Typically, you could earth the star point through an earthing transformer or earting resistor to limit the fault current to FLA or less.
This is normal practice in the UK on MV systems
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Regards -
Colin J Flatters
Consulting Engineer & Project Manager
Have you looked at the equal area criteria for synchronous machine stability, using machine swing curves.
There are some useful articles on the net
_______________________________________
Regards -
Colin J Flatters
Consulting Engineer & Project Manager
In some countries, such as the UK, fault current limiters such as the ABB unit are not used since they are not regarded as 'fail safe'.
How about using an interposing transformer for the generator ?
_______________________________________
Regards -
Colin J Flatters
Consulting Engineer &...
Thanks chaps
Appreciate the help, will follow up the alternative leads, have already spoken to HiTec who have also been helpful.
_______________________________________
Regards -
Colin J Flatters
Consulting Engineer & Project Manager
If you have rotating loads, you should consider the fault contributions from these (approx same as LRA) when checking / determining the rating of the switchgear / busbars as this is the fault current seen by the busbars at the instant of the fault (at least during the sub-transient period).
IEC...
You ideally need specific test data from Terasaki if you want to look at both discrimination and cascading issues.
Not familiar with the Tembreak PD's, if thet are MCB's their fault rating is likely to be in the region of 10 - 16kA (BS EN 60947).
If you have high upstream fault levels as...
Contrary to the above, I assume that you are UK based (ie 11kV & 415 are UK system voltages), therefore the NEC is irrelevant as far as legislation is concerned, however the green book is a good source of reference (no doubt about it).
THE GEC PRAG (Protective Relay Application Guide is a...
Thanks Scotty
Had already considered the 'Harmonics / Power Factor' issues in my discussions with the client, but had completely forgotten to mention the major chesnut aka fault
current.
Completely F###s up the existing 'rotary based' design with regard to protection grading.
Have been...
Guys
As you state that the voltage is 415V, I assume you are therefore referring to a UK system, this would therefore come under the IEE Regulations (BS 7671) not the NEC, NEMA or IEEE43 (not that there is anything wrong with those standards - they just dont generally apply in the UK).
BS 7671...
Does anyone have experience and / or useful advice regarding large rotary / static UPS units.
Currently considering two 650kVA units arranged as n+1 configuration, based upon diesel / rotary units.
I have been advised that some data processing loads (servers) can operate with a leading PF...
Tend to agree with brokenhandle, I would model the fault current characteristics of each machine separately, they will have different time constants as well as reactances.
_______________________________________
Regards -
Colin J Flatters
Consulting Engineer & Project Manager
Look at the 'nominal Pi' method for modelling of transmission lines, it is relatively accurate representation.
Even if the receiving end is open circuit, you will still get capacitive charging current flowing in the line as mentioned by jgchrist.
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Regards...
Hi
The Bussmann website has some very useful data on Arcflash - suggest you take a ganders at their website
Using IEC269 / BS88 Fuses is a good way to reduce the I2t and therefore reduce Arcflash
http://www.bussmann.com/apen/pubs/spd/
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Regards -
Colin...
