Which software can be used to perform a visual time simulation for flexible conductors short circuit forces? I saw a paper online using ANSYS for rigid bus not flexible ones.
Is ANSYS an easy to use software with no experience? I have not used any dedicated FEM software before
Any clues?
I got a couple of fixed 300 mA miniature RCCB and wonder if there is a way to increase its sensitivity to anything near 30 mA.
The first think is to installed a capacitor to neutral across it but is there a way to alter the internal circuit?
Thanks everyone. useful thoughts.
Are RCDs mandatory with double insulated appliances? I have seen many of these appliances comes without an earthing connection even.
Dear Mr.Che,
Thanks for your reply,
1-I am in IEC world, but would like to know the NEC world opinion in that.
2-This is probably a TN-C system in most places of 3rd world countries where just two wires are available at homes.
3-Thanks again!
In LV application, for personal safety if a 30 mA RCD/GFCI is fitted to the terminal load, would it matter if the equipment body/chassis is earthed/grounded or not for RCD operation if someone touch the faulty housing? (as long as it is not connected to the neutral).
It may be a code mandate to...
The assumption of soil temperature as the ambient for underground cables is based on infinite/too high heat capacity of soil that the cable heat generation will be absorbed totally by earth and not going to the ambient air. As this is an iterative process, the starting temperature of soil is...
I'd expect a site current injection testing to confirm the existing grid safety and then a revised study for many reasons:
1- confirm the existing design matches testing.
2- confirm the proposed design is safe with upgraded fault and clearance times, if any.
3- as the substation grid area...
Working on a transformer grounding 11/.38 kV for a mining site and wonder if the LV fault level need to be controlled to achieve compliance with low fault current for trail cables and connections inside the mining area. The addition of NER seems a simple answer but give the mining loads are...
I could find a few literature/standards are provided about railway earthing, namely the EN 50122-1 & -2.
I wonder if there are other detailed resources/textbook discussing the subject.
Please advise
I can only think of the sheath failure to ground at a bracket due to jacket punture during laying. as the cable is single point bonded and there is no current, the cable charging current will still be there and raise the sheath voltage.
Please clarify if the sheath failed near to the earthed...
If there is a fault downstream, about 15% is flowing into the transformer neutral upstream as the example shown. If the ground fault protection is set with a setting less than 15% of the rated SLG it will falsely trip and loose selectivity. So it has to have a setting higher than 15% of the...
Much appreciated Eddy, this says a lot.
I am a bit astonished to see a circulating current at the delta of XFM_YNd11 due to the SLG fault downstream XFM_Yy ( I guess it will be about 757 A instead of shown 1360 A). However this is seems reasonable for the magnetic balance of the transformer...
Thanks Eddy, I am aware of the fault current split factor between grid and earth wires.
My questions is about the fault current share between transformer neutrals upstream to the fault. e.g. 40% of the fault current returns to XFM_Gen 01 neutral and 60% to XFM_Yy neutral, if any?
Thanks EddyWirbelstorm, much appreciated.
Can you please check the neutral currents within this network, no equipment data as this is a typical network just to understand the split, assume that there is no any ground wires for TLs.
For the network hereunder, a ground fault at "F" will return to the source transformer neutral path indicated as path #"1". The equivalent zero sequence network indicate that all this current is going back to the Delta-Wye transformer between bus (A) and (B) as shown in path #"2".
It may not...
I wonder if there are much to mention about the required lug contact area for grounding conductors into steel structures and down conductors to lightning protection systems.
10 times the copper required cross-section area seems like a rule of thumb for some utilities when using steel structures...
I wonder if any came across deep rod soil investigation. Is there any guidelines, other than trial and error, on how to create a soil model (layers resistivity, thickness,...etc) from the deep rod (say up to 100 m) resistance log?
