Pfc testing result

[fixit4u]

Hi, anyone who can briefly explain to me how a reading at a 3-phase board on the pfc can be said to be " quite satisfactory " being show as >19.9ka

the zs at the dist board was 0.01

i phoned an experienced test engineer about my reading as i have not come across one this high before and he said it is quite ok and write it down but could not explain to me why a reading like this would be,i have only come across readings such as 3.6ka 4.1ka etc and never >19.9 and would like to know why a reading like this is ok ?

many thanks for any replies.

 

[mark80]

Well theres nothing bad about it, you have an excellent earth. I suppose the only problem you could have is the maximum breaking capacity for the protective devices as the PFC is unbelievably high. What type of fuses are in the main cut out? The place must be sitting on a substation for a reading like that

 

[not clever]

Hi, anyone who can briefly explain to me how a reading at a 3-phase board on the pfc can be said to be " quite satisfactory " being show as >19.9ka

the zs at the dist board was 0.01

i phoned an experienced test engineer about my reading as i have not come across one this high before and he said it is quite ok and write it down but could not explain to me why a reading like this would be,i have only come across readings such as 3.6ka 4.1ka etc and never >19.9 and would like to know why a reading like this is ok ?

many thanks for any replies.

Beacuse your relying on the suppliers protective device to cover the PFC?

And if anybody can give a definate answer I'll be learning something aswel, so thankyou in advance..

 

[GStueyXR]

IMO, anything above the safe breaking capacity of the incomer is not acceptable.

 

[not clever]

IMO, anything above the safe breaking capacity of the incomer is not acceptable.

Well if your on about the suppliers cutout fuse as the incommer then if it's 1361 II it'll be 33ka, granted 1361 I would be 16Ka BS88's could be even higher.

 

[sparkylad]

Hi. PFC is derived by dividing the Voltage by the resistance- so your results re not that far out.. Do remember thouigh that the PSCC on 3-phase is rouighly twice the single phase value...--Are you sure zs is 0.01, if so then you are definately relying on back up protection upstream as already posted.

 

[davewdave]

is it not only in an extreme situation that pfc would occur that high , and does this surely mean that the breakers will all trip in the quickest possible time, so it must be a good thing