110V tool is not in use ? ATB Steve
  13. S

    volt drop or not

    Hi all My question is this If a submain is run off the No.1 C/U to a No. 2 C/U, when we calculate the cable sizes for the C/U2 final circuits do we use the volt drop value of the sub main or do we use the 230v value ??? thanks for any help john
  14. P

    Zs testing

    Just wondering if everyone actually does a Zs test when filling in a schedule of results. In the OSG it says that you can measure it or calculate it by addition. I appreciate the different value stuff, just thinking it is a lot easier and quicker to be adding 2 figures together than taking...
  15. M

    How to calculate sizing of vacuum circuit breaker

    Hi- I am looking for some help/ advice please. I'm confused about how How to calculate sizing of vacuum circuit breaker. This project I work on it use 40m0A TP Vacuum circuit breaker to support pump 800 kW 11kV I calculate the current just 49.4 A (800*1000/1.732/11000/0.85 ) I don't know...
  16. Voltimax

    How to calculate your hourly rate

    Ok, many people come here and ask what they should be charging and how to work it out. I've been looking through my library and here is an excerpt from a book I found called 'The right way to start your own business'. I have added some extra bits in there. I hope it's helpful to all those that...
  17. G

    Verification of volt drop

    Hi, I know how to calculate volt drops on radial ccts, As a ring main is a loop and you ignore any spurs is there a voltage drop or is it considered to perfect or near perfect mains voltage regulation!. How do you,or dont you verfiy votage regulation on a ring main when certifing that you...
  18. T

    Do You.. CALCULATE or TAKE ACTUAL READINGS ??

    I dont want go on about it too much as to what the positives and negatives are of calculating (or taking actual readings) when completing either a EIC, PIR or MWC... Those of us who are testing on a very regualar basis will know the differences.. Im interested to know what method YOU choose...
  19. A

    Prospective Fault Current

    Hi Guys How do you calculate Prospective Fault Current?? Wouldi be correct in thinking it is nominal voltage divided by Zs + R1 + R2 ??? So Nominal Voltage Zs + R1 + R2 A
  20. W

    calculate zs for a 300ma rcd

    HI all. I just sat the 2391 exam last night and was asked to calculate max zs for a 300ma rcd on a 230v commercial instalation im i right in thinking using ohms law 230v devided by 300ma devided by 1000 your thoughts on this would be gratefully appreciated...

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