Thank you JG2828, found that link too. I managed to get the manual from ABB Switzerland.
If someone else is in need for these manuals please ask, i can send them.http://files.engineering.com/getfile.aspx?folder=f655e6d5-e359-495d-b8a2-99abdfb6a475&file=CH-ES_83-92.10_E_LZ91,LZ92,LZ92-1.pdf
If you are not able to get smaller CT then you can just set the time delay of your eart fault relay to smaller value than 1 s for example 0,5s. This is not a good solution, the sensitivity of 200/1A CT you have is propably quite poor and it is very likely that you expereience unselectivity...
Hi All,
We have finally found the problem, it was quite simple (thats how all the faults seem to be after yoy have found them).
In 690V switchgear there was four pcs. 690/400V transformers for 400V small (22kW) VFD's.
Those transformers were auto-transformers eg. there is no separate windings...
I was also thinking that what if the system capacitive leakage is way more bigger than 2A, then it is possible that you can experience malfuntions?
On the other hand the DSP MKII-system will not trip before it also senses ground voltage. The phase-to-ground voltage of faulted phase has to go...
Hi!
I was once involved in project where was 6kV induction motor with direct start and 6kV capacitor bank connected to same switchgear.
There was special arrengement how to start the motor, i try to explain:
First the phase1 and phase3 of capacitor bank was closed by contactor and after 5ms...
We have a case where is some nuisance tripping of protective devices during the start of big motors (several 3,45kV 800kW induction motors). When starting big 3,45kV motors the feeder circuit breakers in 690V MCC are tripping occasionally? We have been investigating the problem and have been...
