Why don’t you enquire with the VSD OEM? - do they have a support Engineer who can go to site and check config? He will likely know within an hour what the problem is and can test output
As others have suggested, it’s likely a settings issue in config but best sorted actually stood in front of...
bdn2004 - yes agree - with BSEN61439, if the control panel is small and fits within the exempted criteria, then no S/C withstand needs to be assessed / calculated / tested, provided the supply network at the POC is also less than stated exemption limits - it is not acceptable to install a 10kA...
The panel must be considered in its entirety - the fact it has different internal sections (form types) for power and control is irrelevant for certification, certainly against BSEN61439
Your extract from NEC409 references purely control panels (purely PLC + I/O etc, no power devices such as...
in the UK, Control Panels have to undergo S/C withstand analysis checks too, in accordance with BS EN 61439 (also in the EU generally)
Unsure what NEC provisions are, but from a safety point of view, you need to know this panel will safely stand the effects of a short circuit at the point of...
stevenal - yes, I read your question and answered it - it reads that you are specifying a low level trip delay on a transformer and the OEM who is quoting it, has questioned that function
the only persons who can give you that accurate and detailed response is the transformer OEM - they have...
You would only delay any functional trip application if:
> it is safe and reasonable to do so
> it is marshalled and presented via SCADA etc to someone who can evaluate the situation
> it is part of the design spec
Many conditions can momentarily slip out of tolerances or limits during normal...
Your basic analysis shows no, it isn’t from a max load perspective
Your new CNC machine will have a design loading profile, which may have diversity and therefore will not take full load, all the time
Check the transformer design spec, including the oil - all transformers allow some overloading...
Symmetrical faults have no asymmetry - they are the most onerous RMS currents but in practice are rare
Asymmetrical faults are far more common (system fault imbalance) and produce the highest peak values (during the sub transient period) - the extent of asymmetry decay is a product of system...
Symmetrical and asymmetrical are quite different - a symmetrical fault, with no dc component maintains symmetry around the x axis - an asymmetrical fault, with dc component due to X/R, has highest peak during sub transient period (first half cycle) with asymmetry decay in accordance with system...
A domestic single phase gen set randomly paralleled to a live grid would result in many scenarios, from no noticeable result to catastrophic failure of the set, dependant upon phase difference at moment of paralleling
A large 3 phase set - spectacular 💥 if not synch’d properly!
I.Eng MIMMM...
Sub transient component xd” of AC short circuit current is the initial short circuit period - the X/R ratio of system defines the dc component, hence severity of asymmetry and decay - sub transient value xd”, is used to correctly specify switchgear ratings
I.Eng MIMMM MIET MIPowerE AIOSH
87N is restricted earth fault protection REF
It is restricted to the zone protected - normally transformer LV winding and LV cable feeding the LV switchboard - the NE link and CT will be sited in the LV switchboard incomer, some distance from the transformer
I.Eng MIMMM MIET MIPowerE AIOSH
Inrush current (worst case) can be calculated and would be used in design spec for core bracing etc
There is no IEC60076 requirement to physically test it - there are many variables involved to get WC - it could be done if absolutely required, but unsure why anyone would want to
I.Eng MIMMM...
